View Filing Data

$ 4,398

$ 4,141

$ 8,859

$ 8,863

1,134

921

1,792

1,604

Fuel

393

460

994

1,236

Operating and maintenance for regulatory required programs

1,114

1,111

2,175

2,472

519

439

1,033

875

186

180

383

380

3,380

3,125

6,438

6,592

1,018

1,016

2,421

2,271

Interest expense to affiliates, net

(269)

(159)

(446)

(323)

(6)

(21)

(13)

(44)

(6)

(14)

(122)

257

(29)

219

(397)

(488)

(162)

621

1,087

1,933

2,109

176

430

739

740

Pension and non-pension postretirement benefit plans:

445

657

1,194

1,369

Prior service benefit reclassified to periodic benefit cost

(6)

Actuarial loss reclassified to periodic cost

Transition obligation reclassified to periodic cost

^[1]

Pension and non-pension postretirement benefit plans valuation adjustment

(2)

(16)

Change in unrealized gain (loss) on cash-flow hedges

(409)

(220)

(26)

305

Change in unrealized gain (loss) on marketable securities

(384)

(193)

378

Average shares of common stock outstanding:

$ 61

$ 464

$ 1,205

$ 1,747

Basic

661

659

661

659

Diluted

662

661

662

661

Earnings per average common share

Basic

$ 0.67

$ 1

$ 1.81

$ 2.08

Diluted

0.67

0.99

1.8

2.07

Dividends per common share

$ 0.53

$ 1.05

Operating revenues from affiliates

Operating revenues

$ 1,628

$ 1,545

$ 3,221

$ 3,202

725

833

1,552

1,777

2,353

2,378

4,773

4,979

549

485

757

660

Fuel

350

406

740

915

Operating and maintenance from affiliate

621

605

1,285

1,453

147

164

115

223

149

118

100

1,766

1,702

3,270

3,441

587

676

1,503

1,538

(37)

(24)

(72)

(52)

(1)

(133)

215

(54)

133

(170)

191

(126)

417

867

1,377

1,618

355

434

577

Pension and non-pension postretirement benefit plans:

382

512

943

1,041

Change in unrealized gain (loss) on cash-flow hedges

(545)

(302)

657

(545)

(302)

657

(163)

210

949

1,698

Operating revenues from affiliates

Operating revenues

1,499

1,389

2,913

2,941

1,499

1,389

2,914

2,942

Purchased power from affiliate

516

368

900

812

255

347

624

786

Operating and maintenance from affiliate

240

224

360

433

Operating and maintenance for regulatory required programs

^[2]

131

124

261

246

107

136

1,243

1,180

2,367

2,527

256

209

547

415

Interest expense to affiliates, net

(130)

(72)

(211)

(152)

(4)

(3)

(7)

(126)

(20)

(207)

(72)

130

189

340

343

121

215

113

Pension and non-pension postretirement benefit plans:

116

125

230

Change in unrealized gain (loss) on cash-flow hedges

(4)

Change in unrealized gain (loss) on marketable securities

(4)

123

121

235

Operating revenues from affiliates

Operating revenues

1,268

1,201

2,721

2,712

1,269

1,204

2,724

2,718

Purchased power from affiliate

135

132

466

480

924

984

Fuel

255

321

Operating and maintenance from affiliate

127

123

286

276

Operating and maintenance for regulatory required programs

268

230

533

455

150

135

1,087

1,050

2,349

2,354

182

154

375

364

Interest expense to affiliates, net

(74)

(32)

(116)

(61)

(3)

(17)

(6)

(38)

(6)

(12)

(1)

(78)

(52)

(118)

(105)

104

102

257

259

Preferred security dividends

176

183

Net income on common stock

174

181

Pension and non-pension postretirement benefit plans:

Amortization of realized loss on settled cash flow swaps

(1)

Change in unrealized gain (loss) on marketable securities

(1)

$ 74

$ 72

$ 175

$ 183

[1]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[2]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

Consolidated Statements of Cash Flows (Unaudited) - USD ($)
$ in Millions

6 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Adjustments to reconcile net income to net cash flows provided by operating activities:

$ 1,194

$ 1,369

Impairment of long-lived assets

1,455

1,253

223

Deferred income taxes and amortization of investment tax credits

(373)

149

Net fair value change related to derivatives

(123)

Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments

(43)

278

411

(229)

286

Accounts payable, accrued expenses and other current liabilities

(239)

(469)

Option premiums paid, net

(15)

(39)

Counterparty collateral (posted) received, net

(172)

246

Pension and non-pension postretirement benefit contributions

661

(177)

(119)

(68)

(9)

(197)

2,369

3,047

Proceeds from nuclear decommissioning trust fund sales

(1,584)

(1,444)

12,528

10,150

Investment in nuclear decommissioning trust funds

(12,626)

(10,279)

Change in restricted cash

(6)

(4)

(1,658)

(1,546)

Changes in short-term debt

134

(166)

Retirement of long-term debt

485

(615)

(255)

Retirement of long-term debt of variable interest entity

(402)

Retirement of long-term debt to financing affiliates

(330)

Dividends paid on common stock

(694)

(692)

Proceeds from employee stock plans

Other financing activities

(1,553)

(934)

(842)

567

2,010

1,271

1,168

1,838

Adjustments to reconcile net income to net cash flows provided by operating activities:

943

1,041

Impairment of long-lived assets

645

526

223

Deferred income taxes and amortization of investment tax credits

(34)

100

Net fair value change related to derivatives

(123)

Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments

(43)

133

113

Receivables from and payables to affiliates, net

174

(47)

Accounts payable, accrued expenses and other current liabilities

(27)

(203)

(186)

Option premiums paid, net

(15)

(39)

Counterparty collateral (posted) received, net

(54)

245

Pension and non-pension postretirement benefit contributions

158

(68)

(65)

(33)

(34)

(21)

1,453

2,014

Proceeds from nuclear decommissioning trust fund sales

(982)

(801)

12,528

10,150

Investment in nuclear decommissioning trust funds

(12,626)

(10,279)

Change in restricted cash

(7)

(1,075)

^[1]

(926)

Retirement of long-term debt

(214)

(47)

Distribution to member

(417)

(675)

Other financing activities

(629)

(674)

(251)

414

1,099

1,135

848

1,549

Adjustments to reconcile net income to net cash flows provided by operating activities:

125

230

Deferred income taxes and amortization of investment tax credits

261

246

142

159

Receivables from and payables to affiliates, net

(156)

(81)

(31)

Accounts payable, accrued expenses and other current liabilities

(2)

(5)

(90)

Counterparty collateral (posted) received, net

(118)

Pension and non-pension postretirement benefit contributions

182

(73)

(16)

(6)

(34)

404

581

(453)

(423)

^[2]

(437)

^[1]

(421)

Changes in short-term debt

134

(15)

Retirement of long-term debt

191

(1)

(208)

Dividends paid on common stock

(150)

(120)

(17)

(152)

(50)

Adjustments to reconcile net income to net cash flows provided by operating activities:

176

183

Deferred income taxes and amortization of investment tax credits

533

455

(388)

(102)

Receivables from and payables to affiliates, net

(75)

Accounts payable, accrued expenses and other current liabilities

(21)

(154)

Pension and non-pension postretirement benefit contributions

323

(20)

(16)

(74)

(128)

555

584

Changes in Exelon intercompany money pool

(218)

(179)

(74)

Change in restricted cash

(14)

(222)

(250)

Changes in short-term debt

(95)

Retirement of long-term debt of variable interest entity

248

(402)

Retirement of long-term debt to financing affiliates

(330)

Dividends paid on common stock

(115)

(154)

Dividends paid on preferred securities

(2)

Repayment of receivable from parent

160

(429)

(173)

(96)

161

303

$ 207

$ 200

[1]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[2]	The intersegment profit associated with Generation's sale of AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 2 of the 2009 Form 10-K for additional information on AECs. For Exelon, these amounts are included in operating revenues in the Consolidated Statements of Operations.

Consolidated Balance Sheets (Unaudited) - USD ($)
$ in Millions

6 Months Ended

12 Months Ended

Jun. 30, 2010

Dec. 31, 2009

Jun. 30, 2009

Dec. 31, 2008

Restricted cash and investments

$ 1,168

$ 2,010

$ 1,838

$ 1,271

Restricted cash and cash equivalents of variable interest entity

426

1,886

1,563

451

486

418

376

Fossil fuel

174

198

Materials and supplies

585

559

459

209

5,600

5,441

28,030

27,341

Nuclear decommissioning trust funds

4,380

4,872

6,498

6,669

Investments in affiliates

708

704

Goodwill

2,625

627

649

690

859

15,543

16,398

49,173

49,180

Short-term notes payable - accounts receivable agreement

Short-term borrowings

289

155

225

Long-term debt due within one year

215

639

Long-term debt of variable interest entity due within one year

404

Long-term debt to PECO Energy Transition Trust due within one year

415

1,181

1,345

1,098

923

114

152

198

450

411

4,030

4,238

10,811

10,995

390

Deferred income taxes and unamortized investment tax credits

5,474

5,750

3,527

3,434

Pension obligations

3,527

3,625

2,278

2,180

1,018

1,017

Regulatory liabilities

3,344

3,492

1,493

1,309

20,669

20,830

$ 35,900

$ 36,453

Preferred securities

$ 87

Treasury stock, at cost (35 and 35 shares held at June 30, 2010 and December 31, 2009, respectively)

Common stock

8,960

8,923

(2,327)

(2,328)

Retained earnings

8,631

8,134

Total shareholders' equity

(2,078)

(2,089)

13,186

12,640

Total liabilities and shareholders' equity

49,173

49,180

(2,078)

(2,089)

Restricted cash and cash equivalents

848

1,099

1,549

1,135

430

495

176

112

Mark-to-market derivative assets with affiliates

418

^[1]

376

^[2]

386

^[1]

302

^[2]

Receivables from affiliates

238

297

Fossil fuel

108

102

Materials and supplies

494

470

159

102

3,260

3,360

10,221

9,809

Nuclear decommissioning trust funds

6,498

6,669

^[3]

Mark-to-market derivative assets with affiliates

612

^[1]

639

^[2]

629

^[1]

671

^[2]

Prepaid pension asset

1,018

1,027

219

185

9,018

9,237

22,499

22,406

Long-term debt due within one year

637

826

796

670

405

399

^[1]

198

^[2]

^[4]

2,022

2,262

2,777

2,967

Deferred income taxes and unamortized investment tax credits

2,676

2,707

3,406

3,316

720

659

1,018

1,017

2,069

2,228

^[1]

^[2]

480

437

10,375

10,385

$ 15,174

$ 15,614

$ 1,163

$ 1,157

Membership interest

3,465

3,464

Undistributed earnings

2,695

2,169

Total liabilities and equity

1,163

1,157

Total member's equity

7,323

6,790

^[5]

Noncontrolling interest

Total equity

7,325

6,792

22,499

22,406

Restricted cash and cash equivalents

815

676

217

318

Inventories, net

397

358

Counterparty collateral deposited

120

1,737

1,579

12,307

12,125

1,082

1,096

Investments in affiliates

^[6]

Goodwill

2,625

Receivable from affiliate

1,800

1,920

Prepaid pension asset

862

907

427

411

6,826

6,993

20,870

20,697

^[7]

Long-term debt due within one year

Short-term borrowings

289

155

213

329

274

265

282

177

Customer deposits

131

Mark-to-market derivative liabilities with affiliate

383

302

1,752

1,597

4,499

4,498

206

Deferred income taxes and unamortized investment tax credits

2,675

2,648

Mark-to-market derivative liabilities with affiliate

285

241

Regulatory liabilities

3,045

3,145

627

669

832

716

7,560

7,514

$ 14,017

$ 13,815

Common stock

$ 1,588

Other paid-in capital

4,990

Retained earnings

279

304

Total shareholders' equity

(4)

6,853

6,882

Total liabilities and shareholders' equity

20,870

20,697

(4)

Restricted cash and cash equivalents

207

303

$ 200

$ 39

Restricted cash and cash equivalents of variable interest entity

426

641

392

120

Fossil fuel

Materials and supplies

Prepaid utility taxes

112

1,635

1,006

5,421

5,297

1,403

1,834

Investments in affiliates

Receivable from affiliate

272

311

Prepaid pension asset

237

225

315

2,015

2,716

9,071

9,019

Short-term notes payable - accounts receivable agreement

225

Long-term debt of variable interest entity due within one year

404

Long-term debt to PECO Energy Transition Trust due within one year

415

147

164

132

216

189

Customer deposits

Mark-to-market derivative liabilities with affiliate

1,240

939

2,221

184

Deferred income taxes and unamortized investment tax credits

1,857

2,241

311

296

Regulatory liabilities

299

317

Mark-to-market derivative liabilities with affiliate

130

141

2,626

3,023

$ 6,271

$ 6,367

Preferred securities

$ 87

Common stock

2,318

Receivable from parent

(90)

(180)

Retained earnings

485

426

Total shareholders' equity

2,713

2,565

Total liabilities and shareholders' equity

9,071

9,019

$ 0

$ 1

[1]	Current and noncurrent assets are shown net of collateral of $586 million and $309 million, respectively, and current liabilities are shown inclusive of collateral of $3 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received and offset against mark-to-market assets and liabilities was $898 million at June 30, 2010.
[2]	Current and noncurrent assets are shown net of collateral of $502 million and $376 million, respectively, and current liabilities are shown inclusive of collateral of $69 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $947 million at December 31, 2009.
[3]	Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.
[4]	Gains and losses related to Generation's NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income.
[5]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[6]	Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.
[7]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) shares in Millions	Jun. 30, 2010	Dec. 31, 2009
Accounts Receivable [Abstract]
Gross accounts receivable pledged as collateral	$ 366,000,000
Shareholders' equity
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	2,000	2,000
Common stock, shares outstanding	661	660
Treasury Stock, Shares held	35	35
PECO ENERGY CO
Accounts Receivable [Abstract]
Gross accounts receivable pledged as collateral	$ 366,000,000

Consolidated Statement of Changes in Shareholders Equity (Unaudited) - USD ($)
shares in Thousands, $ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

$ 12,640

$ 445

$ 657

1,194

$ 1,369

(696)

(384)

(193)

378

13,186

Common Stock

$ 8,923

694,565

1,173

$ 37

$ 8,960

695,738

Treasury Stock

$ (2,328)

$ (2,327)

(2,327)

Retained Earnings

8,134

1,194

(1)

(696)

Accumulated Other Comprehensive (Loss) Income, Net

8,631

(2,089)

(2,078)

6,792

Allocation of tax benefit from member

382

512

943

1,041

Distribution to members

(417)

(545)

(302)

657

EXELON GENERATION CO LLC | Undistributed Earnings

7,325

2,169

943

Distribution to members

^[1]

(417)

EXELON GENERATION CO LLC | Membership Interest

2,695

Allocation of tax benefit from member

3,464

EXELON GENERATION CO LLC | Accumulated Other Comprehensive (Loss) Income, Net

3,465

1,157

EXELON GENERATION CO LLC | Noncontrolling Interest

1,163

2,565

176

183

Preferred security dividends

(115)

(2)

Repayment of receivable from parent

(1)

PECO ENERGY CO | Common Stock

2,713

2,318

PECO ENERGY CO | Receivable From Parent

2,318

Repayment of receivable from parent

(180)

PECO ENERGY CO | Retained Earnings

(90)

426

176

Preferred security dividends

(115)

(2)

PECO ENERGY CO | Accumulated Other Comprehensive (Loss) Income, Net

485

(1)

6,882

116

125

230

(150)

(4)

$ 7

(4)

$ 5

COMMONWEALTH EDISON CO | Common Stock

6,853

1,588

COMMONWEALTH EDISON CO | Accumulated Other Comprehensive (Loss) Income, Net

1,588

(4)

COMMONWEALTH EDISON CO | Other Paid-In Capital

(4)

4,990

COMMONWEALTH EDISON CO | Retained Deficit Unappropriated

4,990

(1,639)

Appropriation of retained earnings for future dividends

125

(187)

COMMONWEALTH EDISON CO | Retained Earnings Appropriated

(1,701)

Appropriation of retained earnings for future dividends

1,943

187

(150)

Regulatory Matters (Exelon, Generation, ComEd and PECO) [Abstract]

$ 1,980

[1]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.

Consolidated Statement of Changes in Shareholders Equity (Unaudited) (Parenthetical) - Accumulated Other Comprehensive (Loss) Income, Net $ in Millions	6 Months Ended
	Jun. 30, 2010 USD ($)
Statement [Line Items]
Other comprehensive income, income taxes	$ 7
EXELON GENERATION CO LLC
Statement [Line Items]
Other comprehensive income, income taxes	(1)
PECO ENERGY CO
Statement [Line Items]
Other comprehensive income, income taxes	0
COMMONWEALTH EDISON CO
Statement [Line Items]
Other comprehensive income, income taxes	$ (2)

Basis of Presentation (Exelon, Generation, ComEd and PECO)	6 Months Ended
	Jun. 30, 2010
Basis of Presentation (Exelon, Generation, ComEd and PECO) [Abstract]
Basis of Presentation (Exelon, Generation, ComEd and PECO)	1. Basis of Presentation (Exelon, Generation, ComEd and PECO) Exelon is a utility services holding company engaged, through its principal subsidiaries, in the generation and energy delivery businesses. The generation business consists of the electric generating facilities, the wholesale energy marketing operations and competitive retail supply operations of Generation. The energy delivery businesses include the purchase and regulated retail sale of electricity and the provision of distribution and transmission services by ComEd in northern Illinois, including the City of Chicago, and by PECO in southeastern Pennsylvania, including the City of Philadelphia, and the purchase and regulated retail sale of natural gas and the provision of distribution services by PECO in the Pennsylvania counties surrounding the City of Philadelphia. Through its business services subsidiary, BSC, Exelon provides its subsidiaries with a variety of support services at cost, including legal, human resources, financial, information technology and supply management services. The costs of BSC, including support services, are directly charged or allocated to the applicable subsidiaries using a cost-causative allocation method. Corporate governance type costs that cannot be directly assigned are allocated based on a Modified Massachusetts formula, which is a method that utilizes a combination of gross revenues, total assets, and direct labor costs for the allocation base. The results of Exelon’s corporate operations are presented as “Other” within the notes to the consolidated financial statements and include intercompany eliminations unless otherwise disclosed. Exelon owns 100% of all of its significant consolidated subsidiaries, either directly or indirectly, except for Exelon SHC, LLC, of which Generation owns 99% and the remaining 1% is indirectly owned by Exelon and is eliminated in Exelon’s consolidated financial statements, ComEd, of which Exelon owns more than 99%, and PECO, of which Exelon owns 100% of the common stock but none of PECO’s preferred securities. Exelon has reflected the third-party interests in ComEd, which totaled less than $1 million at June 30, 2010, as equity, and PECO’s preferred securities as preferred securities of subsidiary in its consolidated financial statements. Exelon’s consolidated financial statements include the accounts of entities in which Exelon has a controlling financial interest, other than certain financing trusts of ComEd and PECO, and Generation’s and PECO’s proportionate interests in jointly owned electric utility property, after the elimination of intercompany transactions. A controlling financial interest is evidenced by either a voting interest greater than 50% or the results of a model that identifies Exelon or one of its subsidiaries as the primary beneficiary of a VIE. Investments and joint ventures in which Exelon does not have a controlling financial interest and certain financing trusts of ComEd and PECO are accounted for under the equity or cost method of accounting. Each of Generation’s, ComEd’s and PECO’s consolidated financial statements includes the accounts of their subsidiaries. All intercompany transactions have been eliminated. The accompanying consolidated financial statements as of June 30, 2010 and 2009 and for the three and six months then ended are unaudited but, in the opinion of the management of each of Exelon, Generation, ComEd and PECO, include all adjustments that are considered necessary for a fair presentation of its respective financial statements in accordance with GAAP. All adjustments are of a normal, recurring nature, except as otherwise disclosed. The December 31, 2009 Consolidated Balance Sheets were taken from audited financial statements. Certain prior year amounts in Exelon’s, Generation’s and ComEd’s Consolidated Statements of Cash Flows and in ComEd’s and PECO’s Consolidated Balance Sheets have been reclassified between line items for comparative purposes. The reclassifications did not affect Exelon’s, Generation’s or ComEd’s cash flows from operating activities or ComEd’s and PECO’s financial position. These Combined Notes to Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These notes should be read in conjunction with the Notes to Consolidated Financial Statements of Exelon, Generation, ComEd and PECO included in ITEM 8 of their 2009 Annual Report on Form 10-K. *Variable Interest Entities (Exelon, Generation, ComEd and PECO)* Under the applicable authoritative guidance, VIEs are legal entities that possess any of the following characteristics: an insufficient amount of equity at risk to finance their activities, equity owners who do not have the power to direct the significant activities of the entity (or have voting rights that are disproportionate to their ownership interest), or where equity holders do not receive expected losses or returns significant to the VIE. Companies are required to consolidate a VIE if they are its primary beneficiary. Generation Generation’s wholesale operations include the physical delivery and marketing of power obtained through its generating capacity, and long-, intermediate- and short-term contracts. Generation also has contracts to purchase fuel supplies for nuclear and fossil generation. These contracts and Generation’s membership in Nuclear Electric Insurance Limited are discussed in further detail in Note 18 of the 2009 Form 10-K. Generation has evaluated these contracts and determined that either it has no variable interest in an entity or, where Generation does have a variable interest in an entity, it is not the primary beneficiary and, therefore, consolidation is not required. Several of Generation’s long-term PPAs have been determined to be operating leases that have no residual value guarantees, bargain purchase options or other provisions that would cause these operating leases to be variable interests and, therefore, not subject to this guidance. For contracts where Generation has a variable interest, Generation has considered which interest holder has the power to direct the activities that most significantly impact the economic performance of the VIE and thus is considered the primary beneficiary and is required to consolidate the entity. The primary beneficiary must also have exposure to significant losses or the right to receive significant benefits from the VIE. In general, the most significant activity of the VIEs is the operation and maintenance of the facilities, which provides the operator with the power to direct the VIEs’ activities. Facilities represent power plants, sources of uranium and fossil fuels, or plants used in the uranium conversion, enrichment and fabrication process. Generation does not have control over the operation and maintenance of the facilities considered VIEs and it does not bear operational risk of the facilities. Furthermore, Generation has no debt or equity investments in the entities, under the contracts Generation receives less than the majority of the output of the remaining expected useful life of the facilities, and Generation does not provide any other financial support through liquidity arrangements, guarantees or other commitments other than purchase commitments described in Note 12—Commitments and Contingencies. Upon consideration of these factors, Generation does not consider itself to be the primary beneficiary of these VIEs and, accordingly, has determined that consolidation is not required. Generation has aggregated its contracts with VIEs into two categories, energy commitments and fuel purchase obligations, based on the similar risk characteristics and significance to Generation. As of the balance sheet date, the carrying amount of assets and liabilities in Generation’s Consolidated Balance Sheet that relate to its involvement with VIEs are predominately related to working capital accounts and generally represent the amounts owed by Generation for the deliveries associated with the current billing cycle under the contracts. Further, Generation has not provided or guaranteed any debt or equity support, liquidity arrangements, performance guarantees or other commitments associated with these contracts, so there is no significant potential exposure to loss as a result of its involvement with the VIEs. ComEd and PECO ComEd’s retail operations include the purchase of electricity and RECs through procurement contracts of varying durations. PECO’s retail operations include the purchase of electricity, AECs and natural gas through procurement contracts of varying durations. These contracts are discussed in further detail in Notes 2 and 18 of the 2009 Form 10-K. ComEd and PECO have evaluated these contracts and determined that either they have no variable interest in a VIE or where ComEd or PECO do have a variable interest in a VIE as described below, it is not the primary beneficiary and, therefore, consolidation is not required. For contracts where ComEd or PECO has a variable interest, ComEd or PECO has considered which interest holder has the power to direct the activities that most significantly impact the economic performance of the VIE. In general, the most significant activity of the VIEs is the operation and maintenance of their production or procurement processes related to electricity, RECs, AECs or natural gas. ComEd and PECO do not have control over the operation and maintenance of the entities considered VIEs and they do not bear operational risk related to their activities. Furthermore, ComEd and PECO have no debt or equity investments in the VIEs and do not provide any other financial support through liquidity arrangements, guarantees or other commitments other than purchase commitments described in Note 12—Commitments and Contingencies. Accordingly, ComEd and PECO do not consider themselves to be the primary beneficiary of these VIEs. As of the balance sheet date, the carrying amounts of assets and liabilities in ComEd’s and PECO’s Consolidated Balance Sheet that relate to their involvement with these VIEs are predominately related to working capital accounts and generally represent the amounts owed by ComEd and PECO for the purchases associated with the current billing cycle under the contracts. The financing trust of ComEd, ComEd Financing III, and the financing trusts of PECO, PECO Trust III and PECO Trust IV, are not consolidated in Exelon’s, ComEd’s or PECO’s financial statements. These financing trusts were created to issue mandatorily redeemable trust preferred securities. ComEd and PECO have concluded that they do not have a variable interest in ComEd Financing III, PECO Trust III or PECO Trust IV as each Registrant financed its equity interest in the financing trusts through the issuance of subordinated debt and, therefore, has no equity at risk. ComEd and PECO, as the sponsors of the financing trusts, are obligated to pay the operating expenses of the trusts. PECO PETT, a financing trust, was created by PECO to purchase and own Intangible Transition Property (ITP) and to issue transition bonds to securitize $5 billion of PECO’s stranded cost recovery authorized by the PAPUC pursuant to the Competition Act. PECO made an initial capital contribution of $25 million to PETT in 1998. ITP represents the irrevocable right of PECO to collect intangible transition charges (ITC). ITC consists of the portion of CTCs that were sold by PECO to PETT and securitized through the various issuances of PETT’s transition bonds from 1999 through 2001 as authorized by the PAPUC and provides PETT with an asset sufficient to recover the aggregate principal amount of the transition bonds issued, plus amounts sufficient to provide for the credit enhancement, interest payments, servicing fees and other expenses relating to the transition bonds. PECO does not provide ongoing financial support to PETT or guarantee PETT’s performance, and the transition bondholders do not have recourse to PECO. PECO has continuing involvement in PETT in its role as the servicer of the ITC collections, for which PECO receives a fee. During the three and six months ended June 30, 2010, net pre-tax losses of $5 million and $12 million, respectively, related to PETT’s results of operations are reflected in PECO’s Consolidated Statements of Operations. PETT was consolidated in Exelon’s and PECO’s financial statements on January 1, 2010 pursuant to authoritative guidance relating to the consolidation of VIEs that became effective at that date. Under previously issued authoritative guidance, PETT was deconsolidated based on the prescribed quantitative approach, based on expected losses, of identifying the primary beneficiary. PECO has concluded that it is the primary beneficiary of PETT due to PECO’s involvement in the design of PETT and through its role as servicer of the ITC collections. Additionally, PECO has the right to dissolve PETT and receive any of its remaining assets following retirement of the transition bonds and payment of PETT’s other expenses. The consolidation of PETT did not have a significant impact on PECO’s results of operations or statement of cash flows. PETT’s assets are restricted for the sole purpose of satisfying PETT’s obligation to its transition bondholders and payment of various administrative fees as outlined in the transition bond transaction documents. As of June 30, 2010, PETT’s restricted cash balance on PECO’s Consolidated Balance Sheet was $426 million. As of June 30, 2010, PETT’s long-term debt to transition bondholders on PECO’s Consolidated Balance Sheet was $404 million, all of which is classified as long-term debt due within one year. Upon retirement of the outstanding transition bonds on September 1, 2010 and dissolution of PETT, the remaining restricted cash balance will be remitted to PECO. During the three and six months ended June 30, 2010, PECO recognized interest expense on PETT’s transition bonds of $7 million and $18 million, respectively, which is reflected in PECO’s Consolidated Statement of Operations. See Note 5 — Debt and Credit Agreements for further information regarding PETT’s debt to bondholders.

New Accounting Pronouncements (Exelon, Generation, ComEd and PECO)	6 Months Ended
	Jun. 30, 2010
New Accounting Pronouncements (Exelon, Generation, ComEd and PECO) [Abstract]
New Accounting Pronouncements (Exelon, Generation, ComEd and PECO)	2. New Accounting Pronouncements (Exelon, Generation, ComEd and PECO) The Registrants adopted the following recently issued accounting standards: *Transfers of Financial Assets* In June 2009, the FASB issued authoritative guidance amending the accounting for transfers of financial assets. This guidance was effective and applied prospectively for the Registrants beginning January 1, 2010. The impact of the adoption for Exelon and PECO and relevant disclosure is included in Note 5 — Debt and Credit Agreements. The adoption of this guidance did not impact Generation’s or ComEd’s results of operations, cash flows or financial positions. *Consolidation of Variable Interest Entities* In June 2009, the FASB issued authoritative guidance to amend the manner in which entities evaluate whether consolidation is required for VIEs. The model for determining which enterprise has a controlling financial interest and is the primary beneficiary of a VIE has changed significantly under the new guidance. Furthermore, this guidance requires that companies continually evaluate VIEs for consolidation rather than assessing based upon the occurrence of triggering events. This revised guidance also requires enhanced disclosures about how a company’s involvement with a VIE affects its financial statements and exposure to risks. This guidance became effective for the Registrants on January 1, 2010. The impact of the adoption for Exelon and PECO and relevant disclosure is included in Note 1 — Basis of Presentation. The adoption of this guidance did not impact Generation’s or ComEd’s results of operations, cash flows or financial positions. *Fair Value Measurements Disclosures* In January 2010, the FASB issued authoritative guidance intended to improve disclosures about fair value measurements. The guidance requires entities to disclose significant transfers in and out of fair value hierarchy levels and the reasons for the transfers. Additionally, the guidance clarifies that a reporting entity should provide fair value measurements for each class of assets and liabilities and disclose the inputs and valuation techniques used for fair value measurements using significant other observable inputs (Level 2) and significant unobservable inputs (Level 3). Currently, the Registrants’ mark-to-market derivative assets and liabilities and NDT fund investments are the only fair value measurements affected by this guidance. This guidance became effective for interim and annual periods beginning after December 15, 2009, except for the disclosures about purchases, sales, issuances and settlements in the Level 3 reconciliation, which will be effective for interim and annual periods beginning after December 15, 2010. As this guidance provides only disclosure requirements, the adoption of this standard did not impact the Registrants’ results of operations, cash flows or financial positions. See Note 4 — Fair Value of Financial Assets and Liabilities for additional information. The following recently issued accounting standard is not yet reflected in the combined consolidated financial statements of the Registrants: *Revenue Arrangements with Multiple Deliverables* In October 2009, the FASB issued authoritative guidance that amends existing guidance for identifying separate deliverables in a revenue-generating transaction where multiple deliverables exist, and provides guidance for allocating and recognizing revenue based on those separate deliverables. The guidance is expected to result in more multiple-deliverable arrangements being separable than under current guidance. This guidance is effective for the Registrants beginning on January 1, 2011 and is required to be applied prospectively to new or significantly modified revenue arrangements. The Registrants are currently assessing the effects this guidance may have on their consolidated financial statements.

Regulatory Matters (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Regulatory Matters (Exelon, Generation, ComEd and PECO)

3. Regulatory Matters (Exelon, Generation, ComEd and PECO)

Regulatory and Legislative Proceedings (Exelon, Generation, ComEd and PECO)

Except for the matters noted below, the disclosures set forth in Note 2 of the 2009 Form 10-K appropriately represent, in all material respects, the current status of regulatory and legislative proceedings of the Registrants. The following is an update to that discussion.

Illinois Settlement Agreement (Exelon, Generation and ComEd). Various Illinois electric utilities, their affiliates and generators of electricity in Illinois agreed to contribute approximately $1 billion over a period of four years ending in 2010 to programs to provide rate relief to Illinois electricity customers and funding for the IPA, created as a result of the Illinois Settlement Legislation. Generation recognized net costs from its contributions pursuant to the Illinois Settlement Legislation of $7 million and $9 million for the three and six months ended June 30, 2010 and $30 million and $63 million for the three and six months ended June 30, 2009, respectively, in its Consolidated Statements of Operations. ComEd’s net costs from its contributions pursuant to the Illinois Settlement Legislation were $0 and $1 million for the three and six months ended June 30, 2010, respectively, and $2 million and $3 million for the three and six months ended June 30, 2009, respectively.

As of June 30, 2010, Generation’s remaining costs to be recognized related to the rate relief commitment are $12 million, consisting of $6 million related to programs for ComEd customers and $6 million for programs for customers of other Illinois utilities. ComEd has no remaining costs to be recognized related to the rate relief commitment as of June 30, 2010.

Illinois Procurement Proceedings (Exelon and ComEd). Under the Illinois Settlement Legislation, ComEd is permitted to recover its electricity procurement costs from retail customers without mark-up. With the approval of the ICC, the IPA administers a competitive process under which ComEd procures its electricity supply based on ComEd’s anticipated supply needs.

On April 30, 2010, the ICC approved the results of ComEd’s 2010 RFP process. Approximately 25% and 6% of ComEd’s expected energy requirements for the June 2010 through May 2011 period and the June 2011 through May 2012 period, respectively, are being procured through the 2010 RFP process. The remainder of ComEd’s expected energy requirements through May 2012 will be met through additional block contracts resulting from previously completed and future RFP processes or purchased through the spot market and hedged by the financial swap contract with Generation.

The Illinois Settlement Legislation requires ComEd to purchase an increasing percentage of its electricity requirements from renewable energy resources. On May 24, 2010, the ICC approved the results of ComEd’s 2010 RFP to procure RECs for the period June 2010 through May 2011. See Note 12 of the Combined Notes to Consolidated Financial Statements for additional information on ComEd’s energy commitments.

Illinois Electric Distribution Rate Case (Exelon and ComEd). On June 30, 2010, ComEd requested ICC approval for an increase of $396 million to its net annual revenue requirement for electric distribution to allow ComEd to continue modernizing its electric delivery system and recover the costs of substantial investments made since the last rate filing in 2007. The requested increase also reflects increased costs, most notably pension and OPEB, since ComEd’s rates were last determined. The requested rate of return on common equity is 11.5%. The requested increase in electric distribution rates would increase the average residential customer’s monthly electric bill by approximately 7%. In addition, ComEd is requesting future recovery of certain amounts that were previously recorded as expense. If that request is approved, ComEd would reverse the previously expensed costs and establish regulatory assets with amortization over the period during which rate recovery is allowed. As a result, ComEd would recognize a one-time benefit of up to $39 million (pre-tax) to reverse the prior charges. The requested increase also includes $22 million for increased uncollectible accounts expense. If the rate request is approved, the threshold for determining over/under recoveries under ComEd’s uncollectible accounts tariff would be increased by $22 million. The new electric distribution rates would take effect no later than June 2011. ComEd cannot predict how much of the requested electric distribution rate increase the ICC may approve.

Illinois Legislation for Recovery of Uncollectible Accounts (Exelon and ComEd). In 2009, comprehensive legislation was enacted into law in Illinois providing public utility companies with the ability to recover from or refund to customers the difference between the utility’s annual uncollectible accounts expense and amounts collected in rates annually through a rider mechanism, starting with 2008 and prospectively. On February 2, 2010, the ICC issued an order adopting ComEd’s proposed tariffs filed in accordance with the legislation, with minor modifications. As a result of the ICC order, ComEd recorded a regulatory asset of $70 million and an offsetting reduction in operating and maintenance expense in the first quarter of 2010 for the cumulative under-collections in 2008 and 2009. Recovery of the regulatory asset associated with 2008 and 2009 activities will take place over an approximate 14-month time frame which began in April 2010. The recovery or refund of the difference in the uncollectible accounts expense applicable to the years starting with January 1, 2010, will take place over a 12-month time frame beginning in June of the following year. In addition, ComEd recorded a one-time charge of $10 million to operating and maintenance expense in the first quarter of 2010 for a contribution to the Supplemental Low-Income Energy Assistance Fund as required by the legislation. The fund is used to assist low-income residential customers.

Annual Transmission Formula Rate Update (Exelon and ComEd). ComEd’s transmission rates are established based on a FERC-approved formula. ComEd’s most recent annual formula rate update filed in May 2010 reflects actual 2009 expenses and investments plus forecasted 2010 capital additions. The update resulted in a revenue requirement of $430 million offset by a $14 million reduction related to the true-up of 2009 actual costs for a net revenue requirement of $416 million. This compares to the May 2009 updated net revenue requirement of $440 million. The decrease in the revenue requirement was primarily driven by ComEd’s 2009 cost savings measures. The 2010 net revenue requirement became effective June 1, 2010 and is recovered over the period extending through May 31, 2011. The regulatory liability associated with the true-up is being amortized as the associated revenues are refunded.

ComEd’s updated formula transmission rate currently provides for a weighted average debt and equity return on transmission rate base of 9.27%, a decrease from the 9.43% return previously authorized. As part of the FERC-approved settlement of ComEd’s 2007 transmission rate case, the rate of return on common equity is 11.5% and the common equity component of the ratio used to calculate the weighted average debt and equity return for the formula transmission rate is currently capped at 56%. This equity cap will be reduced to 55% in June 2011.

Pennsylvania Electric and Natural Gas Distribution Rate Cases (Exelon and PECO). On March 31, 2010, PECO filed separate petitions before the PAPUC for increases of $316 million and $44 million to its annual service revenue requirement for electric and natural gas delivery, respectively, to fund critical infrastructure improvement projects to meet customer demand and ensure the safe and reliable delivery of electricity and natural gas. The requested rate of return on common equity under the electric and natural gas delivery rate cases is 11.75%. The requested increase in delivery rates charged to customers for electric and natural gas as a result of the rate cases is 6.94% and 5.28%, respectively. The new electric and gas delivery rates would take effect no later than January 1, 2011. The results of the rate cases are expected to be known in the fourth quarter of 2010. PECO cannot predict how much of the requested increases the PAPUC may approve.

Pennsylvania Transition-Related Regulatory Matters (Exelon, Generation and PECO). In 2009, the PAPUC entered an Order instituting an investigation into whether PECO’s nuclear decommissioning cost adjustment clause (NDCAC), which is a mechanism that allows PECO to recover costs from customers for the decommissioning of seven former PECO nuclear units now owned by Generation, should continue after December 31, 2010. The Pennsylvania Offices of Trial Staff, Consumer Advocate, Small Business Advocate and a group of industrial customers (collectively, the parties) intervened in the proceeding. During the course of the investigation, PECO and the parties reached an agreement, as set forth in a Stipulation and Joint Memorandum filed on February 24, 2010 (Settlement) that PECO is entitled to recover decommissioning costs through the NDCAC beyond December 31, 2010. The Settlement also contained a provision in which it was agreed that PECO would not claim recovery under the NDCAC for any incremental physical decommissioning costs incurred with respect to any former PECO nuclear unit as a result of an extension of a unit’s NRC Operating License. On March 16, 2010, the ALJ issued a Recommended Decision, which concluded that PECO’s NDCAC should remain in effect beyond December 31, 2010, and recommended approval of the Settlement subject to a modification. Specifically, the ALJ stated that the provision regarding the recovery of incremental physical decommissioning costs is outside the scope of this investigation and is more appropriately considered in the NDCAC filings that are made every 5 years. Accordingly, the ALJ declined to approve this provision of the Settlement. On April 8, 2010, the parties filed exceptions to the ALJ’s proposed modification of the Settlement. On July 15, 2010, the PAPUC granted the parties’ exceptions and approved the Settlement in its entirety without the modification recommended by the ALJ. See Note 10 — Nuclear Decommissioning for additional information.

Pennsylvania Procurement Proceedings (Exelon and PECO). In 2009, the PAPUC approved PECO’s DSP Program, under which PECO will provide default electric service following the expiration of its electric generation rate caps on December 31, 2010. Under the DSP Program, PECO is permitted to recover its electricity procurement costs from retail customers without mark-up. The costs of the DSP program have been recorded as a regulatory asset as shown in the Regulatory Assets and Liabilities tables below and are recoverable through a rider mechanism over a 29-month period beginning in January 2011. On May 27, 2010, PECO entered into contracts with PAPUC approved bidders for its third competitive procurement of electric supply for default electric service customers commencing January 2011. The May 2010 procurements were for default electric service to the residential, small commercial, medium commercial and large commercial and industrial customer classes. As of June 30, 2010, including the previous competitive procurements completed in 2009, PECO has entered into contracts with terms of 17 to 29 months covering 72% of planned full requirements contracts for the residential customer class and 60% of planned full requirements contracts for the small commercial customer class, contracts with 17-month terms covering 58% of planned full requirements contracts for the medium commercial customer class and contracts with 12-month terms covering 100% of planned full requirements contracts for the large fixed-price commercial and industrial customer class in accordance with the DSP program. As of June 30, 2010, including the previous competitive procurements completed in 2009, PECO has entered into block contracts with terms of 2 to 60 months totaling 260 MW for service to the residential customer class for the years 2011 through 2015 in accordance with the DSP program. As of June 30, 2010, PECO recorded a regulatory asset to offset the mark-to-market liability recorded for derivative block contracts as shown in the Regulatory Assets and Liabilities tables below. See Note 6 — Derivative Financial Instruments for additional information on the mark-to-market liability. PECO will conduct six additional competitive procurements over the remainder of the term of the DSP Program, which expires May 31, 2013.

As part of the 2009 settlement of the DSP Program, PECO filed a Revised Electric Purchase of Receivables (POR) program that required PECO to purchase the customer accounts receivable of electric generation suppliers (EGS) that participate in the electric customer choice program and have elected consolidated billing under the 1998 Restructuring Settlement. The Revised Electric POR program was filed on November 20, 2009, and provided for full recovery of PECO’s system implementation costs for program administration through a temporary discount on purchased receivables. On June 16, 2010, the PAPUC approved PECO’s settlement of the electric POR program. The approved settlement states that PECO can terminate electric service to customers beginning January 1, 2011, based on unpaid charges for EGS service, and uncollectible account expense will be recovered from customers through distribution rates.

Smart Meter and Smart Grid Investments (Exelon and PECO). On November 25, 2009, PECO filed a joint petition with the PAPUC for partial settlement of its $550 million Smart Meter Procurement and Installation Plan to install more than 1.6 million smart meters and deploy advanced communication networks over a 15-year period. On April 22, 2010, the PAPUC approved PECO’s Smart Meter Procurement and Installation Plan that provides for recovery of program expenses, which includes accelerated depreciation incurred on existing meters due to early deployment, over the period January 1, 2011 through December 31, 2020. PECO plans to file for PAPUC approval of an initial dynamic pricing and customer acceptance program in September 2010 and for approval of a universal meter deployment plan for its remaining customers in 2012. As of June 30, 2010, PECO recorded regulatory assets related to recoverable program expenses including smart meter accelerated depreciation as shown in the Regulatory Assets and Liabilities table below.

On April 12, 2010, PECO entered into a Financial Assistance Agreement with the DOE for SGIG funds under the ARRA. Under the SGIG, PECO has been awarded $200 million, the maximum grant allowable under the program, for its SGIG project — Smart Future Greater Philadelphia. As a result of the SGIG funding, PECO will deploy 600,000 smart meters within three years, accelerate universal deployment of more than 1.6 million smart meters from 15 years to 10 years and increase Smart Grid investments to approximately $100 million over the next three years. The $200 million SGIG funds will be reimbursed ratably based on projected spending of more than $400 million, which includes approximately $7 million related to demonstration projects by two sub-recipients. The SGIG is non-taxable based on recent IRS guidance. The DOE has a conditional ownership interest in federally-funded project property and equipment, which is subordinate to PECO’s existing mortgage. In total, over the next 10 years, PECO is planning to spend up to a total of $650 million on its smart grid and smart meter infrastructure. The $200 million SGIG from the DOE will be used to significantly reduce the impact of those investments on PECO ratepayers.

Energy Efficiency Program (Exelon and PECO). Pursuant to Act 129’s EE&C reduction targets, PECO filed its EE&C plan with the PAPUC and received partial approval in 2009. On February 11, 2010, the PAPUC approved PECO’s revisions to the EE&C plan. The approved plan totals more than $330 million, which is recoverable from ratepayers. As of June 30, 2010, PECO recorded a regulatory liability for revenue billed, net of expenses incurred for the EE&C plan as shown in the Regulatory Assets and Liabilities tables below. During the three and six months ended June 30, 2010, PECO recorded recovered operating expenses and equal and offsetting operating revenues related to the energy efficiency program as shown in the Operating and Maintenance for Regulatory Required Programs table below.

Alternative Energy Portfolio Standards (Exelon and PECO). PECO will be required to comply with the AEPS Act following the end of the electric generation rate cap transition period. PECO has entered into five-year agreements with accepted bidders, including Generation, to purchase a total of 452,000 AECs annually, in order to prepare for 2011, PECO’s first year of required compliance. In 2009, the PAPUC approved a settlement of PECO’s petition for early procurement and banking of up to 8,000 solar Tier 1 AECs annually for 10 years. On March 3, 2010, PECO announced that it had entered into 10-year agreements to purchase 8,000 solar Tier 1 AECs annually.

Regulatory Assets and Liabilities (Exelon, ComEd and PECO)

Exelon, ComEd and PECO prepare their consolidated financial statements in accordance with the authoritative guidance for accounting for certain types of regulation. Under this guidance, regulatory assets represent incurred costs that have been deferred because of their probable future recovery from customers through regulated rates. Regulatory liabilities represent the excess recovery of costs or accrued credits that have been deferred because it is probable such amounts will be returned to customers through future regulated rates or represent billings in advance of expenditures for approved regulatory programs.

The following tables provide information about the regulatory assets and liabilities of Exelon, ComEd and PECO as of June 30, 2010 and December 31, 2009. For additional information on the specific regulatory assets and liabilities, refer to Note 19 of the 2009 Form 10-K.


June 30, 2010	Exelon		ComEd		PECO

Regulatory assets
Competitive transition charge	$	438	$	—	$	438
Pension and other postretirement benefits		2,540		—		16
Deferred income taxes		851		21		830
Smart meter program expenses		3		—		3
Smart meter accelerated depreciation		3		—		3
Debt costs		131		114		17
Severance		84		84		—
Asset retirement obligations		66		50		16
MGP remediation costs		136		97		39
RTO start-up costs		11		11		—
Under-recovered uncollectible accounts		49		49		—
Financial swap with Generation — noncurrent		—		627		—
DSP Program electric procurement contracts - noncurrent		2		—		4
DSP Program costs		6		—		6
Other		60		29		31


Noncurrent regulatory assets		4,380		1,082		1,403
Financial swap with Generation — current		—		383		—
Under-recovered energy and transmission costs current asset		14		14		—
DSP Program electric procurement contracts — current		2		—		5


Total regulatory assets	$	4,396	$	1,479	$	1,408


Regulatory liabilities
Nuclear decommissioning (a)	$	2,069	$	1,797	$	272
Removal costs		1,229		1,229		—
Refund of PURTA taxes		4		—		4
Energy efficiency and demand response programs		41		19		22
Other		1		—		1


Noncurrent regulatory liabilities		3,344		3,045		299
Over-recovered energy and transmission costs current liability		51		13		38


Total regulatory liabilities	$	3,395	$	3,058	$	337


December 31, 2009	Exelon		ComEd		PECO
Regulatory assets
Competitive transition charge	$	883	$	—	$	883
Pension and other postretirement benefits		2,634		—		19
Deferred income taxes		842		20		822
Debt costs		144		125		19
Severance		95		95		—
Asset retirement obligations		65		49		16
MGP remediation costs		143		103		40
RTO start-up costs		12		12		—
Financial swap with Generation—noncurrent		—		669		—
DSP Program electric procurement contracts		2		—		4
DSP Program costs		5		—		5
Other		47		23		26


Noncurrent regulatory assets		4,872		1,096		1,834
Financial swap with Generation—current		—		302		—
Under-recovered energy and transmission costs current asset		56		56		—


Total regulatory assets	$	4,928	$	1,454	$	1,834


Regulatory liabilities
Nuclear decommissioning (a)	$	2,229	$	1,918	$	311
Removal costs		1,212		1,212		—
Refund of PURTA taxes		4		—		4
Deferred taxes		30		—		—
Energy efficiency and demand response programs		15		15		—
Other		2		—		2


Noncurrent regulatory liabilities		3,492		3,145		317
Over-recovered energy and transmission costs current liability		33		11		22


Total regulatory liabilities	$	3,525	$	3,156	$	339


(a)		These amounts represent estimated future nuclear decommissioning costs that are less than the associated NDT fund assets. These regulatory liabilities have an equal and offsetting noncurrent receivable from affiliate at ComEd and PECO, and a noncurrent payable to affiliate recorded at Generation equal to the total regulatory liability at Exelon, ComEd and PECO. See Note 10 — Nuclear Decommissioning for additional information on the NDT fund activity.

Operating and Maintenance for Regulatory Required Programs (Exelon, ComEd and PECO)

The following tables set forth costs for various legislative and/or regulatory programs that are recoverable from customers on a full and current basis through a reconcilable automatic adjustment clause for ComEd and PECO for the three and six months ended June 30, 2010 and 2009. An equal and offsetting amount has been reflected in operating revenues during the periods.


For the Three Months Ended June 30, 2010	Exelon		ComEd			PECO
Energy efficiency and demand response programs	$	33	$	20	(a)	$	13
Purchased power administrative costs		1		1			—


Total operating and maintenance for regulatory required programs	$	34	$	21		$	13


For the Six Months Ended June 30, 2010	Exelon		ComEd			PECO
Energy efficiency and demand response programs	$	58	$	38	(a)	$	20
Purchased power administrative costs		2		2			—
Consumer education program		1		—			1	(b)


Total operating and maintenance for regulatory required programs	$	61	$	40		$	21


For the Three Months Ended June 30, 2009	Exelon		ComEd
Energy efficiency and demand response programs	$	13	$	13	(a)
Purchased power administrative costs		1		1


Total operating and maintenance for regulatory required programs	$	14	$	14


For the Six Months Ended June 30, 2009	Exelon		ComEd
Energy efficiency and demand response programs	$	23	$	23	(a)
Purchased power administrative costs		2		2


Total operating and maintenance for regulatory required programs	$	25	$	25


(a)		As a result of the Illinois Settlement Legislation, Illinois utilities are required to provide energy efficiency and demand response programs.

(b)		In 2009, the PAPUC authorized PECO to collect a surcharge to recover expenditures associated with PECO’s approved consumer education plan related to the transition to competitive energy market prices.

Fair Value of Financial Assets and Liabilities (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Fair Value of Financial Assets and Liabilities (Exelon, Generation, ComEd and PECO) [Abstract]

Fair Value of Financial Assets and Liabilities (Exelon, Generation, ComEd and PECO)

4. Fair Value of Financial Assets and Liabilities (Exelon, Generation, ComEd and PECO)

Non-Derivative Financial Assets and Liabilities. As of June 30, 2010 and December 31, 2009, the Registrants’ carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, short-term notes payable and accrued liabilities are representative of fair value because of the short-term nature of these instruments.

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Exelon

The carrying amounts and fair values of Exelon’s long-term debt, spent nuclear fuel obligation and preferred securities of subsidiary as of June 30, 2010 and December 31, 2009 were as follows:


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	11,026	$	12,077	$	11,634	$	12,223
Long-term debt of variable interest entity due within one year (a)		404		408		—		—
Long-term debt to PETT due within one year (a)		—		—		415		426
Long-term debt to financing trusts		390		332		390		325
Spent nuclear fuel obligation		1,018		864		1,017		832
Preferred securities of subsidiary		87		70		87		63


(a)		On January 1, 2010, PETT was consolidated in Exelon’s Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 — Basis of Presentation for additional information.

Generation

The carrying amounts and fair values of Generation’s long-term debt and spent nuclear fuel obligations as of June 30, 2010 and December 31, 2009 were as follows:


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	2,779	$	3,021	$	2,993	$	3,132
Spent nuclear fuel obligation		1,018		864		1,017		832

ComEd

The carrying amounts and fair values of ComEd’s long-term debt as of June 30, 2010 and December 31, 2009 were as follows:


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	4,712	$	5,260	$	4,711	$	5,062
Long-term debt to financing trust		206		173		206		167

PECO

The carrying amounts and fair values of PECO’s long-term debt and preferred securities as of June 30, 2010 and December 31, 2009 were as follows:


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	2,221	$	2,461	$	2,221	$	2,346
Long-term debt of variable interest entity due within one year (a)		404		408		—		—
Long-term debt to PETT due within one year (a)		—		—		415		426
Long-term debt to financing trusts		184		159		184		158
Preferred securities		87		70		87		63


(a)		On January 1, 2010, PETT was consolidated in PECO’s Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 — Basis of Presentation for additional information.

Recurring Fair Value Measurements

To increase consistency and comparability in fair value measurements, the FASB established a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows:

•

Level 1 — quoted prices (unadjusted) in active markets for identical assets or liabilities that the Registrants have the ability to access as of the reporting date. Financial assets and liabilities utilizing Level 1 inputs include active exchange-traded equity securities, exchange-based derivatives, mutual funds and money market funds.

•

Level 2 — inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include fixed income securities, non-exchange-based derivatives, commingled investment funds priced at NAV per fund share and fair value hedges.

•

Level 3 — unobservable inputs, such as internally developed pricing models for the asset or liability due to little or no market activity for the asset or liability. Financial assets and liabilities utilizing Level 3 inputs include infrequently traded non-exchange-based derivatives.

Exelon

The following tables present assets and liabilities measured and recorded at fair value on Exelon’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2010 and December 31, 2009:


As of June 30, 2010	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	1,455		$	—		$	—		$	1,455
Nuclear decommissioning trust fund investments
Cash equivalents		53			73			—			126
Equity securities(b)		1,414			—			—			1,414
Commingled funds(c)		—			1,920			—			1,920
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		702			106			—			808
Debt securities issued by states of the United States and political subdivisions of the states		—			440			—			440
Corporate debt securities		—			719			—			719
Federal agency mortgage-backed securities		—			761			—			761
Commercial mortgage-backed securities (non-agency)		—			125			—			125
Residential mortgage-backed securities (non-agency)		—			8			—			8
Other debt obligations		—			74			1			75

Nuclear decommissioning trust fund investments subtotal(d)		2,169			4,226			1			6,396


Rabbi trust investments
Cash equivalents		24			—			—			24
Mutual funds(e)		13			—			—			13

Rabbi trust investments subtotal		37			—			—			37


Mark-to-market derivative assets
Cash flow hedges		—			973			4			977
Other derivatives		3			1,852			72			1,927
Proprietary trading		—			287			47			334
Effect of netting and allocation of collateral received/paid(f)		(6	)		(2,154	)		(33	)		(2,193	)

Mark-to-market assets(g)		(3	)		958			90			1,045


Total assets		3,658			5,184			91			8,933


Liabilities
Mark-to-market derivative liabilities
Cash flow hedges		—			(79	)		(3	)		(82	)
Other derivatives		(3	)		(948	)		(29	)		(980	)
Proprietary trading		—			(282	)		(13	)		(295	)
Effect of netting and allocation of collateral received/paid(f)		3			1,270			22			1,295

Mark-to-market liabilities(g)		—			(39	)		(23	)		(62	)

Deferred compensation		—			(70	)		—			(70	)


Total liabilities		—			(109	)		(23	)		(132	)


Total net assets	$	3,658		$	5,075		$	68		$	8,801


As of December 31, 2009	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	1,845		$	—		$	—		$	1,845
Nuclear decommissioning trust fund investments
Cash equivalents		2			120			—			122
Equity securities(b)		1,528			—			—			1,528
Commingled funds(c)		—			2,086			—			2,086
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		511			119			—			630
Debt securities issued by states of the United States and political subdivisions of the states		—			454			—			454
Corporate debt securities		—			710			—			710
Federal agency mortgage-backed securities		—			887			—			887
Commercial mortgage-backed securities (non-agency)		—			91			—			91
Residential mortgage-backed securities (non-agency)		—			9			—			9
Other debt obligations		—			76			—			76

Nuclear decommissioning trust fund investments subtotal(d)		2,041			4,552			—			6,593


Rabbi trust investments
Cash equivalents		28			—			—			28
Mutual funds(e)		13			—			—			13

Rabbi trust investments subtotal		41			—			—			41


Mark-to-market derivative net (liabilities) assets(f)(g)		(4	)		852			(44	)		804


Total assets (liabilities)		3,923			5,404			(44	)		9,283


Liabilities
Deferred compensation		—			(82	)		—			(82	)
Servicing liability		—			—			(2	)		(2	)


Total liabilities		—			(82	)		(2	)		(84	)


Total net assets	$	3,923		$	5,322		$	(46	)	$	9,199


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 — Basis of Presentation for additional information on the VIE.

(b)		Generation’s NDT funds hold equity portfolios whose performance is benchmarked against the S&P 500 Index, Russell 3000 Index or Morgan Stanley Capital International Europe, Australasia and Far East (EAFE) Index.

(c)		Generation’s NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S&P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.

(d)		Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.

(e)		Excludes $22 million and $23 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009, respectively.

(f)		Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2009.

(g)		The Level 3 balance does not include current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation’s financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010 and a noncurrent asset of $2 million at December 31, 2009, respectively, related to the fair value of Generation’s block contracts with PECO, which eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2010 and 2009:


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of March 31, 2010	$	—	$	33		$	33
Total realized / unrealized gains (losses)
Included in other comprehensive income		—		(11	)(c)		(11	)
Included in regulatory assets		—		1			1
Change in collateral		—		9			9
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		24			24


Balance as of June 30, 2010	$	1	$	67		$	68

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—	$	1		$	1


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Six Months Ended June 30, 2010 (a)	Liability			Investments		Derivatives			Total
Balance as of December 31, 2009	$	(2	)	$	—	$	(44	)	$	(46	)
Total realized / unrealized gains (losses)
Included in income		2	(d)		—		80	(b)		82
Included in other comprehensive income		—			—		7	(c)		7
Included in regulatory assets		—			—		(2	)		(2	)
Change in collateral		—			—		(8	)		(8	)
Purchases, sales, issuances, and settlements
Purchases		—			1		11			12
Transfers out of Level 3 — Liability		—			—		23			23


Balance as of June 30, 2010	$	—		$	1	$	67		$	68

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—		$	—	$	78		$	78


(a)		Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

(b)		Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.

(c)		Excludes increases/(decreases) in fair value of ($121) million and $199 million and realized losses due to settlements of $104 million and $160 million associated with Generation’s financial swap contract with ComEd and ($1) million and $3 million of changes in fair value of Generation’s block contracts with PECO for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

(d)		The servicing liability related to PECO’s accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Three Months Ended June 30, 2009	Liability			Investments		Derivatives			Total
Balance as of March 31, 2009	$	(2	)	$	1,371	$	48		$	1,417
Total realized / unrealized gains (losses)
Included in income		—			98		(33	)(a)		65
Included in other comprehensive income		—			—		(2	)(b)		(2	)
Included in regulatory assets		—			183		(1	)		182
Purchases, sales and issuances, net		—			27		—			27

Balance as of June 30, 2009	$	(2	)	$	1,679	$	12		$	1,689

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	—		$	97	$	(21	)	$	76


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Six Months Ended June 30, 2009	Liability			Investments		Derivatives			Total
Balance as of December 31, 2008	$	(2	)	$	1,220	$	106		$	1,324
Total realized / unrealized gains (losses)
Included in income		—			41		(101	)(a)		(60	)
Included in other comprehensive income		—			—		10	(b)		10
Included in regulatory assets		—			84		(1	)		83
Purchases, sales and issuances, net		—			334		—			334
Transfers into (out of ) Level 3		—			—		(2	)		(2	)

Balance as of June 30, 2009	$	(2	)	$	1,679	$	12		$	1,689

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	—		$	40	$	(71	)	$	(31	)


(a)		Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.

(b)		Excludes increases/(decreases) in fair value of ($85) million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation’s financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All amounts eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

The following tables present total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2010 and 2009:


	Operating		Purchased
	Revenue		Power			Fuel		Other, net
Total gains (losses) included in income for the three months ended June 30, 2010	$	15	$	(20	)	$	5	$	—
Total gains included in income for the six months ended June 30, 2010	$	13	$	36		$	31	$	2
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2010 for the three months ended June 30, 2010	$	20	$	(21	)	$	2	$	—
Change in the unrealized gains relating to assets and liabilities held as of June 30, 2010 for the six months ended June 30, 2010	$	23	$	33		$	22	$	—


	Operating			Purchased
	Revenue			Power			Fuel			Other, net
Total gains (losses) included in income for the three months ended June 30, 2009	$	(21	)	$	(10	)	$	(2	)	$	98
Total gains (losses) included in income for the six months ended June 30, 2009	$	(42	)	$	(6	)	$	(53	)	$	41
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the three months ended June 30, 2009	$	—		$	(9	)	$	(12	)	$	97
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the six months ended June 30, 2009	$	—		$	(7	)	$	(64	)	$	40

Generation

The following tables present assets and liabilities measured and recorded at fair value on Generation’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2010 and December 31, 2009:


As of June 30, 2010	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	790		$	—		$	—		$	790
Nuclear decommissioning trust fund investments
Cash equivalents		53			73			—			126
Equity securities(b)		1,414			—			—			1,414
Commingled funds(c)		—			1,920			—			1,920
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		702			106			—			808
Debt securities issued by states of the United States and political subdivisions of the states		—			440			—			440
Corporate debt securities		—			719			—			719
Federal agency mortgage-backed securities		—			761			—			761
Commercial mortgage-backed securities (non-agency)		—			125			—			125
Residential mortgage-backed securities (non-agency)		—			8			—			8
Other debt obligations		—			74			1			75

Nuclear decommissioning trust fund investments subtotal(d)		2,169			4,226			1			6,396

Rabbi trust investments(e)(f)		4			—			—			4
Mark-to-market derivative assets
Cash flow hedges		—			973			1,019			1,992
Other derivatives		3			1,837			72			1,912
Proprietary trading		—			287			47			334
Effect of netting and allocation of collateral received/paid (g)		(6	)		(2,154	)		(33	)		(2,193	)

Mark-to-market assets(h)		(3	)		943			1,105			2,045


Total assets		2,960			5,169			1,106			9,235


Liabilities
Mark-to-market derivative liabilities
Cash flow hedges		—			(73	)		(3	)		(76	)
Other derivatives		(3	)		(948	)		(25	)		(976	)
Proprietary trading		—			(282	)		(13	)		(295	)
Effect of netting and allocation of collateral received/paid (g)		3			1,270			22			1,295

Mark-to-market liabilities		—			(33	)		(19	)		(52	)

Deferred compensation		—			(19	)		—			(19	)


Total liabilities		—			(52	)		(19	)		(71	)


Total net assets	$	2,960		$	5,117		$	1,087		$	9,164


As of December 31, 2009	Level 1			Level 2			Level 3		Total
Assets
Cash equivalents(a)	$	1,040		$	—		$	—	$	1,040
Nuclear decommissioning trust fund investments
Cash equivalents		2			120			—		122
Equity securities(b)		1,528			—			—		1,528
Commingled funds(c)		—			2,086			—		2,086
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		511			119			—		630
Debt securities issued by states of the United States and political subdivisions of the states		—			454			—		454
Corporate debt securities		—			710			—		710
Federal agency mortgage-backed securities		—			887			—		887
Commercial mortgage-backed securities (non-agency)		—			91			—		91
Residential mortgage-backed securities (non-agency)		—			9			—		9
Other debt obligations		—			76			—		76

Nuclear decommissioning trust fund investments subtotal(d)		2,041			4,552			—		6,593

Rabbi trust investments(e)(f)		4			—			—		4
Mark-to-market derivative net assets(g)(h)		(4	)		842			931		1,769


Total assets		3,081			5,394			931		9,406


Liabilities
Deferred compensation		—			(23	)		—		(23	)


Total liabilities		—			(23	)		—		(23	)


Total net assets	$	3,081		$	5,371		$	931	$	9,383


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b)		Generation’s NDT funds hold equity portfolios whose performance is benchmarked against the S&P 500 Index, Russell 3000 Index or Morgan Stanley Capital International EAFE Index.

(c)		Generation’s NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S&P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.

(d)		Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.

(e)		The mutual funds held by the Rabbi trusts that are invested in common stock of S&P 500 companies and Pennsylvania municipal bonds are primarily rated as investment grade.

(f)		Excludes $7 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.

(g)		Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2009.

(h)		The Level 3 balance includes current and noncurrent assets for Generation of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation’s financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010, respectively, and a noncurrent asset of $2 million at December 31, 2009, related to the fair value of Generation’s block contracts with PECO. All of the mark-to-market balances Generation carries associated with the financial swap contract with ComEd and the block contracts with PECO eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2010 and 2009:


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of March 31, 2010	$	—	$	1,279		$	1,279
Total realized / unrealized losses
Included in other comprehensive income		—		(237	)(c)		(237	)
Change in collateral		—		9			9
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		24			24


Balance as of June 30, 2010	$	1	$	1,086		$	1,087

The amount of total gains included in income attributed to the change in unrealized gains related to assets and liabilities held as of June 30, 2010	$	—	$	1		$	1


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Six Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of December 31, 2009	$	—	$	931		$	931
Total realized / unrealized gains
Included in income		—		80	(b)		80
Included in other comprehensive income		—		49	(c)		49
Change in collateral		—		(8	)		(8	)
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		23			23


Balance as of June 30, 2010	$	1	$	1,086		$	1,087

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—	$	78		$	78


(a)		Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

(b)		Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.

(c)		Includes increases/(decreases) in fair value of ($121) million and $199 million and realized losses due to settlements of $104 million and $160 million associated with Generation’s financial swap contract with ComEd and ($1) million and $3 million of changes in fair value of Generation’s block contracts with PECO for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2009	Investments		Derivatives			Total
Balance as of March 31, 2009	$	1,371	$	1,230		$	2,601
Total realized / unrealized gains (losses)
Included in income		98		(33	)(a)		65
Included in other comprehensive income		—		(146	)(b)		(146	)
Included in noncurrent payables to affiliates		183		—			183
Purchases, sales, issuances and settlements, net		27		—			27

Balance as of June 30, 2009	$	1,679	$	1,051		$	2,730

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	97	$	(21	)	$	76


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Six Months Ended June 30, 2009	Investments		Derivatives			Total
Balance as of December 31, 2008	$	1,220	$	562		$	1,782
Total realized / unrealized gains (losses)
Included in income		41		(101	)(a)		(60	)
Included in other comprehensive income		—		592	(b)		592
Included in noncurrent payables to affiliates		84		—			84
Purchases, sales, issuances and settlements, net		334		—			334
Transfers out of Level 3		—		(2	)		(2	)

Balance as of June 30, 2009	$	1,679	$	1,051		$	2,730

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	40	$	(71	)	$	(31	)


(a)		Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.

(b)		Includes increases/(decreases) in fair value of ($85) million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation’s financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Operating		Purchased
	Revenue		Power			Fuel		Other, net
Total gains (losses) included in income for the three months ended June 30, 2010	$	15	$	(20	)	$	5	$	—
Total gains included in income for the six months ended June 30, 2010	$	13	$	36		$	31	$	—
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2010 for the three months ended June 30, 2010	$	20	$	(21	)	$	2	$	—
Change in the unrealized gains relating to assets and liabilities held as of June 30, 2010 for the six months ended June 30, 2010	$	23	$	33		$	22	$	—


	Operating			Purchased
	Revenue			Power			Fuel			Other, net
Total gains (losses) included in income for the three months ended June 30, 2009	$	(21	)	$	(10	)	$	(2	)	$	98
Total gains (losses) included in income for the six months ended June 30, 2009	$	(42	)	$	(6	)	$	(53	)	$	41
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the three months ended June 30, 2009	$	—		$	(9	)	$	(12	)	$	97
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the six months ended June 30, 2009	$	—		$	(7	)	$	(64	)	$	40

ComEd

The following tables present assets and liabilities measured and recorded at fair value on ComEd’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2010 and December 31, 2009:


As of June 30, 2010	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents (a)	$	7	$	—		$	—		$	7
Rabbi trust investments
Cash equivalents		24		—			—			24


Total assets		31		—			—			31


Liabilities
Deferred compensation obligation		—		(7	)		—			(7	)
Mark-to-market derivative liabilities
Cash flow hedges (b)		—		(6	)		—			(6	)
Other derivatives (c)		—		—			(1,010	)		(1,010	)

Mark-to-market liabilities		—		(6	)		(1,010	)		(1,016	)


Total liabilities		—		(13	)		(1,010	)		(1,023	)


Total net assets (liabilities)	$	31	$	(13	)	$	(1,010	)	$	(992	)


As of December 31, 2009	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents (a)	$	25	$	—		$	—		$	25
Rabbi trust investments
Cash equivalents		28		—			—			28


Total assets		53		—			—			53


Liabilities
Deferred compensation obligation		—		(8	)		—			(8	)
Mark-to-market derivative liabilities (c)		—		—			(971	)		(971	)


Total liabilities		—		(8	)		(971	)		(979	)


Total net assets (liabilities)	$	53	$	(8	)	$	(971	)	$	(926	)


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b)		Cash flow hedges relating to treasury rate locks were recorded in Other current liabilities on ComEd’s Consolidated Balance Sheets.

(c)		The Level 3 balance is comprised of the current and noncurrent liability of $383 million and $627 million at June 30, 2010, respectively, and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of ComEd’s financial swap contract with Generation, which eliminates upon consolidation in Exelon’s Consolidated Financial Statements.

The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2010 and 2009:


	Mark-to-Market
Three Months Ended June 30, 2010	Derivatives
Balance as of March 31, 2010	$	(1,235	)
Total realized / unrealized gains included in regulatory assets (a)		225

Balance as of June 30, 2010	$	(1,010	)


	Mark-to-Market
Six Months Ended June 30, 2010	Derivatives
Balance as of December 31, 2009	$	(971	)
Total realized / unrealized losses included in regulatory assets (a)		(39	)

Balance as of June 30, 2010	$	(1,010	)


(a)		Includes increases/(decreases) in fair value of $121 million and ($199) million and realized gains due to settlements of $104 million and $160 million associated with ComEd’s financial swap contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Mark-to-Market
Three Months Ended June 30, 2009	Derivatives
Balance as of March 31, 2009	$	(1,182	)
Total realized / unrealized gains included in regulatory assets (a)		145

Balance as of June 30, 2009	$	(1,037	)


	Mark-to-Market
Six Months Ended June 30, 2009	Derivatives
Balance as of December 31, 2008	$	(456	)
Total realized / unrealized losses included in regulatory assets (a)		(581	)

Balance as of June 30, 2009	$	(1,037	)


(a)		Includes increases/(decreases) in fair value of $85 million and ($667) million and realized gains due to settlements of $60 million and $86 million associated with ComEd’s financial swap contract with Generation for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

PECO

The following tables present assets and liabilities measured and recorded at fair value on PECO’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of June 30, 2010 and December 31, 2009:


As of June 30, 2010	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	612	$	—		$	—		$	612
Rabbi trust investments — mutual funds(b)(c)		7		—			—			7


Total assets		619		—			—			619


Liabilities
Deferred compensation obligation		—		(22	)		—			(22	)
Mark-to-market derivative liabilities(d)		—		—			(9	)		(9	)


Total liabilities		—		(22	)		(9	)		(31	)


Total net assets (liabilities)	$	619	$	(22	)	$	(9	)	$	588


As of December 31, 2009	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	281	$	—		$	—		$	281
Rabbi trust investments — mutual funds(b)(c)		7		—			—			7


Total assets		288		—			—			288


Liabilities
Deferred compensation obligation		—		(25	)		—			(25	)
Mark-to-market derivative liabilities(d)		—		—			(4	)		(4	)
Servicing liability		—		—			(2	)		(2	)


Total liabilities		—		(25	)		(6	)		(31	)


Total net assets (liabilities)	$	288	$	(25	)	$	(6	)	$	257


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 — Basis of Presentation for additional information on the VIE.

(b)		The mutual funds held by the Rabbi trusts invest in common stock of S&P 500 companies and Pennsylvania municipal bonds that are primarily rated as investment grade.

(c)		Excludes $11 million and $12 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.

(d)		The Level 3 balance is comprised of the current and noncurrent liability of $5 million and $4 million at June 30, 2010, respectively, and the noncurrent liability of $4 million at December 31, 2009, related to the fair value of PECO’s block contracts. These liability balances include a $3 million and $2 million current and noncurrent liability, respectively, at June 30, 2010, and a noncurrent liability of $2 million at December 31, 2009, related to the fair value of PECO’s block contracts with Generation that eliminates upon consolidation in Exelon’s Consolidated Financial Statements.

The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and six months ended June 30, 2010 and 2009:


	Mark-to-Market
Three Months Ended June 30, 2010	Derivatives
Balance as of March 31, 2010	$	(11	)
Total unrealized gains included in regulatory assets		2	(b)

Balance as of June 30, 2010	$	(9	)


	Mark-to-Market
Six Months Ended June 30, 2010	Derivatives			Servicing Liability			Total
Balance as of December 31, 2009	$	(4	)	$	(2	)	$	(6	)
Total realized / unrealized gains (losses)
Included in net income		—			2	(a)		2
Included in regulatory assets		(5	)(b)		—			(5	)

Balance as of June 30, 2010	$	(9	)	$	—		$	(9	)


(a)		The servicing liability related to PECO’s accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.

(b)		Includes increases/(decreases) in fair value of $1 million and ($3) associated with PECO’s block contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Mark-to-Market
Three Months Ended June 30, 2009	Derivatives			Servicing Liability			Total
Balance as of March 31, 2009	$	—		$	(2	)	$	(2	)
Total unrealized losses included in regulatory assets		(2	)		—			(2	)

Balance as of June 30, 2009	$	(2	)	$	(2	)	$	(4	)


	Mark-to-Market
Six Months Ended June 30, 2009	Derivatives			Servicing Liability			Total
Balance as of December 31, 2008	$	—		$	(2	)	$	(2	)
Total unrealized losses included in regulatory assets		(2	)		—			(2	)

Balance as of June 30, 2009	$	(2	)	$	(2	)	$	(4	)

Valuation Techniques Used to Determine Fair Value

The following describes the valuation techniques used to measure the fair value of the assets and liabilities shown in the tables above.

Cash Equivalents (Exelon, Generation, ComEd and PECO). The Registrants’ cash equivalents include investments with maturities of three months or less when purchased. The cash equivalents shown in the fair value tables are comprised of investments in mutual and money market funds. The fair values of the shares of these funds are based on observable market prices and, therefore, have been categorized in Level 1 in the fair value hierarchy.

Nuclear Decommissioning Trust Fund Investments (Exelon and Generation). The trust fund investments have been established to satisfy Exelon’s and Generation’s nuclear decommissioning obligations as required by the NRC. The NDT funds hold debt and equity securities directly and indirectly through commingled funds. Generation’s investment policies place limitations on the types and investment grade ratings of the securities that may be held by the trusts. These policies restrict the trust funds from holding alternative investments and limit the trust funds’ exposures to investments in highly illiquid markets. Investments with maturities of three months or less when purchased, including certain short-term fixed income securities, are considered cash equivalents and included in the recurring fair value measurements hierarchy as Level 1 or Level 2.

With respect to individually held equity securities, the trustees obtain prices from pricing services, whose prices are obtained from direct feeds from market exchanges, which Generation is able to independently corroborate. The fair values of equity securities held directly by the trust funds are based on quoted prices in active markets and are categorized in Level 1. Equity securities held individually are primarily traded on the New York Stock Exchange and NASDAQ-Global Select Market, which contain only actively traded securities due to the volume trading requirements imposed by these exchanges.

For fixed income securities, multiple prices from pricing services are obtained from pricing vendors whenever possible, which enables cross-provider validations in addition to checks for unusual daily movements. A primary price source is identified based on asset type, class or issue for each security. The trustees monitor prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the portfolio managers challenge an assigned price and the trustees determine that another price source is considered to be preferable. Generation has obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, Generation selectively corroborates the fair values of securities by comparison to other market-based price sources. U.S. Treasury securities are categorized as Level 1 because they trade in a highly liquid and transparent market. The fair values of fixed income securities, excluding U.S. Treasury securities, are based on evaluated prices that reflect observable market information, such as actual trade information or similar securities, adjusted for observable differences and are categorized in Level 2.

Commingled funds, which are similar to mutual funds, are maintained by investment companies and hold certain investments in accordance with a stated set of fund objectives. The fair values of short-term commingled funds held within the trust funds, which generally hold short-term fixed income securities and are not subject to restrictions regarding the purchase or sale of shares, are derived from observable prices. The objectives of the remaining commingled funds in which Exelon and Generation invest primarily seek to track the performance of certain equity indices by purchasing equity securities to replicate the capitalization and characteristics of the indices. In general, equity commingled funds are redeemable on the 15th of the month and the last business day of the month; however, the fund manager may designate any day as a valuation date for the purpose of purchasing or redeeming units. Effective December 31, 2009, commingled funds are categorized in Level 2 because the fair value of the funds are based on NAVs per fund share (the unit of account), primarily derived from the quoted prices in active markets on the underlying equity securities. See Note 10 — Nuclear Decommissioning for further discussion on the NDT fund investments.

Rabbi Trust Investments (Exelon, Generation, ComEd and PECO). The Rabbi trusts were established to hold assets related to deferred compensation plans existing for certain active and retired members of Exelon’s executive management and directors. The investments in the Rabbi trusts are included in investments in the Registrants’ Consolidated Balance Sheets. The fair values of the shares of the funds are based on observable market prices and, therefore, have been categorized in Level 1 in the fair value hierarchy.

Mark-to-Market Derivatives (Exelon, Generation, ComEd and PECO). Derivative contracts are traded in both exchange-based and non-exchange-based markets. Exchange-based derivatives that are valued using unadjusted quoted prices in active markets are categorized in Level 1 in the fair value hierarchy. Certain non-exchange-based derivatives are valued using indicative price quotations available through brokers or over-the-counter, on-line exchanges and are categorized in Level 2. These price quotations reflect the average of the bid-ask, mid-point prices and are obtained from sources that the Registrants believe provide the most liquid market for the commodity. The price quotations are reviewed and corroborated to ensure the prices are observable and representative of an orderly transaction between market participants. This includes consideration of actual transaction volumes, market delivery points, bid-ask spreads and contract duration. The remainder of non-exchange-based derivative contracts is valued using the Black model, an industry standard option valuation model. The Black model takes into account inputs such as contract terms, including maturity, and market parameters, including assumptions of the future prices of energy, interest rates, volatility, credit worthiness and credit spread. For non-exchange-based derivatives that trade in liquid markets, such as generic forwards, swaps and options, model inputs are generally observable. Such instruments are categorized in Level 2. The Registrants’ non-exchange-based derivatives are predominately at liquid trading points. For non-exchange-based derivatives that trade in less liquid markets with limited pricing information, such as the financial swap contract between Generation and ComEd, model inputs generally would include both observable and unobservable inputs. These valuations may include an estimated basis adjustment from an illiquid trading point to a liquid trading point for which active price quotations are available. For valuations that include both observable and unobservable inputs, if the unobservable input is determined to be significant to the overall inputs, the entire valuation is categorized in Level 3. This includes derivatives valued using indicative price quotations whose contract tenure extends into unobservable periods. In instances where observable data is unavailable, consideration is given to the assumptions that market participants would use in valuing the asset or liability. This includes assumptions about market risks such as liquidity, volatility and contract duration. Such instruments are categorized in Level 3 as the model inputs generally are not observable. The Registrants consider credit and nonperformance risk in the valuation of derivative contracts categorized in Level 1, 2 and 3, including both historical and current market data in its assessment of credit and nonperformance risk by counterparty. The impacts of credit and nonperformance risk were not material to the financial statements. Transfers in and out of levels are recognized as of the beginning of the month the transfer occurred. Given derivatives categorized within Level 1 are valued using exchange-based quoted prices within observable periods, transfers between level 2 and level 1 generally do not occur. Transfers in and out of level 2 and level 3 generally occur when the contract tenure becomes more observable.

Exelon may utilize fixed-to-floating interest rate swaps, which are typically designated as fair value hedges, as a means to achieve its targeted level of variable-rate debt as a percent of total debt. In addition, the Registrants may utilize interest rate derivatives to lock in interest rate levels in anticipation of future financings. These interest rate derivatives are typically designated as cash flow hedges. Exelon uses a calculation of future cash inflows and estimated future outflows related to the swap agreements, which are discounted and netted to determine the current fair value. Additional inputs to the present value calculation include the contract terms, counterparty credit risk and market parameters such as interest rates and volatility. As these inputs are based on observable data and valuations of similar instruments, the interest rate swaps are categorized in Level 2 in the fair value hierarchy. See Note 6—Derivative Financial Instruments for further discussion on mark-to-market derivatives.

Deferred Compensation Obligations (Exelon, Generation, ComEd and PECO). The Registrants’ deferred compensation plans allow participants to defer certain cash compensation into a notional investment account. The Registrants include such plans in other current and noncurrent liabilities in their Consolidated Balance Sheets. The value of the Registrants’ deferred compensation obligations is based on the market value of the participants’ notional investment accounts. The notional investments are comprised primarily of mutual funds, which are based on observable market prices. However, since the deferred compensation obligations themselves are not exchanged in an active market, they are categorized in Level 2 in the fair value hierarchy.

Servicing Liability (Exelon and PECO). PECO is party to an agreement with a financial institution under which it transferred an undivided interest, adjusted daily, in customer accounts receivables designated under the agreement in exchange for proceeds of $225 million, which PECO accounted for as a sale under previous guidance on accounting for transfers of financial assets. A servicing liability was recorded for the agreement in accordance with the applicable authoritative guidance for servicing of financial assets. The servicing liability was included in other current liabilities in Exelon’s and PECO’s Consolidated Balance Sheets. The fair value of the liability was determined using internal estimates based on provisions in the agreement, which were categorized as Level 3 inputs in the fair value hierarchy. The servicing liability was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.

Debt and Credit Agreements (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Debt and Credit Agreements (Exelon, Generation, ComEd and PECO) [Abstract]

Debt and Credit Agreements (Exelon, Generation, ComEd and PECO)

5. Debt and Credit Agreements (Exelon, Generation, ComEd and PECO)

Short-Term Borrowings

Exelon meets its short-term liquidity requirements primarily through the issuance of commercial paper, Generation and PECO meet their short-term liquidity requirements primarily through the issuance of commercial paper and borrowings from the intercompany money pool and ComEd meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility.

As of June 30, 2010, Exelon Corporate, Generation and PECO had access to unsecured revolving credit facilities with aggregate bank commitments of $957 million, $4.8 billion and $574 million, respectively. On March 25, 2010, ComEd replaced its $952 million credit facility with a new $1 billion unsecured revolving credit facility that extends to March 25, 2013. Borrowings under that credit facility bear interest at a rate that floats daily based upon a prime rate or at a rate fixed for a specified interest period based upon a LIBOR-based rate. Adders of up to 137.5 basis points for prime-based borrowings and 237.5 basis points for LIBOR-based borrowings are added based upon ComEd’s credit rating. As of June 30, 2010, ComEd did not have any borrowings under its credit facility.

Generation, ComEd and PECO had $7 million, $30 million and $30 million, respectively, of additional credit facility agreements with minority and community banks located primarily within ComEd’s and PECO’s service territories, which expire on October 23, 2010. These facilities are solely utilized to issue letters of credit. As of June 30, 2010, letters of credit issued under these agreements totaled $5 million, $26 million and $29 million for Generation, ComEd and PECO, respectively.

Exelon, Generation, ComEd and PECO had the following amounts of commercial paper and credit facility borrowings outstanding at June 30, 2010 and December 31, 2009:


	June 30,		December 31,
	2010		2009
Commercial paper borrowings
Exelon Corporate	$	—	$	—
Generation		—		—
ComEd		289		—
PECO		—		—
Credit facility borrowings
ComEd	$	—	$	155

Issuance of Long-Term Debt

During the six months ended June 30, 2010, there were no issuances of long-term debt.

During the six months ended June 30, 2009, the following long-term debt was issued:

Company

Type

Interest Rate

Maturity

Amount(a)

Use of Proceeds

Generation

Pollution Control Notes

5.00

December 1, 2042

Used to refinance $46 million of unenhanced tax-exempt variable rate debt that was repurchased on February 23, 2009.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2020

Used to repay credit facility borrowings incurred to repurchase bonds.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2017

Used to repay credit facility borrowings incurred to repurchase bonds.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2021

Used to repay credit facility borrowings incurred to repurchase bonds.

PECO

First Mortgage Bonds

5.00

October 1, 2014

250

Used to refinance short-term debt and for other general corporate purposes.


(a)		Excludes unamortized bond discounts.

(b)		Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were remarketed in May 2009 following an earlier repurchase.

Retirement of Long-Term Debt

During the six months ended June 30, 2010, the following long-term debt was retired:

Company

Type

Interest Rate

Maturity

Amount

ComEd

Sinking fund debentures

4.75

December 1, 2011

Generation

Kennett Square Capital Lease

7.83

September 20, 2020

Generation

Montgomery County Series 1994 B Tax Exempt Bonds

Variable

June 1, 2029

Generation

Indiana County Series 2003 A Tax Exempt Bonds

Variable

June 1, 2027

Generation

York County Series 1993 A Tax Exempt Bonds

Variable

August 1, 2016

Company

Type

Interest Rate

Maturity

Amount

Generation

Salem County 1993 Series A Tax Exempt Bonds

Variable

March 1, 2025

Generation

Delaware County Series 1993 A Tax Exempt Bonds

Variable

August 1, 2016

Generation

Montgomery County Series 1996 A Tax Exempt Bonds

Variable

March 1, 2034

Generation

Montgomery County Series 1994 A Tax Exempt Bonds

Variable

June 1, 2029

Exelon

2005 Senior Notes

4.45

June 15, 2010

400

PECO

PETT Transition Bonds

6.52

September 1, 2010

402

During the six months ended June 30, 2009, the following long-term debt was retired:

Company

Type

Interest Rate

Maturity

Amount

Generation

Pollution Control Notes

Variable

December 1, 2042

Generation

Kennett Square Capital Lease

7.83

September 20, 2020

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2020

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2017

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2021

ComEd

First Mortgage Bonds

5.70

January 15, 2009

ComEd

Sinking fund debentures

4.625-4.75

Various

PECO

PETT Transition Bonds

7.65

September 1, 2009

319

PECO

PETT Transition Bonds

6.52

March 1, 2010


(a)		Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were repurchased in May 2009 and subsequently remarketed.

Variable Rate Debt

Under the terms of ComEd’s variable-rate tax-exempt debt agreements, ComEd may be required to repurchase any outstanding debt before its stated maturity unless supported by sufficient letters of credit. If ComEd was required to repurchase the debt, it would reassess its options to obtain new letters of credit or remarket the bonds in a manner that does not require letter of credit support. ComEd has classified amounts outstanding under these debt agreements based on management’s intent and ability to renew or replace the letters of credit, refinance the debt at reasonable terms on a long-term fixed-rate basis or utilize the capacity under existing long-term credit facilities.

Generation had letter of credit facilities that expired during the second quarter of 2010, which were used to enhance the credit of variable-rate long-term tax-exempt bonds totaling $212 million, with maturities ranging from 2016 — 2034. Generation repurchased the $212 million of tax-exempt bonds during June 2010. Generation has the ability to remarket these bonds whenever it determines it to be economically advantageous.

Accounts Receivable Agreement

PECO is party to an agreement with a financial institution under which it transferred an undivided interest, adjusted daily, in its customer accounts receivable designated under the agreement in exchange for proceeds of $225 million, which Exelon and PECO accounted for as a sale under previous guidance on accounting for transfers of financial assets. The accounting guidance was amended, effective for the Registrants on January 1, 2010, and required that this transaction be accounted for as a secured borrowing, as the transferred interest did not meet the criteria of a participating interest as defined under the authoritative guidance. Therefore, on January 1, 2010, the proceeds of $225 million representing the transferred interest in customer accounts receivable previously recorded as a contra-receivable was reclassified to a short-term note payable on Exelon’s and PECO’s Consolidated Balance Sheets. Additionally, the servicing liability of $2 million recorded under the previous guidance was released. As of June 30, 2010, the financial institution’s undivided interest in Exelon’s and PECO’s gross customer accounts receivable was $366 million, which is calculated under the terms of the agreement. Upon termination or liquidation of this agreement, the financial institution will be entitled to recover up to $225 million plus the accrued yield payable from the pool of receivables pledged. This agreement terminates on September 16, 2010 unless extended in accordance with its terms. As of June 30, 2010, PECO was in compliance with the requirements of the agreement. In the event the agreement is not extended, PECO has sufficient short-term liquidity and could seek alternate financing.

Derivative Financial Instruments (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Derivative Financial Instruments (Exelon, Generation, ComEd and PECO) [Abstract]

Derivative Financial Instruments (Exelon, Generation, ComEd and PECO)

6. Derivative Financial Instruments (Exelon, Generation, ComEd and PECO)

The Registrants are exposed to certain risks related to ongoing business operations. The primary risks managed by using derivative instruments are commodity price risk and interest rate risk. To the extent the amount of energy Exelon generates differs from the amount of energy it has contracted to sell, the Registrants are exposed to market fluctuations in the prices of electricity, fossil fuels and other commodities. The Registrants employ established policies and procedures to manage their risks associated with market fluctuations by entering into physical contracts as well as financial derivative contracts including swaps, futures, forwards, options and short-term and long-term commitments to purchase and sell energy and energy-related products. The Registrants believe these instruments, which are classified as either economic hedges or non-derivatives, mitigate exposure to fluctuations in commodity prices. Exposure to interest rate risk exists as a result of the issuance of variable and fixed-rate debt, commercial paper and lines of credit.

Derivative accounting guidance requires that derivative instruments be recognized as either assets or liabilities at fair value. Under these provisions, economic hedges are recognized on the balance sheet at their fair value unless they qualify for the normal purchases and normal sales exception. The Registrants have applied the normal purchases and normal sales scope exception to certain derivative contracts for the forward sale of generation, power procurement agreements, and natural gas supply agreements. For economic hedges that qualify and are designated as cash flow hedges, the portion of the derivative gain or loss that is effective in offsetting the change in value of the underlying exposure is deferred in accumulated OCI and later reclassified into earnings when the underlying transaction occurs. For economic hedges that do not qualify or are not designated as cash flow hedges, changes in the fair value of the derivative are recognized in earnings each period and are classified as other derivatives in the following tables. Non-derivative contracts for access to additional generation and for sales to load-serving entities are accounted for primarily under the accrual method of accounting, which is further discussed in Note 18 of the 2009 Form 10-K. Additionally, Generation is exposed to certain market risks through its proprietary trading activities. The proprietary trading activities are a complement to Generation’s energy marketing portfolio but represent a small portion of Generation’s overall energy marketing activities.

Commodity Price Risk (Exelon, Generation, ComEd and PECO)

Economic Hedging. The Registrants are exposed to commodity price risk primarily relating to changes in the market price of electricity, fossil fuels, and other commodities associated with price movements resulting from changes in supply and demand, fuel costs, market liquidity, weather conditions, governmental regulatory and environmental policies, and other factors. Within Exelon, Generation has the most exposure to commodity price risk. Generation uses a variety of derivative and non-derivative instruments to manage the commodity price risk of its electric generation facilities, including power sales, fuel and energy purchases, and other energy-related products marketed and purchased. In order to manage these risks, Generation may enter into fixed-price derivative or non-derivative contracts to hedge the variability in future cash flows from forecasted sales of energy and purchases of fuel and energy. The objectives for entering into such hedges include fixing the price for a portion of anticipated future electricity sales at a level that provides an acceptable return on electric generation operations, fixing the price of a portion of anticipated fuel purchases for the operation of power plants, and fixing the price for a portion of anticipated energy purchases to supply load-serving customers. The portion of forecasted transactions hedged may vary based upon management’s policies and hedging objectives, the market, weather conditions, operational and other factors. Generation is also exposed to differences between the locational settlement prices of certain economic hedges and the hedged generating units. This price difference is actively managed through other instruments which include financial transmission rights, whose changes in fair value are recognized in earnings each period, and auction revenue rights.

In general, increases and decreases in forward market prices have a positive and negative impact, respectively, on Generation’s owned and contracted generation positions which have not been hedged. Generation hedges commodity risk on a ratable basis over three-year periods. As of June 30, 2010, the percentage of expected generation hedged was 96%-99%, 86%-89%, and 57%-60% for the remainder of 2010, 2011 and 2012, respectively. The percentage of expected generation hedged is the amount of equivalent sales divided by the expected generation. Expected generation represents the amount of energy estimated to be generated or purchased through owned or contracted capacity. Equivalent sales represent all hedging products, which include cash flow hedges, other derivatives and certain non-derivative contracts including sales to ComEd and PECO to serve their retail load.

ComEd has locked in a fixed price for a significant portion of its commodity price risk through the five-year financial swap contract with Generation that expires on May 31, 2013, which is discussed in more detail below. In addition, the contracts that Generation has entered into with ComEd and that ComEd has entered into with Generation and other suppliers as part of the ComEd power procurement agreements, which are further discussed in Note 2 of the 2009 Form 10-K, qualify for the normal purchases and normal sales scope exception. Based on the Illinois Settlement Legislation and ICC-approved procurement methodologies permitting ComEd to recover its electricity procurement costs from retail customers with no mark-up, ComEd’s price risk related to power procurement is limited.

In order to fulfill a requirement of the Illinois Settlement Legislation, Generation and ComEd entered into a five-year financial swap contract effective August 28, 2007. The financial swap is designed to hedge spot market purchases, which along with ComEd’s remaining energy procurement contracts, meet its load service requirements. The remaining swap contract volumes are 3,000 MW from July 2010 through May 2013. The terms of the financial swap contract require Generation to pay the around the clock market price for a portion of ComEd’s electricity supply requirement, while ComEd pays a fixed price. The contract is to be settled net, for the difference between the fixed and market pricing, and the financial terms only cover energy costs and do not cover capacity or ancillary services. The financial swap contract is a derivative financial instrument that has been designated by Generation as a cash flow hedge. Consequently, Generation records the fair value of the swap on its balance sheet and records changes in fair value to OCI. ComEd has not elected hedge accounting for this derivative financial instrument and records the fair value of the swap on its balance sheet. However, since the financial swap contract was deemed prudent by the Illinois Settlement Legislation, ComEd receives full cost recovery for the contract in rates and the change in fair value each period is recorded by ComEd as a regulatory asset or liability. See Note 2 of the 2009 Form 10-K for additional information regarding the Illinois Settlement Legislation. In Exelon’s consolidated financial statements, all financial statement effects of the financial swap recorded by Generation and ComEd are eliminated.

PECO has transferred substantially all of its commodity price risk related to its procurement of electric supply to Generation through a PPA that expires December 31, 2010. The PPA is not considered a derivative under current derivative authoritative guidance. As part of the preparation for the expiration of the PPA, PECO has entered into contracts to procure electric supply through a competitive RFP process as outlined in its PAPUC-approved DSP Program, which is further discussed in Note 3—Regulatory Matters. Based on Pennsylvania legislation and the DSP Program permitting PECO to recover its electric supply procurement costs from retail customers with no mark-up, PECO’s price risk related to electric supply procurement will be limited. PECO will lock in fixed prices for a significant portion of its commodity price risk following the expiration of the electric generation rate caps through full requirements contracts and block contracts. PECO’s full requirements fixed price contracts and block contracts qualify for the normal purchases and normal sales scope exception. For block contracts designated as normal purchases after inception, the mark-to-market balances previously recorded will remain unchanged on PECO’s Consolidated Balance Sheet and will be amortized over the terms of the contracts.

PECO’s natural gas procurement policy is designed to achieve a reasonable balance of long-term and short-term gas purchases under different pricing approaches in order to achieve system supply reliability at the least cost. PECO’s reliability strategy is two-fold. First, PECO must assure that there is sufficient transportation capacity to satisfy delivery requirements. Second, PECO must ensure that a firm source of supply exists to utilize the capacity resources. All of PECO’s natural gas supply and management agreements that are derivatives qualify for the normal purchases and normal sales exception. Additionally, in accordance with the 2009 PAPUC PGC settlement and to reduce the exposure of PECO and its customers to natural gas price volatility, PECO has continued its program to purchase natural gas for both winter and summer supplies using a layered approach of locking-in prices ahead of each season with long-term gas purchase agreements (those with primary terms of at least twelve months). Under the terms of the 2009 PGC settlement, PECO is required to lock in (i.e., economically hedge) the price of a minimum volume of its long-term gas commodity purchases. PECO’s gas-hedging program covers 22% to 29% of planned natural gas purchases in support of projected firm sales. The hedging program for natural gas procurement has no direct impact on PECO’s financial position or results of operations as natural gas costs are fully recovered from customers under the PGC.

Proprietary Trading. Generation also enters into certain energy-related derivatives for proprietary trading purposes. Proprietary trading includes all contracts entered into purely to profit from market price changes as opposed to hedging an exposure and is subject to limits established by Exelon’s RMC. The proprietary trading activities, which included volumes of 889 GWhs and 1,808 GWhs for the three and six months ended June 30, 2010 and 2,003 GWhs and 4,334 GWhs for the three and six months ended June 30, 2009, respectively, are a complement to Generation’s energy marketing portfolio but represent a small portion of Generation’s revenue from energy marketing activities. Neither ComEd nor PECO enter into derivatives for proprietary trading purposes.

Interest Rate Risk (Exelon, Generation and ComEd)

The Registrants use a combination of fixed-rate and variable-rate debt to manage interest rate exposure. The Registrants may also utilize fixed-to-floating interest rate swaps, which are typically designated as fair value hedges, as a means to manage their interest rate exposure. In addition, the Registrants may utilize interest rate derivatives to lock in interest rate levels in anticipation of future financings, which are typically designated as cash flow hedges. These strategies are employed to achieve a lower cost of capital. A hypothetical 10% increase in the interest rates associated with variable-rate debt would result in less than a $1 million decrease in each of Exelon, Generation, and ComEd’s pre-tax income for the three and six months ended June 30, 2010.

Fair Value Hedges. For derivative instruments that are designated and qualify as fair value hedges, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings. Exelon includes the gain or loss on the hedged items and the offsetting loss or gain on the related interest rate swaps in interest expense as follows:


	Gain (Loss) on Swaps					Gain (Loss) on Borrowings
	Six Months Ended					Six Months Ended
	June 30,					June 30,
Income Statement Classification	2010		2009			2010			2009
Interest expense	$	5	$	(6	)	$	(5	)	$	6

At June 30, 2010 and December 31, 2009, Exelon had $100 million of notional amounts of fair value hedges outstanding related to interest rate swaps, with fair value assets of $15 million and $10 million, respectively. During the three and six months ended June 30, 2010 and 2009, there was no impact on the results of operations as a result of ineffectiveness from fair value hedges.

Cash Flow Hedges. In connection with an anticipated debt issuance in the third quarter of 2010, ComEd entered into treasury rate locks in the aggregate notional amount of $300 million in June 2010. ComEd intends to settle the treasury rate locks during the third quarter. Once settled, ComEd will record a regulatory asset or liability and the associated loss or gain will be amortized to income over the life of the related debt as an increase or reduction to interest expense.

Fair Value Measurement (Exelon, Generation, ComEd and PECO)

Fair value accounting guidance requires the fair value of derivative instruments to be shown in the Notes to the Consolidated Financial Statements on a gross basis, even when the derivative instruments are subject to master netting agreements and qualify for net presentation in the Consolidated Balance Sheet. In the table below, Generation’s cash flow hedges, other derivatives and proprietary trading derivatives are shown gross and the impact of the netting of fair value balances with the same counterparty, as well as netting of collateral, is aggregated in the collateral and netting column. Excluded from the tables below are economic hedges that qualify for the normal purchases and normal sales exception and other non-derivative contracts that are accounted for under the accrual method of accounting.

The following table provides a summary of the derivative fair value balances recorded by the Registrants as of June 30, 2010:


	Generation															ComEd									PECO			Other					Exelon
										Collateral
	Cash Flow			Other			Proprietary			and						IL Settlement			Cash Flow						Other			Other		Intercompany			Total
Derivatives	Hedges(a,d)			Derivatives			Trading			Netting(b)			Subtotal(c)			Swap(a)			Hedges(e)			Subtotal			Derivatives (d)			Derivatives		Eliminations(a)			Derivatives

Mark-to-market derivative assets (current assets)	$	581		$	1,085		$	194		$	(1,442	)	$	418		$	—		$	—		$	—		$	—		$	—	$	—		$	418

Mark-to-market derivative assets with affiliate (current assets)		386			—			—			—			386			—			—			—			—			—		(386	)		—

Mark-to-market derivative assets (noncurrent assets)		396			827			140			(751	)		612			—			—			—			—			15		—			627

Mark-to-market derivative assets with affiliate (noncurrent assets)		629			—			—			—			629			—			—			—			—			—		(629	)		—


Total mark-to-market derivative assets	$	1,992		$	1,912		$	334		$	(2,193	)	$	2,045		$	—		$	—		$	—		$	—		$	15	$	(1,015	)	$	1,045


Mark-to-market derivative liabilities (current liabilities)	$	(26	)	$	(691	)	$	(181	)	$	852		$	(46	)	$	—		$	(6	)	$	(6	)	$	(2	)	$	—	$	—		$	(54	)

Mark-to-market derivative liability with affiliate (current liabilities)		—			—			—			—			—			(383	)		—			(383	)		(3	)		—		386			—

Mark-to-market derivative liabilities (noncurrent liabilities)		(50	)		(285	)		(114	)		443			(6	)		—			—			—			(2	)		—		—			(8	)

Mark-to-market derivative liability with affiliate (noncurrent liabilities)		—			—			—			—			—			(627	)		—			(627	)		(2	)		—		629			—


Total mark-to-market derivative liabilities		(76	)		(976	)		(295	)		1,295			(52	)		(1,010	)		(6	)		(1,016	)		(9	)		—		1,015			(62	)


Total mark-to-market derivative net assets (liabilities)	$	1,916		$	936		$	39		$	(898	)	$	1,993		$	(1,010	)	$	(6	)	$	(1,016	)	$	(9	)	$	15	$	—		$	983

(a)

Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.

(b)

Represents the netting of fair value balances with the same counterparty and the application of collateral.

(c)

Current and noncurrent assets are shown net of collateral of $586 million and $309 million, respectively, and current liabilities are shown inclusive of collateral of $3 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received and offset against mark-to-market assets and liabilities was $898 million at June 30, 2010.

(d)

Includes current and noncurrent assets for Generation and current and noncurrent liabilities for PECO of $3 million and $2 million, respectively, related to the fair value of PECO’s block contracts with Generation. There were no netting adjustments or collateral received.

(e)

Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd’s Consolidated Balance Sheets.

The following table provides a summary of the derivative fair value balances recorded by the Registrants as of December 31, 2009:


	Generation															ComEd			PECO			Other					Exelon
										Collateral
	Cash Flow			Other			Proprietary			and						IL Settlement			Other			Other		Intercompany			Total
Derivatives	Hedges(a)			Derivatives			Trading			Netting(b)			Subtotal(c)			Swap(a)			Derivatives (d)			Derivatives		Eliminations(a)			Derivatives

Mark-to-market derivative assets (current assets)	$	576		$	913		$	193		$	(1,306	)	$	376		$	—		$	—		$	—	$	—		$	376

Mark-to-market derivative assets with affiliate (current assets)		302			—			—			—			302			—			—			—		(302	)		—

Mark-to-market derivative assets (noncurrent assets)		423			792			102			(678	)		639			—			—			10		—			649

Mark-to-market derivative assets with affiliate (noncurrent assets)		671			—			—			—			671			—			—			—		(671	)		—


Total mark-to-market derivative assets	$	1,972		$	1,705		$	295		$	(1,984	)	$	1,988		$	—		$	—		$	10	$	(973	)	$	1,025


Mark-to-market derivative liabilities (current liabilities)	$	(18	)	$	(743	)	$	(172	)	$	735		$	(198	)	$	—		$	—		$	—	$	—		$	(198	)

Mark-to-market derivative liability with affiliate (current liabilities)		—			—			—			—			—			(302	)		—			—		302			—

Mark-to-market derivative liabilities (noncurrent liabilities)		(42	)		(183	)		(98	)		302			(21	)		—			(2	)		—		—			(23	)

Mark-to-market derivative liability with affiliate (noncurrent liabilities)		—			—			—			—			—			(669	)		(2	)		—		671			—


Total mark-to-market derivative liabilities		(60	)		(926	)		(270	)		1,037			(219	)		(971	)		(4	)		—		973			(221	)


Total mark-to-market derivative net assets (liabilities)	$	1,912		$	779		$	25		$	(947	)	$	1,769		$	(971	)	$	(4	)	$	10	$	—		$	804


(a)		Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $302 million and $669 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.

(b)		Represents the netting of fair value balances with the same counterparty and the application of collateral.

(c)		Current and noncurrent assets are shown net of collateral of $502 million and $376 million, respectively, and current liabilities are shown inclusive of collateral of $69 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $947 million at December 31, 2009.

(d)		Includes a noncurrent liability for PECO and a noncurrent asset for Generation of $2 million related to the fair value of PECO’s block contracts with Generation. There were no netting adjustments or collateral received as of December 31, 2009.

Cash Flow Hedges (Exelon, Generation and ComEd). Economic hedges that qualify as cash flow hedges primarily consist of forward power sales and power swaps on base load generation. At June 30, 2010, Generation had net unrealized pre-tax gains on effective cash flow hedges of $1,916 million being deferred within accumulated OCI, including approximately $1,010 million related to the financial swap with ComEd. Amounts recorded in accumulated OCI related to changes in energy commodity cash flow hedges are reclassified to results of operations when the forecasted purchase or sale of the energy commodity occurs. Reclassifications from OCI are included in operating revenues, purchased power and fuel in Exelon’s and Generation’s Consolidated Statements of Operations, depending on the commodities involved in the hedged transaction. Based on market prices at June 30, 2010, approximately $941 million of these net pre-tax unrealized gains within accumulated OCI are expected to be reclassified from accumulated OCI during the next twelve months by Generation, including approximately $383 million related to the financial swap with ComEd. However, the actual amount reclassified from accumulated OCI could vary due to future changes in market prices. Generation expects the settlement of the majority of its cash flow hedges will occur during 2010 through 2012, and the ComEd financial swap contract during 2010 through 2013.

At June 30, 2010, ComEd had $6 million of net unrealized pre-tax losses on effective cash flow hedges which were deferred and recorded in accumulated OCI, relating to treasury rate locks.

Exelon discontinues hedge accounting prospectively when it determines that the derivative is no longer effective in offsetting changes in the cash flows of a hedged item, in the case of forward-starting hedges, or when it is no longer probable that the forecasted transaction will occur. For the three and six months ended June 30, 2010, amounts reclassified into earnings as a result of the discontinuance of cash flow hedges were immaterial.

The tables below provide the activity of accumulated OCI related to cash flow hedges for the three and six months ended June 30, 2010 and 2009, containing information about the changes in the fair value of cash flow hedges and the reclassification from accumulated OCI into results of operations. The amounts reclassified from accumulated OCI, when combined with the impacts of the actual physical power sales, result in the ultimate recognition of net revenues at the contracted price.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Three Months Ended June 30, 2010	Location	Hedges			Hedges

Accumulated OCI derivative gain at March 31, 2010		$	1,703	(a)	$	934
Effective portion of changes in fair value			(335	)(b)		(262	)(e)
Reclassifications from accumulated OCI to net income	Operating Revenue		(211	)(c)		(148	)
Ineffective portion recognized in income	Purchased Power		1			1

Accumulated OCI derivative gain at June 30, 2010		$	1,158	(a)(d)	$	525


(a)		Includes $610 million and $746 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $4 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and March 31, 2010, respectively.

(b)		Includes a $73 million loss, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $1 million loss, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the three months ended June 30, 2010.

(c)		Includes a $63 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2010.

(d)		Excludes $5 million gains, net of taxes, related to interest rate swaps settled in 2010.

(e)		Includes $4 million of losses, net of taxes, related to the effective portion of changes in fair value of treasury rate locks at ComEd.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Six Months Ended June 30, 2010	Location	Hedges			Hedges
Accumulated OCI derivative gain at December 31, 2009		$	1,152	(a)	$	551
Effective portion of changes in fair value			334	(b)		205	(e)
Reclassifications from accumulated OCI to net income	Operating Revenue		(328	)(c)		(231	)

Accumulated OCI derivative gain at June 30, 2010		$	1,158	(a,d)	$	525


(a)		Includes $610 million and $585 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $1 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and December 31, 2009, respectively.

(b)		Includes a $122 million gain, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $2 million gain, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the six months ended June 30, 2010.

(c)		Includes a $97 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the six months ended June 30, 2010.

(d)		Excludes $5 million gains, net of taxes, related to interest rate swaps settled in 2010.

(e)		Includes $4 million of losses, net of taxes, related to the effective portion of changes in fair value of treasury rate locks at ComEd.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Three Months Ended June 30, 2009	Location	Hedges			Hedges
Accumulated OCI derivative gain at March 31, 2009		$	1,814	(a)	$	1,110
Effective portion of changes in fair value			(42	)(b)		4
Reclassifications from accumulated OCI to net income	Operating Revenue		(262	)(c)		(226	)
Ineffective portion recognized in income	Purchased Power		2			2

Accumulated OCI derivative gain at June 30, 2009		$	1,512	(a)	$	890


(a)		Includes $624 million and $712 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and March 31, 2009, respectively.

(b)		Includes a $52 million loss, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd during the three months ended June 30, 2009.

(c)		Includes a $36 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2009.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Six Months Ended June 30, 2009	Location	Hedges			Hedges
Accumulated OCI derivative gain at December 31, 2008		$	855	(a)	$	585
Effective portion of changes in fair value			1,059	(b)		654
Reclassifications from accumulated OCI to net income	Operating Revenue		(407	)(c)		(354	)
Ineffective portion recognized in income	Purchased Power		5			5

Accumulated OCI derivative gain at June 30, 2009		$	1,512	(a)	$	890


(a)		Includes $624 million and $275 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and December 31, 2008, respectively.

(b)		Includes a $401 million gain, net of taxes, of the effective portion of changes in fair value of the five-year financial swap contract with ComEd for the six months ended June 30, 2009.

(c)		Includes a $52 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd during the six months ended June 30, 2009.

During the three and six months ended June 30, 2010, Generation’s cash flow hedge activity impact to pre-tax earnings based on the reclassification adjustment from accumulated OCI to earnings was a $349 million and $543 million pre-tax gain, respectively, and a $434 million and $674 million pre-tax gain for the three and six months ended June 30, 2009, respectively. Given that the cash flow hedges primarily consist of forward power sales and power swaps and do not include gas options or sales, the ineffectiveness of Generation’s cash flow hedges is primarily the result of differences between the locational settlement prices of the cash flow hedges and the hedged generating units. This price difference is actively managed through other instruments which include financial transmission rights, whose changes in fair value are recognized in earnings each period, and auction revenue rights. During the three months ended June 30, 2010, cash flow hedge ineffectiveness changed by $1 million primarily due to the change in market prices during the period, none of which was related to Generation’s financial swap contract with ComEd or Generation’s block contracts with PECO. The change in cash flow hedge ineffectiveness for the six months ended June 30, 2010 was not significant. During the three and six months ended June 30, 2009, cash flow hedge ineffectiveness changed by $3 million and $8 million, respectively, primarily due to the change in market prices during the period, none of which was related to Generation’s financial swap contract with ComEd. At June 30, 2010 and December 31, 2009, cash flow hedge ineffectiveness was not significant.

Exelon’s energy-related cash flow hedge activity impact to pre-tax earnings based on the reclassification adjustment from accumulated OCI to earnings was a $245 million and $383 million pre-tax gain for the three and six months ended June 30, 2010, respectively, and a $373 million and $587 million pre-tax gain for the three and six months ended June 30, 2009, respectively. Changes in cash flow hedge ineffectiveness, primarily due to changes in market prices, were $1 million pre-tax for the three months ended June 30, 2010, and $3 million and $8 million pre-tax for the three and six months ended June 30, 2009, respectively. The change in cash flow hedge ineffectiveness for the six months ended June 30, 2010 was not significant.

Other Derivatives (Exelon and Generation). Other derivative contracts are those that do not qualify or are not designated for hedge accounting. These instruments represent economic hedges that mitigate exposure to fluctuations in commodity prices and include financial options, futures, swaps, and forward sales. For the three and six months ended June 30, 2010 and 2009, the following net pre-tax mark-to-market gains (losses) of certain purchase and sale contracts were reported in fuel and purchased power expense at Exelon and Generation in the Consolidated Statements of Operations and Comprehensive Income and are included in “Net fair value changes related to derivatives” in Exelon’s and Generation’s Consolidated Statements of Cash Flows. In the tables below, “Change in fair value” represents the change in fair value of the derivative contracts held at the reporting date. The “Reclassification to realized at settlement” represents the recognized change in fair value that was reclassified to realized due to settlement of the derivative during the period.


	Exelon and Generation
	Purchased
Three Months Ended June 30, 2010	Power			Fuel		Total
Change in fair value	$	(72	)	$	25	$	(47	)
Reclassification to realized at settlement		(77	)		1		(76	)

Net mark-to-market gains (losses)	$	(149	)	$	26	$	(123	)


	Exelon and Generation
	Purchased
Six Months Ended June 30, 2010	Power			Fuel		Total
Change in fair value	$	181		$	73	$	254
Reclassification to realized at settlement		(146	)		1		(145	)

Net mark-to-market gains	$	35		$	74	$	109


	Exelon and Generation
	Purchased
Three Months Ended June 30, 2009	Power			Fuel			Total
Change in fair value	$	(114	)	$	(59	)	$	(173	)
Reclassification to realized at settlement		(50	)		53			3

Net mark-to-market losses	$	(164	)	$	(6	)	$	(170	)


	Exelon and Generation
	Purchased
Six Months Ended June 30, 2009	Power			Fuel			Total
Change in fair value	$	142		$	(102	)	$	40
Reclassification to realized at settlement		(96	)		76			(20	)

Net mark-to-market gains (losses)	$	46		$	(26	)	$	20

Proprietary Trading Activities (Exelon and Generation). For the three and six months ended June 30, 2010 and 2009, Exelon and Generation recognized the following net unrealized mark-to-market gains (losses), net realized mark-to-market gains (losses) and total net mark-to-market gains (losses) (before income taxes) relating to mark-to-market activity on derivative instruments entered into for proprietary trading purposes. Gains and losses associated with proprietary trading are reported as operating revenue in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income and are included in “Net fair value changes related to derivatives” in Exelon’s and Generation’s Consolidated Statements of Cash Flows. In the tables below, “Change in fair value” represents the change in fair value of the derivative contracts held at the reporting date. The “Reclassification to realized at settlement” represents the recognized change in fair value that was reclassified to realized due to settlement of the derivative during the period.


		Three Months Ended						Six Months Ended
	Location on Income	June 30,						June 30,
	Statement	2010			2009			2010			2009
Change in fair value	Operating Revenue	$	19		$	3		$	26		$	3

Reclassification to realized at settlement	Operating Revenue		(6	)		(22	)		(12	)		(43	)


Net mark-to-market gains (losses)	Operating Revenue	$	13		$	(19	)	$	14		$	(40	)

Credit Risk (Exelon, Generation, ComEd and PECO)

The Registrants would be exposed to credit-related losses in the event of non-performance by counterparties that enter into derivative instruments. The credit exposure of derivative contracts, before collateral, is represented by the fair value of contracts at the reporting date. For energy-related derivative instruments, Generation enters into enabling agreements that allow for payment netting with its counterparties, which reduces Generation’s exposure to counterparty risk by providing for the offset of amounts payable to the counterparty against amounts receivable from the counterparty. Typically, each enabling agreement is for a specific commodity and so, with respect to each individual counterparty, netting is limited to transactions involving that specific commodity product, except where master netting agreements exist with a counterparty that allow for cross product netting. In addition to payment netting language in the enabling agreement, Generation’s credit department establishes credit limits, margining thresholds and collateral requirements for each counterparty, which are defined in the derivative contracts. Counterparty credit limits are based on an internal credit review that considers a variety of factors, including the results of a scoring model, leverage, liquidity, profitability, credit ratings and risk management capabilities. To the extent that a counterparty’s margining thresholds are exceeded, the counterparty is required to post collateral with Generation as specified in each enabling agreement. Generation’s credit department monitors current and forward credit exposure to counterparties and their affiliates, both on an individual and an aggregate basis.

The following tables provide information on Generation’s credit exposure for all derivative instruments, normal purchase and normal sales, and applicable payables and receivables, net of collateral and instruments that are subject to master netting agreements, as of June 30, 2010. The tables further delineate that exposure by credit rating of the counterparties and provide guidance on the concentration of credit risk to individual counterparties and an indication of the maturity of a company’s credit risk by credit rating of the counterparties. The figures in the tables below do not include credit risk exposure from uranium procurement contracts or exposure through RTOs, ISOs, NYMEX and ICE commodity exchanges, further discussed in Item 3 — Quantitative and Qualitative Disclosures About Market Risk. Additionally, the figures in the tables below do not include exposures with affiliates, including net receivables with ComEd and PECO of $44 million and $194 million, respectively.


	Total						Number of		Net Exposure of
	Exposure						Counterparties		Counterparties
	Before Credit		Credit		Net		Greater than 10%		Greater than 10%
Rating as of June 30, 2010	Collateral		Collateral		Exposure		of Net Exposure		of Net Exposure
Investment grade	$	1,301	$	452	$	849		—	$	—
Non-investment grade		9		5		4		—		—
No external ratings
Internally rated — investment grade		38		5		33		—		—
Internally rated — non-investment grade		1		1		—		—		—

Total	$	1,349	$	463	$	886		—	$	—


Net Credit Exposure by Type of Counterparty	As of June 30, 2010

Financial institutions	$	307
Investor-owned utilities, marketers and power producers		490
Coal		4
Other		85

Total	$	886

ComEd’s power procurement contracts provide suppliers with a certain amount of unsecured credit. The credit position is based on the price of energy in the spot market compared to the benchmark prices. The benchmark prices are the future prices of energy projected through the contract term and are set at the point of contract execution. If the price of energy in the spot market exceeds the benchmark price, the suppliers are required to post collateral for the secured credit portion. The unsecured credit used by the suppliers represents ComEd’s net credit exposure. As of June 30, 2010, ComEd’s net credit exposure to suppliers was immaterial and either did not exceed the allowed unsecured credit levels or did not exceed the allowed unsecured credit levels by an amount necessary to trigger a collateral call.

ComEd is permitted to recover its costs of procuring energy through the Illinois Settlement Legislation as well as the ICC-approved procurement tariffs. ComEd’s counterparty credit risk is mitigated by its ability to recover realized energy costs through customer rates. See Note 2 of the 2009 Form 10-K for further information.

PECO has a PPA with Generation under which Generation has agreed to supply PECO with all of PECO’s electric supply needs through 2010 at prices that are below current market prices. The price for this electricity is essentially equal to the energy revenues earned from customers. PECO could be negatively affected if Generation could not perform under the PPA.

PECO’s supplier master agreements that govern the terms of its DSP Program contracts, which define a supplier’s performance assurance requirements, allow a supplier to meet its credit requirements with a certain amount of unsecured credit. The amount of unsecured credit is determined based on the supplier’s lowest credit rating from S&P, Fitch or Moody’s and the supplier’s tangible net worth. The credit position is based on the initial market price, which is the forward price of energy on the day a transaction is executed, compared to the current forward price curve for energy. To the extent that the forward price curve for energy exceeds the initial market price, the supplier is required to post collateral to the extent the credit exposure is greater than the supplier’s unsecured credit limit. As of June 30, 2010, PECO’s net credit exposure to suppliers was immaterial and either did not exceed the allowed unsecured credit levels or did not exceed the allowed unsecured credit levels by an amount necessary to trigger a collateral call.

PECO is permitted to recover its costs of procuring electric generation following the expiration of its electric generation rate caps on December 31, 2010 through its PAPUC-approved DSP Program. PECO’s counterparty credit risk is mitigated by its ability to recover realized energy costs through customer rates. See Note 3 — Regulatory Matters for further information.

PECO’s natural gas procurement plan is reviewed and approved annually on a prospective basis by the PAPUC. PECO’s counterparty credit risk under its natural gas supply and asset management agreements is mitigated by its ability to recover its natural gas costs through the PGC, which allows PECO to adjust rates quarterly to reflect realized natural gas prices. PECO does not obtain collateral from suppliers under its natural gas supply and management agreements. As of June 30, 2010, PECO had credit exposure of $8 million under its natural gas supply and management agreements.

Collateral and Contingent-Related Features (Exelon, Generation, ComEd, and PECO)

As part of the normal course of business, Generation routinely enters into physical or financially settled contracts for the purchase and sale of electric capacity, energy, fuels and emissions allowances. Certain of Generation’s derivative instruments contain provisions that require Generation to post collateral. This collateral may be posted in the form of cash or credit support with thresholds contingent upon Generation’s credit rating from each of the major credit rating agencies. The collateral and credit support requirements vary by contract and by counterparty. These credit-risk-related contingent features stipulate that if Generation were to be downgraded or lose its investment grade credit rating (based on its senior unsecured debt rating), it would be required to provide additional collateral. This incremental collateral requirement allows for the offsetting of derivative instruments that are assets with the same counterparty, where the contractual right of offset exists under applicable master netting agreements. Generation also enters into commodity transactions on NYMEX and ICE. The NYMEX and ICE clearing houses act as the counterparty to each trade. Transactions on NYMEX and ICE must adhere to comprehensive collateral and margining requirements.

The aggregate fair value of all derivative instruments with credit-risk-related contingent features in a liability position that are not fully collateralized (excluding transactions on NYMEX and ICE that are fully collateralized) was $945 million and $894 million as of June 30, 2010 and December 31, 2009, respectively. As of June 30, 2010 and December 31, 2009, Generation had the contractual right of offset of $913 million and $778 million, respectively, related to derivative instruments that are assets with the same counterparty under master netting agreements, resulting in a net liability position of $32 million and $116 million, respectively. If Generation had been downgraded to the investment grade rating of BBB- and Baa3, or lost its investment grade credit rating, it would have been required to provide incremental collateral of approximately $57 million or $994 million, respectively, as of June 30, 2010 and approximately $60 million or $673 million, respectively, as of December 31, 2009 related to its financial instruments, including derivatives, non-derivatives, normal purchase normal sales contracts and applicable payables and receivables, net of the contractual right of offset under master netting agreements and the application of collateral. See Note 18 of the 2009 Form 10-K for further information regarding the letters of credit supporting the cash collateral.

Beginning in 2007, under the Illinois auction rules and the SFC that ComEd entered into with counterparty suppliers, including Generation, collateral postings are one-sided from suppliers. Generation entered into similar supplier forward contracts with other utilities, including PECO, with one-sided collateral postings only from Generation. If market prices fall below the benchmark price levels in these contracts, the utilities are not required to post collateral. However, when market prices rise above benchmark price levels, counterparty suppliers, including Generation, are required to post collateral once certain unsecured credit limits are exceeded. Under the terms of the five-year financial swap contract between Generation and ComEd, if a party is downgraded below investment grade by Moody’s or S&P, collateral postings would be required by that party depending on how market prices compare to the benchmark price levels. Under the terms of the financial swap contracts, collateral postings will never exceed $200 million from either ComEd or Generation. Beginning in June 2009, under the terms of ComEd’s standard block energy contracts, collateral postings are one-sided from suppliers, including Generation, should exposures between market prices and benchmark prices exceed established unsecured credit limits outlined in the contracts. As of June 30, 2010, there was an immaterial amount of cash collateral and letters of credit posted by energy suppliers to ComEd associated with energy procurement contracts. See Note 2 of the 2009 Form 10-K for further information.

There are no collateral-related provisions included in the PPA between PECO and Generation. PECO’s supplier master agreements that govern the terms of its DSP Program contracts do not contain provisions that would require PECO to post collateral.

PECO’s natural gas procurement contracts contain provisions that could require PECO to post collateral. This collateral may be posted in the form of cash or credit support with thresholds contingent upon PECO’s credit rating from Moody’s and S&P. The collateral and credit support requirements vary by contract and by counterparty. As of June 30, 2010, PECO was not required to post collateral for any of these agreements. If PECO lost its investment grade credit rating as of June 30, 2010, PECO could have been required to post approximately $46 million of collateral to its counterparties.

Exelon’s interest rate swaps contain provisions that, in the event of a merger, require that Exelon’s debt maintain an investment grade credit rating from Moody’s or S&P. If Exelon’s debt were to fall below investment grade, it would be in violation of these provisions, resulting in the ability of the counterparty to terminate the agreement prior to maturity. Collateralization would not be required under any circumstance. Termination of the agreement could result in a settlement payment by Exelon or the counterparty on any interest rate swap in a net liability position. The settlement amount would be equal to the fair value of the swap on the termination date. As of June 30, 2010, Exelon’s interest rate swap was in an asset position, with a fair value of $15 million.

Accounting for the Offsetting of Amounts Related to Certain Contracts (Exelon and Generation)

As of June 30, 2010 and December 31, 2009, $1 million and $6 million, respectively, of cash collateral received was not offset against net derivative positions, because they were not associated with energy-related derivatives.

Retirement Benefits (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Pension and Other Postretirement Benefit Expense [Abstract]

Retirement Benefits (Exelon, Generation, ComEd and PECO)

7. Retirement Benefits (Exelon, Generation, ComEd and PECO)

Exelon sponsors defined benefit pension plans and postretirement benefit plans for essentially all Generation, ComEd, PECO and BSC employees.

Defined Benefit Pension and Other Postretirement Benefits

During the first quarter of 2010, Exelon received an updated valuation of its pension and other postretirement benefit obligations to reflect actual census data as of January 1, 2010. This valuation resulted in an increase to the pension obligations of $13 million and a decrease to other postretirement obligations of $18 million. Additionally, accumulated other comprehensive loss increased by approximately $18 million (after tax).

The following tables present the components of Exelon’s net periodic benefit costs for the three and six months ended June 30, 2010 and 2009. The 2010 pension benefit cost is calculated using an expected long-term rate of return on plan assets of 8.50%. The 2010 other postretirement benefit cost is calculated using an expected long-term rate of return on plan assets of 7.83%. A portion of the net periodic benefit cost is capitalized within the Consolidated Balance Sheets.


							Other Postretirement
	Pension Benefits						Benefits
	Three Months Ended						Three Months Ended
	June 30,						June 30,
	2010			2009			2010			2009
Service cost	$	49		$	45		$	31		$	28
Interest cost		165			162			53			50
Expected return on assets		(200	)		(194	)		(27	)		(23	)
Amortization of:
Transition obligation		—			—			2			3
Prior service cost (benefit)		3			3			(14	)		(14	)
Actuarial loss		63			49			19			22


Net periodic benefit cost	$	80		$	65		$	64		$	66


							Other Postretirement
	Pension Benefits						Benefits
	Six Months Ended						Six Months Ended
	June 30,						June 30,
	2010			2009			2010			2009
Service cost	$	96		$	89		$	62		$	56
Interest cost		330			325			107			102
Expected return on assets		(400	)		(388	)		(54	)		(47	)
Amortization of:
Transition obligation		—			—			4			5
Prior service cost (benefit)		7			7			(28	)		(28	)
Actuarial loss		127			98			37			44


Net periodic benefit cost	$	160		$	131		$	128		$	132

The following amounts were included in capital additions and operating and maintenance expense during the three and six months ended June 30, 2010 and 2009, for Generation’s, ComEd’s, PECO’s and BSC’s allocated portion of the pension and postretirement benefit plans:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
Pension and Postretirement Benefit Costs	2010		2009		2010		2009
Generation	$	67	$	59	$	134	$	119
ComEd		53		48		106		96
PECO		12		12		24		24
BSC(a)		12		12		24		24


(a)		These amounts primarily represent amounts billed to Exelon’s subsidiaries through intercompany allocations.

Exelon expects to contribute approximately $954 million to the benefit plans in 2010, of which Generation, ComEd and PECO expect to contribute $446 million, $310 million and $103 million, respectively. These amounts include an expected incremental contribution to Exelon’s largest pension plan of approximately $500 million above the expectation at December 31, 2009.

Plan Assets

Investment Strategy. On a regular basis, Exelon evaluates its investment strategy to ensure that plan assets will be sufficient to pay plan benefits when due. As part of this ongoing evaluation, Exelon may make changes to its targeted asset allocation and investment strategy.

In the second quarter of 2010, Exelon modified its pension investment strategy in order to reduce the volatility of its pension assets relative to its pension liabilities. As a result of this modification, over time, Exelon determined that it will decrease equity investments and increase investments in fixed income securities and alternative investments in order to achieve a balanced portfolio of risk-reducing and return-seeking assets. The overall objective is to achieve attractive risk-adjusted returns that will balance the liquidity requirements of the plans’ liabilities while striving to minimize the risk of significant losses. Over the next several years, Exelon expects to migrate to a target asset allocation of approximately 30% public equity investments, 50% fixed income investments and 20% alternative investments.

The change in the overall investment strategy would tend to lower the expected rate of return on plan assets in future years as compared to the previous strategy.

Securities Lending Programs. The majority of the benefit plans participate in a securities lending program with the trustees of the plans’ investment trusts. The program authorizes the trustee of the particular trust to lend securities, which are assets of the plan, to approved borrowers. Borrowers have the right to sell or re-pledge the loaned securities. The trustees require borrowers, pursuant to a security lending agreement, to deliver collateral to secure each loan. The loaned securities are required to be collateralized by cash, U.S. Government securities or irrevocable bank letters of credit. Initial collateral levels are no less than 102% and 105% of the market value of the borrowed securities for collateral denominated in U.S. and foreign currency, respectively. Subsequent collateral levels, which are adjusted daily, must be maintained at a level no less than 100% of the market value of borrowed securities. Cash collateral received is invested in collateral funds comprised primarily of short term investment vehicles and may not be sold or re-pledged by the trustees unless the borrower defaults. Exelon’s benefit plans bear the risk of loss with respect to unfavorable changes in the fair value of the invested cash collateral. Such losses may result from a decline in the fair value of specific investments or due to liquidity impairments resulting from current market conditions. Exelon, the trustees and the borrowers have the right to terminate the lending agreement at any time. In the event of termination, the borrowers must return the loaned securities or surrender the collateral. Losses recognized by the trust were not material during the six months ended June 30, 2010 and 2009. Management continues to monitor the performance of the invested collateral and work closely with the trustees to limit any potential losses.

In 2008, Exelon initiated a gradual withdrawal of the trusts’ investments in order to minimize potential losses due to liquidity constraints in the market. Currently, the weighted average maturity of the securities within the collateral funds is approximately 5 months. The fair value of securities on loan was approximately $121 million and $356 million at June 30, 2010 and December 31, 2009, respectively. The fair value of cash and non-cash collateral received for these loaned securities was $124 million at June 30, 2010 and $365 million at December 31, 2009. A portion of the income generated through the investment of cash collateral is remitted to the borrowers, and the remainder is allocated between the trusts and the trustees in their capacity as security agents. Exelon continues to assess its participation in securities lending programs.

Health Care Reform Legislation (Exelon, Generation, ComEd and PECO)

In March 2010, the Health Care Reform Acts were signed into law. A number of provisions in the Health Care Reform Acts impact retiree health care plans provided by employers. One such provision reduces the deductibility, for Federal income tax purposes, of retiree health care costs to the extent an employer’s postretirement health care plan receives Federal subsidies that provide retiree prescription drug benefits at least equivalent to Medicare prescription drug benefits. Although this change does not take effect immediately, the Registrants were required to recognize the full accounting impact in their financial statements in the period in which the legislation was enacted. As a result, in the first quarter of 2010, Exelon recorded total after-tax charges of approximately $65 million to income tax expense to reverse deferred tax assets previously established. Of this total, Generation, ComEd and PECO recorded charges of $24 million, $11 million and $9 million, respectively.

Additionally, the Health Care Reform Acts contain other provisions that will impact Exelon’s obligation for retiree medical benefits. In particular, the Health Care Reform Acts include a provision that imposes an excise tax on certain high-cost plans beginning in 2018, whereby premiums paid over a prescribed threshold will be taxed at a 40% rate. Exelon does not currently believe the excise tax or other provisions of the Health Care Reform Acts will materially increase its postretirement benefit obligation. Accordingly, a re-measurement of Exelon’s postretirement benefit obligation is not required at this time. However, Exelon will continue to monitor and assess the impact of the Health Care Reform Acts, including any clarifying regulations issued to address how the provisions are to be implemented, on its future results of operations, cash flows or financial position.

401(k) Savings Plan

The Registrants participate in a 401(k) savings plan sponsored by Exelon. The plan allows employees to contribute a portion of their income in accordance with specified guidelines. The Registrants match a percentage of the employee contributions up to certain limits. The following table presents the cost of matching contributions to the savings plans for the Registrants during the three and six months ended June 30, 2010 and 2009:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
Savings Plan Matching Contributions	2010		2009		2010		2009
Exelon	$	20	$	18	$	40	$	36
Generation		10		9		21		18
ComEd		6		5		11		10
PECO		2		2		4		4

Corporate Restructuring and Plant Retirements (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Corporate Restructuring and Plant Retirements (Exelon, Generation, ComEd and PECO) [Abstract]

Corporate Restructuring and Plant Retirements (Exelon, Generation, ComEd and PECO)

8. Corporate Restructuring and Plant Retirements (Exelon, Generation, ComEd and PECO)

The Registrants provide severance and health and welfare benefits to terminated employees primarily based upon each individual employee’s years of service and compensation level. The Registrants accrue amounts associated with severance benefits that are considered probable and that can be reasonably estimated.

Corporate restructuring (Exelon, Generation, ComEd and PECO). In June 2009, Exelon announced a restructured senior executive team and major spending cuts, including the elimination of approximately 500 employee positions. Exelon eliminated approximately 400 corporate support positions, mostly located at corporate headquarters, and 100 management level positions at ComEd, the majority of which was completed by September 30, 2009. These actions were in response to the continuing economic challenges confronting all parts of Exelon’s business and industry especially in light of the commodity-driven nature of Generation’s markets, necessitating continued focus on cost management through enhanced efficiency and productivity.

Exelon recorded a pre-tax charge for estimated salary continuance and health and welfare severance benefits of $40 million in June 2009 as a result of the planned job reductions. Subsequent to June 2009, Exelon recorded a net pre-tax credit of approximately $6 million, which included a $10 million reduction in estimated salary continuance and health and welfare severance benefits, offset by $4 million of expense for contractual termination benefits. Cash payments under the plan began in July 2009 and will continue through 2010. Substantially all cash payments are expected to be made by the end of 2010 resulting in the completion of the corporate restructuring plan.

The following tables present total severance benefits costs, recorded as operating and maintenance expense in relation to the announced job reductions, for the three and six months ended June 30, 2009:


Severance Benefits	Generation		ComEd		PECO		Other		Exelon
Expense recorded for the three and six months ended June 30, 2009 (a)(b)	$	15	$	18	$	5	$	2	$	40


(a)		The amounts above include $8 million, $5 million and $3 million at Generation, ComEd and PECO, respectively, for amounts billed through intercompany allocations.

(b)		The severance benefits costs include $1 million of stock compensation expense collectively at Generation and ComEd for which the obligation is recorded in equity.

The following table presents the activity of severance obligations for the corporate restructuring from December 31, 2009 through June 30, 2010, excluding obligations recorded in equity:


Severance Benefits Obligation	Generation			ComEd			PECO			Other			Exelon
Balance at December 31, 2009	$	3		$	7		$	1		$	8		$	19
Cash payments		(2	)		(5	)		(1	)		(2	)		(10	)

Balance at June 30, 2010	$	1		$	2		$	—		$	6		$	9

Plant Retirements (Exelon and Generation). On December 2, 2009, Exelon announced its intention to permanently retire three coal-fired generating units and one oil/gas-fired generating unit, effective May 31, 2011. The units to be retired are Cromby Generating Station (Cromby) Unit 1 and Unit 2 and Eddystone Generating Station (Eddystone) Unit 1 and Unit 2. These actions were in response to the economic outlook related to the continued operation of these four units. On February 1, 2010, Generation notified PJM that, to the extent the retirement of these units results in reliability impacts, Generation would continue operations beyond its desired deactivation date while construction of the necessary transmission upgrades were made, provided that Exelon receives the required environmental permits and adequate cost-based compensation. On March 2, 2010, PJM determined that transmission reliability upgrades will be necessary to alleviate reliability impacts. During May 2010, PJM updated its analysis and determined that reliability upgrades will be completed to support Generation’s retirement of the units on the following schedule: Cromby Unit 1 and Eddystone Unit 1 on May 31, 2011; Cromby Unit 2 on December 31, 2011; and Eddystone Unit 2 on December 31, 2012. These dates are dependent upon the completion of required transmission reliability upgrades and may be subject to further change. Generation revised the depreciable useful lives for these affected units to reflect the aforementioned anticipated deactivation dates. On June 10, 2010, Generation filed with FERC a reliability-must-run rate schedule providing the terms, conditions and cost-based rates under which Generation will continue to operate the units for reliability purposes beyond their planned May 31, 2011 deactivation date. Under the reliability-must-run rate schedule, which is subject to FERC approval, the total compensation would be approximately $8 million and $3 million of monthly fixed-cost recovery for Generation during the reliability-must-run period for Eddystone Unit 2 and Cromby Unit 2, respectively. Such revenue is intended to recover total expected operating costs, plus a return on net assets, of the two units during the reliability-must-run period. In connection with these retirements, Exelon will eliminate approximately 280 employee positions, the majority of which are located at the units to be retired. Total expected costs for Generation related to the announced retirements is $37 million, which includes $15 million for estimated salary continuance and health and welfare severance benefits, a $17 million write down of inventory and $5 million of shut down costs. Cash payments under this plan began in January 2010 and will continue through 2013. Additionally, total expected accelerated depreciation expense is approximately $200 million.

During 2009, Generation recorded a pre-tax charge of $24 million related to the announced retirements, which included a $7 million charge for estimated salary continuance and health and welfare severance benefits, and $17 million of expense for the write down of inventory recorded within operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations. Additionally, during 2009, Generation recorded $32 million of accelerated depreciation expense within depreciation and amortization expense in Exelon’s and Generation’s Consolidated Statements of Operations. During the three months ended June 30, 2010, Generation recorded $20 million of accelerated depreciation expense. During the six months ended June 30, 2010, Generation recorded a pre-tax credit of $2 million for a reduction in estimated salary continuance and health and welfare severance benefits, and $35 million of accelerated depreciation expense.

The following table presents the activity of severance obligations for the announced Cromby and Eddystone retirements from December 31, 2009 through June 30, 2010:


	Exelon and
Severance Benefits Obligation	Generation
Balance at December 31, 2009	$	7
Cash payments		(1	)
Other adjustments		(2	)

Balance at June 30, 2010	$	4

Income Taxes (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Income Taxes (Exelon, Generation, ComEd and PECO) [Abstract]

Income Taxes (Exelon, Generation, ComEd and PECO)

9. Income Taxes (Exelon, Generation, ComEd and PECO)

The effective income tax rate from continuing operations varies from the U.S. Federal statutory rate principally due to the following:


For the Three Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		3.3			2.9			11.2			(6.8	)
Qualified nuclear decommissioning trust fund losses		(6.7	)		(10.0	)		—			—
Domestic production activities deduction		(2.4	)		(3.4	)		—			—
Tax exempt income		(0.2	)		(0.2	)		—			—
Amortization of investment tax credit		(0.3	)		(0.2	)		(0.4	)		(0.5	)
Plant basis differences		—			—			(0.4	)		0.4
Uncertain Tax Position Remeasurement		—			(14.9	)		47.9			—
Other		(0.4	)		(0.8	)		(0.2	)		(0.2	)


Effective income tax rate		28.3	%		8.4	%		93.1	%		27.9	%


For the Six Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		3.6			4.1			7.6			(6.0	)
Qualified nuclear decommissioning trust fund losses		(0.7	)		(1.0	)		—			—
Domestic production activities deduction		(2.1	)		(2.9	)		—			—
Tax exempt income		(0.2	)		(0.2	)		—			—
Health Care Reform Legislation (a)		3.0			1.5			2.7			2.9
Amortization of investment tax credit		(0.2	)		(0.2	)		(0.4	)		(0.4	)
Plant basis differences		—			—			(0.2	)		0.2
Uncertain Tax Position Remeasurement		—			(4.5	)		18.3			—
Other		(0.2	)		(0.3	)		0.2			(0.2	)


Effective income tax rate		38.2	%		31.5	%		63.2	%		31.5	%


(a)		See Note 7 for further discussion regarding the impact of Health Care Reform Legislation on income tax expense.


For the Three Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		—			0.7			4.6			(4.0	)
Qualified nuclear decommissioning trust fund income		5.7			7.3			—			—
Domestic production activities deduction		(0.9	)		(1.1	)		—			—
Tax exempt income		(0.1	)		(0.1	)		—			—
Nontaxable postretirement benefits		(0.2	)		(0.2	)		(0.4	)		(0.2	)
Amortization of investment tax credit		(0.1	)		(0.1	)		(0.5	)		(0.4	)
Plant basis differences		—			—			(0.3	)		0.1
Other		0.2			(0.6	)		0.2			(0.1	)


Effective income tax rate		39.6	%		40.9	%		38.6	%		30.4	%


For the Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		(0.1	)		0.5			(0.7	)		(5.4	)
Qualified nuclear decommissioning trust fund income		1.9			2.6			—			—
Domestic production activities deduction		(1.2	)		(1.6	)		—			—
Tax exempt income		(0.1	)		(0.2	)		—			—
Nontaxable postretirement benefits		(0.3	)		(0.2	)		(0.5	)		(0.3	)
Amortization of investment tax credit		(0.2	)		(0.1	)		(0.5	)		(0.4	)
Plant basis differences		—			—			(0.3	)		0.3
Other		0.1			(0.3	)		(0.1	)		0.1


Effective income tax rate		35.1	%		35.7	%		32.9	%		29.3	%

Accounting for Uncertainty in Income Taxes

Exelon, Generation, ComEd and PECO have $1.7 billion, $597 million, $467 million and $601 million, respectively, of unrecognized tax benefits as of June 30, 2010. Exelon’s, Generation’s, ComEd’s and PECO’s uncertain tax positions have not significantly changed since December 31, 2009, except for those relating to the 1999 sale of fossil generating assets and competitive transition charges discussed below. See Note 10 of the 2009 Form 10-K for further discussion of reasonably possible changes that could occur in our unrecognized tax benefits during the next twelve months.

Illinois Replacement Investment Tax Credits (Exelon, Generation and ComEd)

On February 20, 2009, the Illinois Supreme Court ruled in Exelon’s favor in a case involving refund claims for Illinois investment tax credits. Responding to the Illinois Attorney General’s petition for rehearing, on July 15, 2009, the Illinois Supreme Court modified its opinion to indicate that it was to be applied only prospectively, beginning in 2009. In September 2009, the Illinois Supreme Court denied Exelon’s Petition for Rehearing.

On December 22, 2009, Exelon filed a Petition of Writ for Certiorari with the United States Supreme Court appealing the Illinois Supreme Court’s July 15, 2009 modified opinion. As a result of the filing of the United States Supreme Court petition, unrecognized tax benefits continued to be reported as of December 31, 2009. On March 1, 2010, the United States Supreme Court announced that it would not review the Illinois Supreme Court’s decision. As a result of the United States Supreme Court decision, Exelon, Generation and ComEd ceased reporting their unrecognized tax benefits as of March 31, 2010.

Tax Method of Accounting for Repairs (Exelon and Generation)

In 2009, Exelon received approval from the IRS to change its method of accounting for repair costs associated with Generation’s power plants. The new tax method of accounting resulted in net positive cash flow for 2009 of approximately $420 million. Although the IRS granted Exelon approval to change its method of accounting, the approval did not affirm the methodology used to calculate the deduction. Exelon had requested and received approval from the IRS to review its methodology through its Pre-Filing Agreement program. However in the second quarter of 2010 Exelon was informed that the IRS has suspended the pre-filing agreement process and instead intends to issue broad industry guidance with respect to electric generation power plants. If that broader guidance is issued, it is reasonably possible that the total amount of unrecognized tax benefits could increase or decrease within the next 12 months.

Nuclear Decommissioning Liabilities (Exelon and Generation)

AmerGen filed income tax refund claims taking the position that nuclear decommissioning liabilities assumed as part of its acquisition of nuclear power plants are taken into account in determining the tax basis in the assets it acquired. The additional basis results primarily in reduced capital gains or increased capital losses on the sale of assets in nonqualified decommissioning funds and increased tax depreciation and amortization deductions. The IRS disagrees with this position and has disallowed the claims. In November of 2008, Generation received a final determination from the Appeals division of the IRS (IRS Appeals) disallowing AmerGen’s refund claims. On February 20, 2009, Generation filed a complaint in the United States Court of Federal Claims to contest this determination. In August 2009, the United States Department of Justice (DOJ) filed its answer denying the allegations made by Generation in its complaint. No trial date has yet been assigned, but trial could occur sometime in 2011.

The trial judge assigned to the case has noted the availability of the court’s Alternative Dispute Resolution (ADR) program as an alternative to a trial, but the parties have not yet met with the ADR judge. The ADR program is a non-binding process that utilizes a variety of techniques such as mediation, neutral evaluation, and non-binding arbitration that allow the parties to better understand their differences and their prospects for settlement. The DOJ presently refuses to commit to participate in ADR. As a result, it is unclear whether ADR will occur and if so, when.

In addition, in the second quarter of 2010, Entergy Corporation concluded its trial in the United States Tax Court of a similar dispute involving the assumption of decommissioning liabilities in connection with the purchase of a nuclear power plant. It is possible that a decision will be reached in this case in the next twelve months. While the decision in this case would not serve as binding precedent for AmerGen’s litigation in the United States Court of Federal Claims, the reasoning of the decision may cause Generation to reevaluate the total amount of unrecognized tax benefits. Due to the possibility of quicker resolution through the ADR program and the possibility of a decision being entered in the Entergy trial, and the lesser prospect of a resolution through ADR, Generation believes that it is reasonably possible that the total amount of unrecognized tax benefits may significantly decrease in the next twelve months.

Other Income Tax Matters

IRS Appeals 1999-2001 (Exelon, ComEd and PECO)

1999 Sale of Fossil Generating Assets (Exelon and ComEd). Exelon, through its ComEd subsidiary, took two positions on its 1999 income tax return to defer approximately $2.8 billion of tax gain on the 1999 sale of ComEd’s fossil generating assets. Exelon deferred approximately $1.6 billion of the gain under the involuntary conversion provisions of the IRC. Exelon believes that it was economically compelled to dispose of ComEd’s fossil generating plants as a result of the Illinois Act. The proceeds from the sale of the fossil plants were properly reinvested in qualifying replacement property such that the gain was deferred over the lives of the replacement property under the involuntary conversion provisions. The remaining approximately $1.2 billion of the gain was deferred by reinvesting the proceeds from the sale in qualifying replacement property under the like-kind exchange provisions of the IRC. The like-kind exchange replacement property purchased by Exelon included interests in three municipal-owned electric generation facilities which were properly leased back to the municipalities.

Exelon received the IRS audit report for 1999 through 2001, which reflected the full disallowance of the deferral of gain associated with both the involuntary conversion position and the like-kind exchange transaction. Specifically, the IRS has asserted that ComEd was not forced to sell the fossil generating plants and the sales proceeds were therefore not received in connection with an involuntary conversion of certain ComEd property rights. Accordingly, the IRS has asserted that the gain on the sale of the assets was fully subject to tax. The IRS also asserted that the Exelon purchase and leaseback transaction is substantially similar to a leasing transaction, known as a SILO, which the IRS does not respect as the acquisition of an ownership interest in property. A SILO is a “listed transaction” that the IRS has identified as a potentially abusive tax shelter under guidance issued in 2005. Accordingly, the IRS has asserted that the sale of the fossil plants followed by the purchase and leaseback of the municipal owned generation facilities does not qualify as a like-kind exchange and the gain on the sale is fully subject to tax.

In addition to attempting to impose tax on the transactions, the IRS has asserted penalties of approximately $196 million for a substantial understatement of tax. Because Exelon believes it is unlikely that the penalty assertion will ultimately be sustained, Exelon and ComEd have not recorded a liability for penalties. However, should the IRS prevail in asserting the penalty it would result in an after-tax charge of $196 million to Exelon’s and ComEd’s results of operations.

Competitive Transition Charges (Exelon, ComEd, and PECO). Exelon contends that the Illinois Act and the Competition Act resulted in the taking of certain of ComEd’s and PECO’s assets used in their respective businesses of providing electricity services in their defined service areas. Exelon has filed refund claims with the IRS taking the position that CTCs collected during ComEd’s and PECO’s transition periods represent compensation for that taking and, accordingly, are excludible from taxable income as proceeds from an involuntary conversion. The tax basis of property acquired with the funds provided by the CTCs is reduced such that the benefits of the position are temporary in nature. The IRS has disallowed the refund claims for the 1999-2001 tax years.

Under the Illinois Act, ComEd was required to allow competitors the use of its distribution system resulting in the taking of ComEd’s assets and lost asset value (stranded costs). As compensation for the taking, ComEd was permitted to collect a portion of the stranded costs through the collection of CTCs from those customers electing to purchase electricity from providers other than ComEd. ComEd collected approximately $1.2 billion in CTCs for the years 1999-2006.

Similarly, under the Competition Act, PECO was required to allow others the use of its distribution system resulting in the taking of PECO’s assets and the stranded costs. Pennsylvania permitted PECO to collect CTCs as compensation for its stranded costs. The PAPUC determined the total amount of stranded costs that PECO was permitted to collect through the CTCs to be $5.3 billion. PECO has collected approximately $4.8 billion in CTCs for the period 2000 through June 30, 2010. PECO will continue billing CTCs through 2010.

In connection with Exelon’s discussions with the Appeals Division of the IRS (IRS Appeals) in the second quarter of 2010, the IRS proposed a settlement offer for the like-kind exchange transaction, involuntary conversion and CTC positions. Penalties asserted by the IRS are not part of the offer and remain an unresolved issue subject to further discussions with IRS Appeals. Exelon will continue to dispute the penalties and believes it is unlikely the penalties will ultimately be sustained.

Based on the status of the settlement discussions, Exelon has concluded that it has sufficient new information for the involuntary conversion and CTC positions such that a change in measurement in accordance with applicable accounting standards is required. As a result of the required re-measurement in the second quarter of 2010, Exelon recorded $65 million (after-tax) of interest expense, of which $36 million (after-tax) and $22 million (after-tax) were recorded at ComEd and PECO, respectively. ComEd also recorded a current tax expense of $70 million offset with a tax benefit recorded at Generation of $70 million. The amount recorded at Generation reflects the reduction of current taxes payable and deferred tax liabilities for the increase in tax basis of the related assets transferred from ComEd in accordance with the Contribution Agreement dated January 1, 2001. Should Exelon and IRS Appeals come to an agreement under the terms of the proposed offer and with respect to the penalties, Exelon estimates it would make a payment of approximately $235 million in 2011 for the years for which there is a resulting tax deficiency, of which $420 million would be paid by ComEd, $140 million would be received by PECO, and $10 million would be paid by Generation. These amounts are net of approximately $300 million of refunds due from the settlement of the 2001 tax method of accounting change for certain overhead costs under the SSCM as well as other agreed upon audit adjustments. Further, Exelon expects to receive an additional tax refund of approximately $300 million between 2011 and 2014, of which $360 million would be received by ComEd and $40 million would be paid by Generation.

Notwithstanding the proposal from the IRS, Exelon continues to believe that it is not possible to reach a negotiated settlement with respect to the like-kind exchange transaction. Exelon does not believe that its like-kind exchange transaction is the same as or substantially similar to a SILO and does not believe that the concession demanded by the IRS reflects the strength of Exelon’s position. Accordingly, Exelon continues to believe it is likely that the issue will be fully litigated. Given that Exelon has determined settlement is not a realistic outcome, it has assessed in accordance with applicable accounting standards whether it will prevail in litigation. While Exelon recognizes the complexity and hazards of this litigation, it believes that it is more likely than not that it will prevail in such litigation and therefore eliminated any liability for unrecognized tax benefits during the second quarter of 2009.

A fully successful IRS challenge to Exelon’s and ComEd’s like-kind exchange transaction would accelerate income tax payments and increase interest expense related to the deferred tax gain that becomes currently payable. As of June 30, 2010, Exelon’s potential tax and interest that could become currently payable in the event of a successful IRS challenge could be as much as $800 million, of which $520 million would be paid by ComEd and the remainder by Exelon. If the IRS were to prevail in litigation on the like-kind exchange position, Exelon’s results of operations could be negatively affected due to increased interest expense, as of June 30, 2010, by as much as $210 million (after-tax), of which $160 million would be recorded at ComEd and the remainder by Exelon. Litigation could take several years such that the estimated cash and interest impacts would likely change by a material amount.

Based on Exelon management’s expectations as to the ongoing potential of a settlement and litigation outcome, it is reasonably possible that the unrecognized tax benefits related to these issues may significantly change within the next 12 months. It is not possible at this time to predict the amount, if any, of such a change.

Nuclear Decommissioning (Exelon and Generation)

6 Months Ended

Jun. 30, 2010

Nuclear Decommissioning

10. Nuclear Decommissioning (Exelon and Generation)

Nuclear Decommissioning Asset Retirement Obligations

Generation has a legal obligation to decommission its nuclear power plants following the expiration of their operating licenses. The following table provides a rollforward of the nuclear decommissioning ARO reflected on Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2009 to June 30, 2010:


	Exelon and Generation
Nuclear decommissioning ARO at December 31, 2009 (a)	$	3,260
Accretion expense		96
Costs incurred to decommission retired plants		(7	)


Nuclear decommissioning ARO at June 30, 2010 (a)	$	3,349


(a)		Includes $17 million as the current portion of the ARO at June 30, 2010 and December 31, 2009, which is included in other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Nuclear Decommissioning Trust Fund Investments

Generation will pay for its respective obligations using trust funds that have been established for this purpose. At June 30, 2010 and December 31, 2009, Exelon and Generation had NDT fund investments totaling $6,498 million and $6,669 million, respectively. The following table provides unrealized gains (losses) on NDT funds for the three and six months ended June 30, 2010 and 2009:


	Exelon and Generation
	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2010			2009		2010			2009
Net unrealized gains (losses) on decommissioning trust funds —
Regulatory Agreement Units (a)	$	(318	)	$	426	$	(207	)	$	258
Net unrealized gains (losses) on decommissioning trust funds —
Non-Regulatory Agreement Units (b)		(94	)		115		(59	)		51


(a)		Gains and losses related to Generation’s NDT funds associated with Regulatory Agreement Units are included in regulatory liabilities on Exelon’s Consolidated Balance Sheets and noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.

(b)		Gains and losses related to Generation’s NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

Interest and dividends on NDT fund investments are recognized when earned and included in Other, net in Exelon and Generation’s Consolidated Statements of Operations. Interest and dividends earned on the NDT fund investments for the Regulatory Agreement Units are eliminated within Other, net in Exelon and Generation’s Consolidated Statements of Operations.

Refer to Note 3 — Regulatory Matters for information regarding regulatory liabilities at ComEd and PECO and intercompany balances between Generation, ComEd and PECO reflecting the obligation to refund the customers any decommissioning-related assets in excess of the related decommissioning obligations.

Securities Lending Program. Generation’s NDT funds participate in a securities lending program with the trustees of the funds. The program authorizes the trustees to loan securities that are assets of the trust funds to approved borrowers. Borrowers have the right to sell or re-pledge the loaned securities. The trustees require borrowers, pursuant to a security lending agreement, to deliver collateral to secure each loan. The securities are required to be collateralized by cash, U.S. Government securities or irrevocable bank letters of credit. Initial collateral levels are no less than 102% and 105% of the market value of the borrowed securities for collateral denominated in U.S. and foreign currency, respectively. Subsequent collateral levels, which are adjusted daily, must be maintained at a level no less than 100% of the market value of borrowed securities. Cash collateral received is primarily invested in a short-term collateral fund, but may also be invested in assets with maturities matching, or approximating, the duration of the loan of the related securities. The cash collateral received may not be sold or re-pledged by the trustees unless the borrower defaults. Generation bears the risk of loss with respect to its invested cash collateral. Such losses may result from a decline in fair value of specific investments or liquidity impairments resulting from current market conditions. Generation, the trustees and the borrowers have the right to terminate the lending agreement at their discretion, upon which borrowers would return securities to Generation in exchange for their cash collateral. If the short-term collateral funds do not have adequate liquidity, Generation may incur losses upon the withdrawal of amounts from the funds to repay the borrowers’ collateral. Losses recognized by Generation, whether the result of declines in fair value or liquidity impairments, have not been significant to date. Management continues to monitor the performance of the invested collateral and to work closely with the trustees to limit any potential further losses.

In 2008, Generation initiated a gradual withdrawal of the trusts’ investments in order to minimize potential losses due to liquidity constraints in the market. Currently, the weighted average maturity of the securities within the collateral pools is approximately 6 months. The fair value of securities on loan was approximately $129 million and $357 million at June 30, 2010 and December 31, 2009, respectively. The fair value of cash and non-cash collateral received for these loaned securities was $131 million at June 30, 2010 and $366 million at December 31, 2009. Generation continues to assess its participation in securities lending programs.

A portion of the income generated through the investment of cash collateral is remitted to the borrowers, and the remainder is allocated between the trust funds and the trustees in their capacity as security agents. Securities lending income allocated to the NDT funds is included in NDT fund earnings and classified as Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and was not significant during the three and six months ended June 30, 2010 and 2009.

NRC Minimum Funding Requirements. NRC regulations require that licensees of nuclear generating facilities demonstrate reasonable assurance that funds will be available in specified minimum amounts to decommission the facility at the end of its life. On March 10, 2010, Generation notified the NRC that it had remediated the December 31, 2009 underfunded position of its Byron and Braidwood NDT funds with the establishment of approximately $44 million in parent guarantees in accordance with a plan submitted by Generation to the NRC on July 31, 2009. On May 26, 2010, the NRC notified Generation that while the previously established parent guarantees complied with Generation’s remediation plan, approximately $175 million in additional parent guarantees may be required. Generation is currently in discussions with the NRC and expects the matter to be resolved during the third quarter of 2010. See Note 11 of the 2009 Form 10-K for further information on NRC minimum funding requirements.

Accounting Implications of the Regulatory Agreements with PECO and ComEd. Based on the regulatory agreement supported by the PAPUC that dictates Generation’s rights and obligations related to the shortfall or excess of trust funds necessary for decommissioning the seven former PECO nuclear units, regardless of whether the funds held in the NDT funds exceed or fall short of the total estimated decommissioning obligation, decommissioning-related activities are generally offset within Exelon’s and Generation’s Consolidated Statements of Operations. The offset of decommissioning-related activities within the Consolidated Statement of Operations results in an equal adjustment to the noncurrent payables to affiliates at Generation and an adjustment to the regulatory liabilities at Exelon. Likewise, PECO has recorded an equal noncurrent affiliate receivable from Generation and a corresponding regulatory liability. Any changes to the PECO regulatory agreements could impact Exelon’s and Generation’s ability to offset decommissioning-related activities within the Consolidated Statement of Operations, and the impact to Exelon’s and Generation’s results of operations and financial position could be material. See Note 3—Regulatory Issues for information regarding the approved Settlement permitting the NDCAC to continue after the termination of PECO’s CTC collections on December 31, 2010. The Settlement will not result in a material impact to Exelon or Generation’s future results of operations, cash flows or financial position.

See Note 11 of the 2009 Form 10-K for information regarding accounting implications of the regulatory agreement with ComEd for nuclear decommissioning.

Earnings Per Share and Equity (Exelon) [Abstract]

Nuclear Decommissioning

10. Nuclear Decommissioning (Exelon and Generation)

Nuclear Decommissioning Asset Retirement Obligations


	Exelon and Generation
Nuclear decommissioning ARO at December 31, 2009 (a)	$	3,260
Accretion expense		96
Costs incurred to decommission retired plants		(7	)


Nuclear decommissioning ARO at June 30, 2010 (a)	$	3,349


(a)		Includes $17 million as the current portion of the ARO at June 30, 2010 and December 31, 2009, which is included in other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Nuclear Decommissioning Trust Fund Investments


	Exelon and Generation
	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2010			2009		2010			2009
Net unrealized gains (losses) on decommissioning trust funds —
Regulatory Agreement Units (a)	$	(318	)	$	426	$	(207	)	$	258
Net unrealized gains (losses) on decommissioning trust funds —
Non-Regulatory Agreement Units (b)		(94	)		115		(59	)		51


(a)		Gains and losses related to Generation’s NDT funds associated with Regulatory Agreement Units are included in regulatory liabilities on Exelon’s Consolidated Balance Sheets and noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.

(b)		Gains and losses related to Generation’s NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

See Note 11 of the 2009 Form 10-K for information regarding accounting implications of the regulatory agreement with ComEd for nuclear decommissioning.

Earnings Per Share and Equity (Exelon)

6 Months Ended

Jun. 30, 2010

Earnings Per Share and Equity (Exelon)

11. Earnings Per Share and Equity (Exelon)

Earnings per Share

Diluted earnings per share is calculated by dividing net income by the weighted average number of shares of common stock outstanding, including shares to be issued upon exercise of stock options, performance share awards and restricted stock outstanding under Exelon’s long-term incentive plans considered to be common stock equivalents. The following table sets forth the components of basic and diluted earnings per share and shows the effect of these stock options, performance share awards and restricted stock on the weighted average number of shares outstanding used in calculating diluted earnings per share:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2010		2009		2010		2009

Net income	$	445	$	657	$	1,194	$	1,369


Average common shares outstanding — basic		661		659		661		659
Assumed exercise of stock options, performance share awards and restricted stock		1		2		1		2


Average common shares outstanding — diluted		662		661		662		661

The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was approximately 9 million and 6 million for the three and six months ended June 30, 2010, respectively, and 6 million and 5 million for the three and six months ended June 30, 2009, respectively.

Under share repurchase programs, 35 million shares of common stock are held as treasury stock with a cost of $2.3 billion as of June 30, 2010. In 2008, Exelon management decided to defer indefinitely any share repurchases.

Commitments and Contingencies (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Commitments and Contingencies (Exelon, Generation, ComEd and PECO) [Abstract]

Commitments and Contingencies (Exelon, Generation, ComEd and PECO)

12. Commitments and Contingencies (Exelon, Generation, ComEd and PECO)

For information regarding capital commitments at December 31, 2009, see Note 18 of the 2009 Form 10-K. All significant changes in Exelon’s, Generation’s, ComEd’s and PECO’s commitments from December 31, 2009, and all significant contingencies, are disclosed below.

Energy Commitments

Generation’s, ComEd’s and PECO’s short and long-term commitments relating to the sale and purchase of energy, capacity and transmission rights as of June 30, 2010 changed from December 31, 2009 as follows:

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Generation’s total commitments for future sales of energy to third parties increased by approximately $27 million during the six months ended June 30, 2010, reflecting increases of approximately $428 million, $123 million and $40 million related to 2011, 2012 and 2013 sales commitments, respectively, offset by the fulfillment of approximately $564 million of 2010 commitments during the six months ended June 30, 2010. The increases were primarily due to increased overall hedging activity in the normal course of business. See Note 6 - Derivative Financial Instruments for additional information regarding Generation’s hedging program.

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Generation’s total commitments for future net purchases of capacity from third parties decreased by $76 million during the six months ended June 30, 2010, reflecting increases of approximately $4 million, $4 million, $5 million, $7 million and $58 million related to 2011, 2012, 2013, 2014 and beyond net purchase commitments, respectively, due to overall hedging activity in the normal course of business. A decrease of approximately $154 million was due to the fulfillment of 2010 commitments during the six months ended June 30, 2010. See Note 6 — Derivative Financial Instruments for additional information regarding Generation’s hedging program.

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On December 17, 2009, Generation entered into a PPA with Entergy Texas, Inc. (ETI) to sell 150 MW through April 30, 2011 and 300 MW thereafter of capacity and energy from the Frontier Generating Station located in Grimes County, Texas. The approximate ten-year PPA is not included within net capacity payment commitments because it is contingent upon ETI waiving or obtaining regulatory approvals, which has not yet occurred.

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In April 2010, the ICC approved procurement contracts that enable ComEd to meet a portion of its customers’ electricity requirements for the period from June 2010 through May 2012. These contracts resulted in an increase in ComEd’s energy commitments of $195 million for the remainder of 2010, $206 million for 2011 and $15 million for 2012. See Note 3 — Regulatory Matters for additional information.

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In May 2010, ComEd entered into contracts for the procurement of RECs totaling approximately $10 million. Through June 30, 2010, $1 million had been purchased, with $9 million to be purchased by May 31, 2011. See Note 3 — Regulatory Matters for additional information.

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On May 27, 2010, PECO entered into procurement contracts in order to meet a portion of its customers’ electric supply requirements for 2011 through 2015 which increased PECO’s total purchase commitments by $1,346 million, $248 million, $56 million, $25 million and $25 million in 2011, 2012, 2013, 2014 and 2015, respectively. See Note 3 — Regulatory Matters for additional information.

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PECO’s AEC purchase commitments increased $21 million during the six months ended June 30, 2010 as a result of the solar AEC purchase agreements executed in March 2010 resulting in approximately $2 million annually over 11 years. See Note 3 — Regulatory Matters for additional information.

Fuel and Natural Gas Purchase Obligations

Generation’s and PECO’s fuel purchase obligations as of June 30, 2010 changed from December 31, 2009 as follows:

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Generation’s total fuel purchase obligations for nuclear and fossil generation decreased by approximately $658 million during the six months ended June 30, 2010, reflecting a decrease of $604 million, primarily due to the fulfillment of fuel procurement contracts.

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PECO’s total natural gas purchase obligations increased by approximately $52 million during the six months ended June 30, 2010, reflecting increases of $23 million and $29 million for the remainder of 2010 and 2011, respectively, primarily related to increased natural gas purchase commitments made in accordance with PECO’s PAPUC-approved procurement schedule.

Commercial and Construction Commitments

Exelon’s, Generation’s, ComEd’s and PECO’s commercial and construction commitments as of June 30, 2010, representing commitments potentially triggered by future events changed from December 31, 2009 as follows:

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Exelon’s letters of credit increased $3 million due to activity at Generation, ComEd and PECO as discussed below. Guarantees decreased by $37 million predominantly as a result of decreases in Generation’s guarantees as noted below, net of approximately $44 million in parent guarantees issued by Exelon as part of the remediation of the December 31, 2009 underfunded position of Generation’s Byron and Braidwood NDT funds. Guarantees decreased by $125 million for 2010, increased by $56 million for 2011 through 2012, decreased by $15 million for 2013 through 2014 and increased by $48 million for 2015 and beyond.

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Generation’s letters of credit increased by $63 million and guarantees decreased by $70 million primarily as a result of energy trading activities.

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ComEd’s letters of credit to PJM decreased by $55 million. ComEd replaced the letters of credit with $120 million of cash collateral due to favorable carrying costs for cash.

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ComEd’s PJM RTEP baseline project commitments decreased by $7 million for 2010 and increased by $5 million and $4 million for 2011 and 2012, respectively, driven by changes in estimated timing and amount of project spending.

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PECO’s outstanding letters of credit decreased by $8 million primarily due to the cancellation of a letter of credit associated with a tax credit purchase transaction that was completed in March 2010.

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PECO’s PJM RTEP baseline project commitments increased by $11 million, $11 million, $8 million and $9 million for 2010, 2011, 2012 and 2013 driven by changes in estimated timing and amount of project spending.

Other Purchase Obligations

Exelon’s, ComEd’s and PECO’s other purchase obligations as of June 30, 2010, which primarily represent commitments for services, materials and information, changed from December 31, 2009 as follows:

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Exelon’s other purchase obligations decreased by $23 million for 2010 and increased by $51 million for 2011 through 2012 and $32 million for 2013 through 2014.

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ComEd’s other purchase obligations increased by $12 million for 2010, $5 million for 2011 through 2012 and $6 million for 2013 through 2014.

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PECO’s other purchase obligations decreased by $31 million for 2010 and increased by $15 million for 2011 through 2012 and $4 million for 2013 through 2014.

Indemnifications Related to Sithe (Exelon and Generation)

On January 31, 2005, subsidiaries of Generation completed a series of transactions that resulted in Generation’s sale of its investment in Sithe. Specifically, subsidiaries of Generation consummated the acquisition of Reservoir Capital Group’s 50% interest in Sithe and subsequently sold 100% of Sithe to Dynegy, Inc. (Dynegy).

In connection with the sale, Exelon recorded liabilities related to certain indemnifications provided to Dynegy and other guarantees directly resulting from the transaction. As of June 30, 2010, Exelon’s accrued liabilities related to these indemnifications and guarantees were $5 million. The estimated maximum possible exposure to Exelon related to the guarantees provided as part of the sales transaction to Dynegy was approximately $200 million at June 30, 2010.

Indemnifications Related to Sale of Termoeléctrica del Golfo (TEG) and Termoeléctrica Peñoles (TEP) (Exelon and Generation)

On February 9, 2007, Tamuin International Inc. (TII), a wholly owned subsidiary of Generation, sold its 49.5% ownership interests in TEG and TEP to a subsidiary of AES Corporation for $95 million in cash plus certain purchase price adjustments. In connection with the transaction, Generation entered into a guarantee agreement under which Generation guarantees the timely payment of TII’s obligations to the subsidiary of AES Corporation pursuant to the terms of the purchase and sale agreement relating to the sale of TII’s ownership interests. Generation would be required to perform in the event that TII does not pay any obligation covered by the guarantee that is not otherwise subject to a dispute resolution process. Generation’s maximum obligation under the guarantee is $95 million as of June 30, 2010. The primary remaining exposures covered by this guarantee will expire in 2012.

Environmental Liabilities

General (Exelon, Generation, ComEd and PECO)

The Registrants’ operations have in the past and may in the future require substantial expenditures in order to comply with environmental laws. Additionally, under Federal and state environmental laws, the Registrants are generally liable for the costs of remediating environmental contamination of property now or formerly owned by them and of property contaminated by hazardous substances generated by them. The Registrants own or lease a number of real estate parcels, including parcels on which their operations or the operations of others may have resulted in contamination by substances that are considered hazardous under environmental laws. ComEd and PECO have identified 42 and 27 sites, respectively, where former MGP activities have or may have resulted in actual site contamination. For almost all of these sites, ComEd or PECO is one of several PRPs which may be responsible for ultimate remediation of each location. Of the 42 sites identified by ComEd, the Illinois EPA or U.S. EPA have approved the clean up of 11 sites and of the 27 sites identified by PECO, the PA DEP has approved the cleanup of 16 sites. Of the remaining sites identified by ComEd and PECO, 24 and 9 sites, respectively, are currently under some degree of active study and/or remediation. ComEd and PECO anticipate that the majority of the remediation at these sites will continue through at least 2015 and 2021, respectively. In addition, the Registrants are currently involved in a number of proceedings relating to sites where hazardous substances have been deposited and may be subject to additional proceedings in the future.

Pursuant to orders from the ICC and PAPUC, respectively, ComEd and PECO are authorized to and are currently recovering environmental costs for the remediation of former MGP facility sites from customers, for which they have recorded regulatory assets. See Note 3 — Regulatory Matters for additional information.

As of June 30, 2010 and December 31, 2009, Exelon, Generation, ComEd and PECO had accrued the following amounts for environmental liabilities:


	Total
	Environmental		Portion of Total
	Investigation and		Related to MGP
	Remediation		Investigation and
June 30, 2010	Reserve		Remediation
Exelon	$	170	$	146
Generation		15		—
ComEd		111		104
PECO		44		42


	Total
	Environmental		Portion of Total
	Investigation and		Related to MGP
	Remediation		Investigation and
December 31, 2009	Reserve		Remediation
Exelon	$	175	$	149
Generation		17		—
ComEd		113		107
PECO		45		42

The Registrants cannot predict the extent to which they will incur other significant liabilities for additional investigation and remediation costs at these or additional sites identified by environmental agencies or others, or whether such costs may be recoverable from third parties, including customers.

Section 316(b) of the Clean Water Act. In July 2004, the U.S. EPA issued the final Phase II rule implementing Section 316(b) of the Clean Water Act, which required that the cooling water intake structures at electric power plants reflect the best technology available to minimize adverse environmental impacts. The Phase II rule provided each facility with a number of compliance options and permitted site-specific variances based on a cost-benefit analysis. The requirements were intended to be implemented through state-level NPDES permit programs. All of Generation’s power generation facilities with cooling water systems are subject to the regulations. Facilities without closed-cycle recirculating systems (e.g., cooling towers) are potentially most affected. Those facilities are Clinton, Cromby, Dresden, Eddystone, Fairless Hills, Handley, Mountain Creek, Oyster Creek, Peach Bottom, Quad Cities, Salem and Schuylkill. Since promulgation of the rule, Generation has been evaluating compliance options at its affected plants and meeting interim compliance deadlines.

In a 2007 decision, the U.S. Second Circuit Court of Appeals remanded the Phase II rule back to the U.S. EPA for revisions. By its action, the court invalidated compliance measures which were supported by the utility industry because they were cost-effective and provided existing plants with needed flexibility in selecting the compliance option appropriate to its location and operations. On July 9, 2007, the U.S. EPA formally suspended the Phase II rule.

In April 2009, the U.S. Supreme Court reversed the decision of the U.S. Second Circuit Court of Appeals that had invalidated the use of a cost-benefit analysis under Section 316(b). The U.S. EPA is considering the rule on remand and will take further action consistent with the opinions of the Supreme Court and the Court of Appeals, including whether to exercise its discretion to retain or modify the cost-benefit rule as it appeared in the initial regulation. It is expected that the U.S. EPA will issue a proposed rule on remand in 2010. Until then, the state permitting agencies will continue the current practice of applying their best professional judgment to address impingement and entrainment requirements at plant cooling water intake structures. The Courts’ opinions have created significant uncertainty about the specific nature, scope and timing of the final compliance requirements.

In a draft permit issued on July 19, 2005, as part of the pending NPDES permit renewal process for Oyster Creek, the NJDEP preliminarily determined that closed-cycle cooling and environmental restoration are the only viable compliance options for Section 316(b) compliance at Oyster Creek. In light of the U.S. EPA’s suspension of the Phase II rule, on January 7, 2010, the NJDEP issued a draft NPDES permit for Oyster Creek that would require, in the exercise of its best professional judgment, the installation of cooling towers as the best technology available within seven years after the effective date of the permit. Oyster Creek will continue to operate under its current permit, issued in 1994, until the draft permit is finalized. Generation believes the regulatory process could take up to two years before a final permit is issued. Should the permit be issued in its current form, Generation estimates it would be required to have cooling towers in operation by 2019.

Generation estimates that the cost to retrofit Oyster Creek with closed cycle cooling towers would be approximately $700 million to $800 million. This cost estimate includes construction materials and labor, lost capacity and energy revenue during construction, and other ongoing incremental operating and maintenance costs. Generation believes that these additional costs would call into question the economic viability of operating Oyster Creek until the expiration of its current operating license in 2029, and Generation would close Oyster Creek if either the final Section 316(b) regulations or NJDEP requirements have performance standards that require the installation of cooling towers. Closure of Oyster Creek could result in reliability issues associated with the transmission system. Generation believes the period allowed for compliance will be sufficient to address any transmission reliability issues before operations at Oyster Creek are shut down. If PJM requires the plant to operate under a “reliability-must-run” order, Generation would be allowed full recovery of its costs to operate until the transmission issues are resolved.

In June 2001, the NJDEP issued a renewed NPDES permit for Salem, allowing for the continued operation of Salem with its existing cooling water system. NJDEP advised PSEG in July 2004 that it strongly recommended reducing cooling water intake flow commensurate with closed-cycle cooling as a compliance option for Salem. PSEG submitted an application for a renewal of the permit on February 1, 2006. In the permit renewal application, PSEG analyzed closed-cycle cooling and other options and demonstrated that the continuation of the Estuary Enhancement Program, an extensive environmental restoration program at Salem, is the best technology to meet the Section 316(b) requirements. PSEG continues to operate Salem under the approved June 2001 NPDES permit while the NPDES permit renewal application is being reviewed. If the final permit or Section 316(b) regulations ultimately requires the retrofitting of Salem’s cooling water intake structure to reduce cooling water intake flow commensurate with closed-cycle cooling, Exelon’s and Generation’s share of the total cost of the retrofit and any resulting interim replacement power would likely be in excess of $500 million and could result in increased depreciation expense related to the retrofit investment.

Generation is contesting the requirement to install cooling towers at Oyster Creek through the administrative appeal process and is optimistic that any final regulations or permits will not require closed-cycle cooling at Oyster Creek or Salem. In addition, the economic viability of Generation’s other power generation facilities without closed-cycle cooling water systems will be called into question by any requirement to construct cooling towers. Given the uncertainties associated with these proceedings and the time required for their resolution, Generation cannot predict the eventual outcome of the proceedings or estimate the effect that compliance with any resulting Section 316(b) or interim state requirements will have on the operation of its generating facilities and its future results of operations, cash flows and financial position.

Nuclear Generating Station Groundwater. In 2005 and 2006, the Illinois EPA issued NOVs to Generation alleging violations of state groundwater standards at the Braidwood, Dresden and Byron generating stations related to tritium leaks at the plants. Tritium is a weak radioactive isotope of hydrogen that is produced and released at all nuclear sites and also is released naturally through the interaction of sunlight and water molecules. In addition, the Illinois Attorney General and the State’s Attorney for the counties in which the plants are located filed civil enforcement lawsuits against Generation. On March 11, 2010, Generation agreed to a settlement of all pending actions related to the leaks. Under the terms of the settlement, Generation paid approximately $1.2 million in civil penalties and funds for supplemental environmental projects in the communities where the plants are located.

As part of normal operations, Generation and the operators of Generation’s co-owned facilities perform ongoing environmental monitoring at all nuclear generating stations. In 2009 and 2010, tritium was detected at the Oyster Creek, LaSalle and Salem generating stations. Plans have been implemented to ensure that tritium detected at the sites does not pose a threat to site employees, the public or the environment. No NOVs have been issued in connection with any of these matters. At this time Exelon cannot estimate the costs of possible remediation efforts for these matters.

Cotter Corporation. The U.S. EPA has advised Cotter Corporation (Cotter), a former ComEd subsidiary, that it is potentially liable in connection with radiological contamination at a site known as the West Lake Landfill in Missouri. On February 18, 2000, ComEd sold Cotter to an unaffiliated third party. As part of the sale, ComEd agreed to indemnify Cotter for any liability arising in connection with the West Lake Landfill. In connection with Exelon’s 2001 corporate restructuring, this responsibility to indemnify Cotter was transferred to Generation. Cotter is alleged to have disposed of approximately 39,000 tons of soils mixed with 8,700 tons of leached barium sulfate at the site. On May 29, 2008, the U.S. EPA issued a Record of Decision approving the remediation option submitted by Cotter and the two other PRPs that required additional landfill cover. The current estimated cost of the anticipated landfill cover remediation for the site is $37 million, which will be allocated among all PRPs. Generation has accrued what it believes to be an adequate amount to cover its anticipated share of such liability. By letter dated January 11, 2010, the U.S. EPA requested that the PRPs perform a supplemental feasibility study for a remediation alternative that would involve excavation of the radiological contamination. An excavation remedy would be significantly more expensive than the previously selected additional cover remedy. Generation cannot determine at this time whether the alternative remedy will be required, and if it is, Generation’s share of the cost for such alternative remedy.

Air. On July 11, 2008, the U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit Court) vacated the CAIR, which had been promulgated by the U.S. EPA to reduce power plant emissions of SO₂ and NO_x. The D.C. Circuit Court later remanded the CAIR to the U.S. EPA, without invalidating the entire rulemaking, so that the U.S. EPA could remedy “CAIR’s flaws” in accordance with the D.C. Circuit Court’s July 11, 2008 opinion. This decision allows the CAIR to remain in effect until it is replaced by a rule consistent with the July 11 opinion. On July 6, 2010, the U.S. EPA published the proposed CATR as the replacement to the CAIR. The first phase of the NO_x and SO₂ emissions reductions under CATR will commence in 2012, with further reductions of SO₂ emissions proposed to become effective in 2014. These emissions limits will be further reduced as the U.S. EPA finalizes more restrictive NAAQS for ozone and fine particulate matter in the 2010 — 2011 timeframe.

As of June 30, 2010, Generation had $71 million of emission allowances carried in inventory at the lower of weighted average cost or market. This amount includes SO₂ allowances allocated under the Title IV Acid Rain Program (ARP), of which approximately $58 million represents allowances that are not expected to be used by Generation’s fossil-fuel power plants and that have not been sold. Generation is evaluating the impact the proposed CATR regulations may have on the market value of its ARP SO₂ allowances. The proposed CATR regulations would restrict entirely the use of ARP SO₂ allowances. If implemented as proposed, and based on initial allowance market prices after the publication of CATR, the adoption of the CATR provisions could significantly reduce the market value of these allowances as they would only be available for use under the Title IV ARP program. To the extent the weighted average cost of the ARP SO₂ allowances held exceeds the market value in future periods, an impairment of some or all of the $58 million may be necessary.

Additionally, as of June 30, 2010, Exelon has a $615 million net investment in long-term direct financing leases of coal-fired plants in Georgia and Texas extending through 2028-2032. While Exelon currently estimates the value of these plants at the end of the lease term, before taking into account impacts of the proposed CATR regulations, will be substantially in excess of the recorded residual lease values, Exelon is unable to determine the ultimate impact the proposed regulations may have on the end-of-lease term values of these assets.

In March 2005, the U.S. EPA finalized the CAMR, which was a national program to cap mercury emissions from fossil-fired generating units starting in 2010, with a second reduction in the mercury emission cap level scheduled for 2018. The D.C. Circuit Court later vacated the CAMR on the basis that the U.S. EPA had failed to properly de-list mercury as a HAP under Section 112(c)(1) of the Clean Air Act. The result of this decision is that mercury emissions from electric generating stations are subject to the more stringent requirements of maximum achievable control technology applicable to hazardous air pollutants. On February 23, 2009, the U.S. Supreme Court declined to review the D.C. Circuit Court’s CAMR decision. The U.S. EPA is now expected to propose a new rulemaking, likely in 2011, to address HAP emissions from electric generation power plants. The nature and extent of future regulatory controls on HAP emissions at electric generation power plants will not be determined until the Federal regulations are finalized by the U.S. EPA.

The U.S. EPA has announced that it will complete a review of the national ambient air quality standards by the end of 2011 for ozone (nitrogen oxide and volatile organic chemicals), particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead. This review could result in more stringent emissions limits on fossil-fired electric generating stations.

Notices and Finding of Violations Related to Electric Generation Stations. On August 6, 2007, ComEd received an NOV, addressed to it and Midwest Generation, LLC (Midwest Generation) from the U.S. EPA, alleging that ComEd and Midwest Generation have violated and are continuing to violate several provisions of the Clean Air Act as a result of the modification and/or operation of six electric generation stations located in northern Illinois that have been owned and operated by Midwest Generation since 1999. The U.S. EPA requested information related to the stations in 2003, and ComEd has been cooperating with the U.S. EPA since then. The NOV states that the U.S. EPA may issue an order requiring compliance with the relevant Clean Air Act provisions and may seek injunctive relief and/or civil penalties, all pursuant to the U.S. EPA’s enforcement authority under the Clean Air Act.

The generating stations that are the subject of the NOV are currently owned and operated by Midwest Generation, which purchased the stations in December 1999 from ComEd. Under the terms of the sale agreement, Midwest Generation and its affiliate, Edison Mission Energy (EME), assumed responsibility for environmental liabilities associated with the ownership, occupancy, use and operation of the stations, including responsibility for compliance of the stations with environmental laws before the purchase of the stations by Midwest Generation. Midwest Generation and EME additionally agreed to indemnify and hold ComEd and its affiliates harmless from claims, fines, penalties, liabilities and expenses arising from third party claims against ComEd resulting from or arising out of the environmental liabilities assumed by Midwest Generation and EME under the terms of the agreement governing the sale.

In August 2009, the U.S. Department of Justice and the Illinois Attorney General filed a complaint against Midwest Generation with the U.S. District Court for the Northern District of Illinois initiating enforcement proceedings with respect to the alleged Clean Air Act violations set forth in the NOV. Neither ComEd nor Exelon were named as a defendant in this original complaint. In March 2010, the District Court granted Midwest Generation’s partial motion to dismiss all but one of the claims against Midwest Generation. The court held that Midwest Generation cannot be liable for any alleged violations relating to construction that occurred prior to Midwest Generation’s ownership of the stations. In May 2010, the government plaintiffs filed an amended complaint substantially similar to the original complaint, and added ComEd and EME as defendants. The amended complaint seeks injunctive relief and civil penalties against all defendants, although not all of the claims specifically pertain to ComEd.

In connection with Exelon’s 2001 corporate restructuring, Generation assumed ComEd’s rights and obligations with respect to its former generation business. Exelon, Generation and ComEd are unable to predict the ultimate resolution of the claims alleged in the amended complaint, the costs that might be incurred or the amount of indemnity that may be available from Midwest Generation and EME; however, Exelon, Generation and ComEd have concluded that, while a loss may be reasonably possible, they believe the likelihood of loss is not probable. Therefore, no reserve has been established. Further, Generation believes that it would be reimbursed for any losses under the terms of the indemnification agreement, subject to the credit worthiness of Midwest Generation and EME. Exelon, Generation and ComEd cannot predict an estimated amount or range of possible loss.

On January 14, 2009, Generation received an NOV addressed to it, the other owners of Keystone Generating Station (Keystone) and Reliant Energy Northeast Management Company (the operator of Keystone) from the U.S. EPA, alleging past and continuing violations of several provisions of the Clean Air Act as a result of the modification and/or operation of Keystone, as well as two other stations currently owned and operated by Reliant Energy in which Generation has no ownership interest. Generation has been cooperating with the U.S. EPA since the time of requests for information in 2000, 2001 and 2007. The NOV states that the U.S. EPA may issue an order requiring compliance with the relevant Clean Air Act provisions and may seek injunctive relief and/or civil penalties, all pursuant to the U.S. EPA’s enforcement authority under the Clean Air Act. At this time, Exelon and Generation are unable to predict the ultimate resolution of the claims alleged in the NOV or the costs that might be incurred by Generation; however, Exelon and Generation have concluded that a loss is not probable or estimable and, accordingly, have not recorded a reserve for the NOV.

On April 16, 2009, the U.S. EPA issued an NOV to ComEd and Dominion Resources Services, Inc. (Dominion) alleging past and continuing violations of several provisions of the Clean Air Act as a result of the modification and/or operation of Kincaid electric generating station located in Illinois and State Line electric generating station located in Indiana. Kincaid was sold by ComEd in 1998, and State Line was sold by Commonwealth Edison of Indiana, a wholly owned subsidiary of ComEd, in 1997. Both stations are currently owned and operated by Dominion. The U.S. EPA requested information related to the stations in 2009, and ComEd has been cooperating with the U.S. EPA since the time of that request. The NOV states that the U.S. EPA may issue an order requiring compliance with the relevant Clean Air Act provisions and may seek injunctive relief and/or civil penalties, all pursuant to the U.S. EPA’s enforcement authority under the Clean Air Act.

Under the terms of the sales agreements for the Kincaid and State Line stations, each party agreed to indemnify the other for certain environmental activities, events, conditions or occurrences arising before and after the purchase of the stations; however, Exelon, Generation, and ComEd are unable at this time to determine how those provisions may apply to any liability or cost that may eventually arise out of the NOV or any resulting enforcement action.

In connection with Exelon’s 2001 corporate restructuring, Generation assumed ComEd’s rights and obligations related to ComEd’s former generation business, which would include any responsibility under the indemnification provisions contained in the sale agreements related to Kincaid and State Line stations. At this time, Exelon, Generation and ComEd are unable to predict the ultimate resolution of the claims alleged in the NOV or the costs that might be incurred by Generation or ComEd; however, Exelon, Generation and ComEd have concluded that a loss is not probable and, accordingly, have not recorded a reserve for the NOV.

Climate Change Regulation. Exelon is subject to climate change regulation or legislation at the international, Federal, regional and state levels.

International Climate Change Regulation. At the international level, the United States is currently not a party to the Kyoto Protocol, which is a protocol to the United Nations Framework Convention on Climate Change (UNFCCC) and became effective for signatories on February 16, 2005. The United Nations’ Kyoto Protocol process generally requires developed countries to cap GHG emissions at certain levels during the 2008-2012 time period. At the conclusion of the December 2007 United Nations Climate Change Conference in Bali, Indonesia, the Bali Action Plan was adopted, which identifies a work group, process and timeline for the consideration of possible post-2012 international actions to further address climate change. In December 2009, the United States agreed to the non-binding Copenhagen Accord at the conclusion of the 15th Conference of the Parties under the UNFCCC. Under the Copenhagen Accord, the United States agreed to undertake a number of voluntary measures, including the establishment of a goal to reduce GHG emissions and contributions toward a fund to assist developing nations to address their GHG emissions. The next Conference of the Parties is scheduled for Mexico in late 2010.

Federal Climate Change Legislation and Regulation. Various stakeholders, including Exelon, legislators and regulators, shareholders and non-governmental organizations, as well as other companies in many business sectors are considering ways to address the climate change issue. Mandatory programs to reduce GHG emissions are likely to evolve in the future. If these programs become effective, Exelon may incur costs either to further limit or offset the GHG emissions from its operations or procure emission allowances or credits.

Numerous bills have been introduced in Congress that address climate change from different perspectives, including direct regulation of GHG emissions and the establishment of Federal Renewable Portfolio Standards. Exelon supports the enactment, through Federal legislation, of a cap-and-trade program for GHG emissions that is mandatory, economy-wide and designed in a way to limit potential harm to the economy and protect consumers. Exelon believes that any mechanism for allocation of GHG emission allowances should include significant free grants of allowances to electric (and potentially gas) distribution companies to help offset the cost impact of GHG regulation to the end-use consumer. Over the last few years, Exelon has worked with other businesses and environmental organizations that participate in the United States Climate Action Partnership to support the development of an integrated package of recommendations for the Federal government to address the climate change issue through Federal legislation, including aggressive emission reduction targets for total U.S. emissions and robust cost containment measures to ensure that program costs are reasonable.

Federal climate change legislation is currently under consideration in the U.S. Congress. H.R. 2454, “The American Clean Energy and Security Act of 2009,” which Exelon supported, was approved by the U.S. House of Representatives on June 26, 2009 and would affect electric generation and electric and natural gas distribution companies. A key provision of H.R. 2454 is the establishment of mandatory, economy-wide GHG reduction targets and goals via a Federal emissions cap-and-trade program. The program would begin in 2012 and calls for a 3% reduction below 2005 levels in 2012, with the reduction requirement increasing to 17% below 2005 levels by 2020 and ultimately 83% below 2005 levels by 2050. The legislation also contains several energy efficiency and clean energy requirements. Of particular note for electric retail supply companies, there is a proposed requirement that 20% of electricity sold by retail suppliers be met by energy efficiency and renewable energy by 2020. The requirement begins to phase-in starting in 2012 at a 6% level and escalates every two years until it reaches 20% in 2020. On September 30, 2009, S. 1733, the Clean Energy Jobs and American Power Act, was introduced in the U.S. Senate. S.1733 sets forth a cap-and-trade program and contains other provisions to regulate GHGs that are similar to those contained in H.R. 2454, but does not yet provide the specific details regarding the allocation of allowances. It is uncertain when the Senate will take up consideration of S. 1733, or an alternative bill.

In 2007, the U.S. Supreme Court ruled that GHG emissions are pollutants subject to regulation under the new motor vehicle provisions of the Clean Air Act. In response to the decision, on July 11, 2008, the U.S. EPA issued an Advance Notice of Proposed Rulemaking to solicit public comments on legal and regulatory analyses and policy alternatives regarding GHG effects and regulation under the Clean Air Act. On December 7, 2009, the U.S. EPA issued an endangerment finding under Section 202 of the Clean Air Act regarding GHGs from new motor vehicles and on April 1, 2010 issued final regulations limiting GHG emissions from cars and light trucks effective on January 2, 2011. While such regulations do not specifically address stationary sources, such as a generating plant, it is the U.S. EPA’s position that the regulation of GHGs under the mobile source provisions of the Clean Air Act will trigger permitting requirements under the Prevention of Significant Deterioration and Title V operating permit sections of the Clean Air Act for new and modified stationary sources effective January 2, 2011. Therefore, on May 13, 2010, the U.S. EPA issued final regulations relating to these provisions of the Clean Air Act for major stationary sources of GHG emissions that apply to new sources that emit greater than 100,000 tons per year, on a CO₂ equivalent basis, and to modifications to existing sources that result in emissions increases greater than 75,000 tons per year on a CO₂ equivalent basis. These thresholds are effective January 2, 2011, apply for six years and will be reviewed by the U.S. EPA for future applicability thereafter. Under the regulations, new and modified major stationary sources could be required to install best available control technology, to be determined on a case-by-case basis.

The issue of GHG regulation of stationary sources will likely be addressed either under the existing provisions of the Clean Air Act by U.S. EPA regulation, or by new and comprehensive Federal legislation. The Obama administration and the U.S. EPA have stated a preference for addressing the issue through Federal legislation. The extent to which GHG emissions will be regulated is currently unknown; however, potential regulation of GHG emissions from stationary sources could cause Exelon to incur material costs of compliance.

Regional and State Climate Change Legislation and Regulation. At a regional level, on November 15, 2007, six Midwest state Governors (Illinois, Iowa, Kansas, Michigan, Minnesota and Wisconsin) signed the Midwestern Greenhouse Gas Accord. Under that Accord, an inter-state work group was formed to establish a Midwestern GHG Reduction Program that will: (1) establish GHG reduction targets and timeframes consistent with member state targets; (2) develop a market-based and multi-sector cap-and-trade program to help achieve GHG reductions; and (3) develop other mechanisms and policies to assist in meeting GHG reduction targets (e.g. a low carbon fuel standard). In May 2010, an advisory group appointed by the Governors issued recommendations, which are now under review by the Governors.

At the state level, the PCCA was signed into law in July 2008. The PCCA requires, among other things, that a Climate Change Advisory Committee be formed, that a report on the potential impact of climate change in Pennsylvania be developed, that the PA DEP develop a GHG inventory for Pennsylvania, that a voluntary GHG registry be identified, and that the PA DEP, in consultation with the Climate Change Advisory Committee, develop a Climate Change Action Plan for Pennsylvania to be reviewed with the Pennsylvania General Assembly. The Climate Change Advisory Committee issued its recommendations for an Action Plan on October 9, 2009 and they are currently being considered by the Pennsylvania legislature.

At this time, Exelon is unable to estimate the potential impacts of any future mandatory GHG legal or regulatory requirements on its businesses.

Litigation Matters

Except to the extent noted below, the circumstances set forth in Note 18 of the 2009 Form 10-K describe, in all material respects, the current status of litigation matters. The following is an update to that discussion.

Exelon and Generation

Asbestos Personal Injury Claims. Generation maintains a reserve for claims associated with asbestos-related personal injury actions in certain facilities that are currently owned by Generation or were previously owned by ComEd and PECO. The reserve is recorded on an undiscounted basis and excludes the estimated legal costs associated with handling these matters, which could be material. In the second quarter of 2008, Generation revised the period through which it estimates that claims will be presented from 2030 to 2050.

At June 30, 2010 and December 31, 2009, Generation had reserved approximately $53 million and $49 million, respectively, in total for asbestos-related bodily injury claims. As of June 30, 2010, approximately $15 million of this amount related to 171 open claims presented to Generation, while the remaining $38 million of the reserve is for estimated future asbestos-related bodily injury claims anticipated to arise through 2050 based on actuarial assumptions and analyses, which are updated on an annual basis. On a quarterly basis, Generation monitors actual experience against the number of forecasted claims to be received and expected claim payments and evaluates whether an adjustment to the reserve is necessary. During the three months ended June 30, 2010, Generation increased its reserve by approximately $4 million, primarily due to an increase in forecasted claims. Updates to this reserve in 2009 did not result in material adjustments.

Exelon

Pension Claims. On February 22, 2010, the U.S. Supreme Court declined to hear an appeal of the July 2, 2009 decision of the U.S. Court of Appeals for the Seventh Circuit affirming dismissal of claims that the calculation of lump sum benefits earned under the Exelon Corporation Cash Balance Pension Plan (Plan) did not comply with ERISA. The Plan’s motion for summary judgment on remaining claims regarding the Plan’s calculation of lump sum benefits earned under a prior, traditional pension formula remains pending before the U.S. District Court for the Northern District of Illinois.

Exelon, Generation, ComEd and PECO

General. The Registrants are involved in various other litigation matters that are being defended and handled in the ordinary course of business. The Registrants maintain accruals for such costs that are probable of being incurred and subject to reasonable estimation. The Registrants will record a receivable if they expect to recover costs for these contingencies. The ultimate outcomes of such matters, as well as the matters discussed above, are uncertain and may have a material adverse impact on the Registrants’ results of operations, cash flows or financial positions.

Income Taxes

See Note 9 — Income Taxes for information regarding the Registrants’ income tax refund claims and certain tax positions, including the 1999 sale of fossil generating assets.

Supplemental Financial Information (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Supplemental Financial Information (Exelon, Generation, ComEd and PECO) [Abstract]

Supplemental Financial Information (Exelon, Generation, ComEd and PECO)

13. Supplemental Financial Information (Exelon, Generation, ComEd and PECO)

Supplemental Statement of Operations Information

The following tables provide additional information about the Registrants’ Consolidated Statements of Operations for the three and six months ended June 30, 2010 and 2009:


Three Months Ended June 30, 2010	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	279	$	115	$	117	$	42
Regulatory assets(a)		240		—		14		226
Nuclear fuel(b)		168		168		—		—
Asset retirement obligation accretion(c)		50		49		—		—


Total depreciation, amortization and accretion	$	737	$	332	$	131	$	268


Six Months Ended June 30, 2010	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	558	$	223	$	234	$	85
Regulatory assets(a)		475		—		27		448
Nuclear fuel(b)		323		323		—		—
Asset retirement obligation accretion(c)		99		99		—		—


Total depreciation, amortization and accretion	$	1,455	$	645	$	261	$	533


Three Months Ended June 30, 2009	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	237	$	72	$	112	$	40
Regulatory assets(a)		202		—		12		190
Nuclear fuel(b)		139		139		—		—
Asset retirement obligation accretion(c)		53		53		—		—


Total depreciation, amortization and accretion	$	631	$	264	$	124	$	230


Six Months Ended June 30, 2009	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	475	$	149	$	221	$	80
Regulatory assets(a)		400		—		25		375
Nuclear fuel(b)		272		272		—		—
Asset retirement obligation accretion(c)		106		105		—		—


Total depreciation, amortization and accretion	$	1,253	$	526	$	246	$	455


(a)		For PECO, primarily reflects CTC amortization.

(b)		Included in fuel expense on the Registrants’ Consolidated Statements of Operations.

(c)		Included in operating and maintenance expense on the Registrants’ Consolidated Statements of Operations.


Three Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units (a)	$	49		$	49		$	—	$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units (a)		14			14			—		—
Net unrealized losses on decommissioning trust funds —
Regulatory Agreement Units		(318	)		(318	)		—		—
Net unrealized losses on decommissioning trust funds —
Non-Regulatory Agreement Units		(94	)		(94	)		—		—
Regulatory offset to decommissioning trust fund-related activities(b)		215			215			—		—

Total decommissioning-related activities		(134	)		(134	)		—		—

Net direct financing lease income		7			—			—		—
Interest income related to uncertain income tax positions		—			—			2		—
Other		5			1			6		(1	)


Other, net	$	(122	)	$	(133	)	$	8	$	(1	)


Six Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units(a)	$	98		$	98		$	—	$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units(a)		26			26			—		—
Net unrealized losses on decommissioning trust funds —
Regulatory Agreement Units		(207	)		(207	)		—		—
Net unrealized losses on decommissioning trust funds —
Non-Regulatory Agreement Units		(59	)		(59	)		—		—
Regulatory offset to decommissioning trust fund-related activities(b)		87			87			—		—

Total decommissioning-related activities		(55	)		(55	)		—		—

Net direct financing lease income		13			—			—		—
Interest income related to uncertain income tax positions		—			—			2		—
Other		13			1			9		4


Other, net	$	(29	)	$	(54	)	$	11	$	4


(a)		Includes investment income and realized gains and losses on sales of investments of the trust funds.

(b)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of net realized income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.


Three Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units (a)	$	10		$	10		$	—		$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units (a)		10			10			—			—
Net unrealized gains on decommissioning trust funds —
Regulatory Agreement Units		426			426			—			—
Net unrealized gains on decommissioning trust funds —
Non-Regulatory Agreement Units		115			115			—			—
Regulatory offset to decommissioning trust fund-related activities (b)		(349	)		(349	)		—			—

Total decommissioning-related activities		212			212			—			—

Net direct financing lease income		7			—			—			—
Interest income related to uncertain income tax positions (c)		38			—			59			2
Other-than-temporary impairment to Rabbi trust investments (d)		(7	)		—			(7	)		—
Other		7			3			3			1


Other, net	$	257		$	215		$	55		$	3


Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units(a)	$	28		$	28		$	—		$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units(a)		18			18			—			—
Net unrealized gains on decommissioning trust funds —
Regulatory Agreement Units		258			258			—			—
Net unrealized gains on decommissioning trust funds —
Non-Regulatory Agreement Units		51			51			—			—
Regulatory offset to decommissioning trust fund-related activities(b)		(234	)		(234	)		—			—

Total decommissioning-related activities		121			121			—			—

Investment income		1			—			—			1
Net direct financing lease income		13			—			—			—
Interest income related to uncertain income tax positions (c)		77			4			87			3
Other-than-temporary impairment to Rabbi trust investments (d)		(7	)		—			(7	)		—
Other		14			8			7			2


Other, net	$	219		$	133		$	87		$	6


(a)		Includes investment income and realized gains and losses on sales of investments of the trust funds.

(b)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of net realized income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.

(c)		Primarily includes interest income at Generation and ComEd related to the February 2009 Illinois Supreme Court decision regarding refund claims for Illinois investment tax credits, which was reversed in the third quarter of 2009. See Note 10 of the 2009 Form 10-K for additional information.

(d)		ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009.

Supplemental Cash Flow Information

The following tables provide additional information regarding the Registrants’ Consolidated Statements of Cash Flows for the six months ended June 30, 2010 and 2009:


Six Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other non-cash operating activities:
Pension and non-pension postretirement benefits costs	$	288		$	134		$	106	$	24
Provision for uncollectible accounts		38			1			16		21
Stock-based compensation costs		27			—			—		—
Other decommissioning-related activity (a)		31			31			—		—
Energy-related options (b)		(36	)		(36	)		—		—


Six Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO
Amortization of regulatory asset related to debt costs		12			—			11			2
Accrual for Illinois utility distribution tax refund (c)		(25	)		—			(25	)		—
Under-recovered uncollectible accounts, net (d)		(49	)		—			(49	)		—
Other		(8	)		3			1			(3	)


Total other non-cash operating activities	$	278		$	133		$	60		$	44


Changes in other assets and liabilities:
Under/over-recovered energy and transmission costs		60			—			44			16
Other current assets		(172	)		(57	)		10			(127	)(e)
Other noncurrent assets and liabilities		103			23			41			37


Total changes in other assets and liabilities	$	(9	)	$	(34	)	$	95		$	(74	)


Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other non-cash operating activities:
Pension and non-pension postretirement benefits costs	$	263		$	120		$	96		$	23
Loss in equity method investments		14			1			—			12
Provision for uncollectible accounts		65			3			25			38
Stock-based compensation costs		42			—			—			—
Other decommissioning-related activity (a)		(43	)		(43	)		—			—
Energy-related options (b)		31			31			—			—
Amortization of regulatory asset related to debt costs		14			—			12			2
Amortization of the regulatory liability related to the PURTA tax settlement (f)		(2	)		—			—			(2	)
Other-than-temporary impairment to Rabbi trust investments (g)		7			—			7			—
Other		20			1			19			10


Total other non-cash operating activities	$	411		$	113		$	159		$	83


Changes in other assets and liabilities:
Under/over-recovered energy and transmission costs		58			—			47			11
Other current assets		(150	)		(5	)		1			(137	)(e)
Other noncurrent assets and liabilities		(105	)		(16	)		(82	)		(2	)


Total changes in other assets and liabilities	$	(197	)	$	(21	)	$	(34	)	$	(128	)


(a)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.

(b)		Reclassification of energy-related option premiums to realized at settlement of contracts recorded in results of operations due to the settlement of the underlying transaction.

(c)		During the second quarter, ComEd recorded a reduction of $25 million to taxes other than income to reflect management’s estimate of future refunds for the 2008 and 2009 tax years associated with Illinois’ utility distribution tax based on an analysis of past refunds and interpretations of the Illinois Public Utility Act. Historically, ComEd has recorded refunds of the Illinois utility distribution tax when received. ComEd believes it now has sufficient, reliable evidence to record and support an estimated receivable associated with the anticipated refund for the 2008 and 2009 tax years.

(d)		Includes $70 million of under-recovered uncollectible accounts expense from 2008 and 2009 recorded in the first quarter of 2010 as well as subsequent adjustments to and amortization of the associated regulatory asset. ComEd is recovering these costs through a rider mechanism authorized by the ICC. See Note 3 — Regulatory Matters for additional information regarding the Illinois legislation for recovery of uncollectible accounts.

(e)		Relates primarily to prepaid utility taxes.

(f)		In March 2007, PECO prevailed in a Pennsylvania Supreme Court case in which PECO had contested the assessment of PURTA taxes applicable to 1997. As a result, PECO received approximately $38 million of real estate taxes previously remitted. This refund was recorded as a regulatory liability. PECO began amortizing this liability and refunding customers in January 2008. The regulatory liability associated with the PURTA settlement was fully amortized in January 2009.

(g)		ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009.

Supplemental Balance Sheet Information

The following tables provide information regarding accumulated depreciation and the allowance for uncollectible accounts as of June 30, 2010 and December 31, 2009:


June 30, 2010	Exelon			Generation			ComEd		PECO
Property, plant and equipment:
Accumulated depreciation	$	9,341	(a)	$	4,395	(a)	$	2,240	$	2,488
Accounts receivable:
Allowance for uncollectible accounts		228			31			83		114


December 31, 2009	Exelon			Generation			ComEd		PECO
Property, plant and equipment:
Accumulated depreciation	$	9,023	(b)	$	4,214	(b)	$	2,129	$	2,442
Accounts receivable:
Allowance for uncollectible accounts		225			31			77		117


(a)		Includes accumulated amortization of nuclear fuel in the reactor core of $1,384 million.

(b)		Includes accumulated amortization of nuclear fuel in the reactor core of $1,383 million.

The following tables provide information about accumulated OCI (loss) recorded (after tax) within the consolidated Balance Sheets of the Registrants as of June 30, 2010 and December 31, 2009:


June 30, 2010	Exelon			Generation		ComEd			PECO
Accumulated other comprehensive income (loss)
Net unrealized gain (loss) on cash flow hedges	$	525		$	1,163	$	(4	)	$	—
Pension and non-pension postretirement benefit plans		(2,603	)		—		—			—


Total accumulated other comprehensive income (loss)	$	(2,078	)	$	1,163	$	(4	)	$	—


December 31, 2009	Exelon			Generation		ComEd		PECO
Accumulated other comprehensive income (loss)
Net unrealized gain on cash flow hedges	$	551		$	1,157	$	—	$	1
Pension and non-pension postretirement benefit plans		(2,640	)		—		—		—


Total accumulated other comprehensive income (loss)	$	(2,089	)	$	1,157	$	—	$	1

Segment Information (Exelon, Generation, ComEd and PECO)

6 Months Ended

Jun. 30, 2010

Segment Information (Exelon, Generation, ComEd and PECO) [Abstract]

Segment Information (Exelon, Generation, ComEd and PECO)

14. Segment Information (Exelon, Generation, ComEd and PECO)

During the first quarter of 2010, Exelon and Generation concluded that Generation no longer operates as a single reportable segment, primarily due to a change in the financial information regularly evaluated by the chief operating decision maker (CODM) in determining resource allocation and assessing performance. Certain regional results of Generation’s power marketing activities are now being provided to the CODM and in other public disclosures. As a result, beginning in the first quarter of 2010, Generation has three reportable segments consisting of Mid-Atlantic, Midwest and South. Consequently, Exelon has five reportable segments consisting of Mid-Atlantic, Midwest, South, ComEd and PECO. Prior period presentation has been adjusted for comparative purposes.

Mid-Atlantic represents Generation’s operations primarily in Pennsylvania, New Jersey and Maryland; Midwest includes operations in Illinois and Indiana; and South includes operations primarily in Texas, Georgia and Oklahoma. Exelon and Generation evaluate the performance of Generation’s power marketing activities in Mid-Atlantic, Midwest and South based on revenue net of purchased power and fuel expense. Generation believes that revenue net of purchased power and fuel expense is a useful measurement of operational performance. Revenue net of purchased power and fuel expense is not a presentation defined under GAAP and may not be comparable to other companies’ presentations or deemed more useful than the GAAP information provided elsewhere in this report. Generation’s operating revenues include all sales to third parties and affiliated sales to ComEd and PECO. Purchased power costs include all costs associated with the procurement of electricity including capacity, energy and fuel costs associated with tolling agreements. Fuel expense includes the fuel costs for internally generated energy. Generation’s retail gas, proprietary trading, other revenue and mark-to-market activities are not allocated to a region. Exelon and Generation do not use a measure of total assets in making decisions regarding allocating resources to or assessing the performance of these reportable segments.

ComEd and PECO each represent a single reportable segment; as such, no separate segment information is provided for these Registrants. PECO has two operating segments, electric and gas delivery, which are aggregated into one reportable segment primarily due to their similar economic characteristics and the regulatory environments in which they operate. Exelon evaluates the performance of ComEd and PECO based on net income.

An analysis and reconciliation of the Registrants’ reportable segment information to the respective information in the consolidated financial statements for the three and six months ended June 30, 2010 and 2009 is as follows:

Three Months Ended June 30, 2010 and 2009


										Intersegment
	Generation(a)		ComEd		PECO		Other			Eliminations			Exelon
Total revenues(b):
2010	$	2,353	$	1,499	$	1,269	$	177		$	(900	)	$	4,398
2009		2,378		1,389		1,204		207			(1,037	)		4,141
Intersegment revenues(c):
2010	$	725	$	—	$	1	$	177		$	(900	)	$	3
2009		833		—		2		207			(1,036	)		6
Net income (loss):
2010	$	382	$	9	$	75	$	(21	)	$	—		$	445
2009		512		116		71		(35	)		(7	)		657
Total assets:
June 30, 2010	$	22,499	$	20,870	$	9,071	$	5,384		$	(8,651	)	$	49,173
December 31, 2009		22,406		20,697		9,019		6,088			(9,030	)		49,180


(a)		Generation represents the three segments, Mid-Atlantic, Midwest and South as shown below. Intersegment revenues for the three months ended June 30, 2010 and 2009, represent Mid-Atlantic revenue from sales to PECO of $470 million and $486 million, respectively, and Midwest revenue from sales to ComEd of $255 million and $347 million, respectively.

(b)		For the three months ended June 30, 2010 and 2009, utility taxes of $29 million and $42 million, respectively, are included in revenues and expenses for ComEd. For the three months ended June 30, 2010 and 2009, utility taxes of $67 million and $61 million, respectively, are included in revenues and expenses for PECO.

(c)		The intersegment profit associated with Generation’s sale of AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 2 of the 2009 Form 10-K for additional information on AECs. For Exelon, these amounts are included in operating revenues in the Consolidated Statements of Operations.


	Mid-Atlantic		Midwest		South			Other(b)			Generation
Total revenues(a):
2010	$	751	$	1,383	$	150		$	69		$	2,353
2009		834		1,344		171			29			2,378
Revenues net of purchased power and fuel expense:
2010	$	583	$	1,016	$	(43	)	$	(102	)	$	1,454
2009		682		1,017		(25	)		(187	)		1,487


(a)		Includes all sales to third parties and affiliated sales to ComEd and PECO. For the three months ended June 30, 2010 and 2009, there were no transactions among Generation’s reportable segments which would result in intersegment revenue for Generation.

(b)		Includes retail gas, proprietary trading, other revenue and mark-to-market activities as well as amounts paid related to the Illinois Settlement Legislation.

Six Months Ended June 30, 2010 and 2009


										Intersegment
	Generation (a)		ComEd		PECO		Other			Eliminations			Consolidated
Total revenues(b):
2010	$	4,773	$	2,914	$	2,724	$	359		$	(1,911	)	$	8,859
2009		4,979		2,942		2,718		391			(2,167	)		8,863
Intersegment revenues(c):
2010	$	1,552	$	1	$	3	$	358		$	(1,911	)	$	3
2009		1,777		1		4		391			(2,167	)		6
Net income (loss):
2010	$	943	$	125	$	176	$	(50	)	$	—		$	1,194
2009		1,041		230		183		(76	)		(9	)		1,369


(a)		Generation represents the three segments, Mid-Atlantic, Midwest and South as shown below. Intersegment revenues for the six months ended June 30, 2010 and 2009, represent Mid-Atlantic revenue from sales to PECO of $928 million and $991 million, respectively, and Midwest revenue from sales to ComEd of $624 million and $786 million, respectively.

(b)		For the six months ended June 30, 2010 and 2009, utility taxes of $80 million and $108 million, respectively, are included in revenues and expenses for ComEd. For the six months ended June 30, 2010 and 2009, utility taxes of $130 million and $121 million, respectively, are included in revenues and expenses for PECO.

(c)		The intersegment profit associated with Generation’s sale of RECs to ComEd and AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 3 — Regulatory Issues for additional information on RECs and AECs.


	Mid-Atlantic		Midwest		South			Other(b)			Generation
Total revenues(a):
2010	$	1,531	$	2,734	$	298		$	210		$	4,773
2009		1,687		2,793		346			153			4,979
Revenues net of purchased power and fuel expense:
2010	$	1,197	$	2,010	$	(91	)	$	160		$	3,276
2009		1,377		2,090		(58	)		(5	)		3,404


(a)		Includes all sales to third parties and affiliated sales to ComEd and PECO. For the six months ended June 30, 2010 and 2009, there were no transactions among Generation’s reportable segments which would result in intersegment revenue for Generation.

(b)		Includes retail gas, proprietary trading, other revenue and mark-to-market activities as well as amounts paid related to the Illinois Settlement Legislation.

Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Jun. 30, 2010
Basis of Presentation (Policies) [Abstract]
Nature of Operations	Exelon is a utility services holding company engaged, through its principal subsidiaries, in the generation and energy delivery businesses. The generation business consists of the electric generating facilities, the wholesale energy marketing operations and competitive retail supply operations of Generation. The energy delivery businesses include the purchase and regulated retail sale of electricity and the provision of distribution and transmission services by ComEd in northern Illinois, including the City of Chicago, and by PECO in southeastern Pennsylvania, including the City of Philadelphia, and the purchase and regulated retail sale of natural gas and the provision of distribution services by PECO in the Pennsylvania counties surrounding the City of Philadelphia. Through its business services subsidiary, BSC, Exelon provides its subsidiaries with a variety of support services at cost, including legal, human resources, financial, information technology and supply management services. The costs of BSC, including support services, are directly charged or allocated to the applicable subsidiaries using a cost-causative allocation method. Corporate governance type costs that cannot be directly assigned are allocated based on a Modified Massachusetts formula, which is a method that utilizes a combination of gross revenues, total assets, and direct labor costs for the allocation base. The results of Exelon’s corporate operations are presented as “Other” within the notes to the consolidated financial statements and include intercompany eliminations unless otherwise disclosed. Exelon owns 100% of all of its significant consolidated subsidiaries, either directly or indirectly, except for Exelon SHC, LLC, of which Generation owns 99% and the remaining 1% is indirectly owned by Exelon and is eliminated in Exelon’s consolidated financial statements, ComEd, of which Exelon owns more than 99%, and PECO, of which Exelon owns 100% of the common stock but none of PECO’s preferred securities. Exelon has reflected the third-party interests in ComEd, which totaled less than $1 million at June 30, 2010, as equity, and PECO’s preferred securities as preferred securities of subsidiary in its consolidated financial statements. Exelon’s consolidated financial statements include the accounts of entities in which Exelon has a controlling financial interest, other than certain financing trusts of ComEd and PECO, and Generation’s and PECO’s proportionate interests in jointly owned electric utility property, after the elimination of intercompany transactions. A controlling financial interest is evidenced by either a voting interest greater than 50% or the results of a model that identifies Exelon or one of its subsidiaries as the primary beneficiary of a VIE. Investments and joint ventures in which Exelon does not have a controlling financial interest and certain financing trusts of ComEd and PECO are accounted for under the equity or cost method of accounting.
Consolidation Policy	Each of Generation’s, ComEd’s and PECO’s consolidated financial statements includes the accounts of their subsidiaries. All intercompany transactions have been eliminated.
Basis of Accounting	The accompanying consolidated financial statements as of June 30, 2010 and 2009 and for the three and six months then ended are unaudited but, in the opinion of the management of each of Exelon, Generation, ComEd and PECO, include all adjustments that are considered necessary for a fair presentation of its respective financial statements in accordance with GAAP. All adjustments are of a normal, recurring nature, except as otherwise disclosed. The December 31, 2009 Consolidated Balance Sheets were taken from audited financial statements. Certain prior year amounts in Exelon’s, Generation’s and ComEd’s Consolidated Statements of Cash Flows and in ComEd’s and PECO’s Consolidated Balance Sheets have been reclassified between line items for comparative purposes. The reclassifications did not affect Exelon’s, Generation’s or ComEd’s cash flows from operating activities or ComEd’s and PECO’s financial position. These Combined Notes to Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These notes should be read in conjunction with the Notes to Consolidated Financial Statements of Exelon, Generation, ComEd and PECO included in ITEM 8 of their 2009 Annual Report on Form 10-K.
Variable Interest Entities	*Variable Interest Entities (Exelon, Generation, ComEd and PECO)* Under the applicable authoritative guidance, VIEs are legal entities that possess any of the following characteristics: an insufficient amount of equity at risk to finance their activities, equity owners who do not have the power to direct the significant activities of the entity (or have voting rights that are disproportionate to their ownership interest), or where equity holders do not receive expected losses or returns significant to the VIE. Companies are required to consolidate a VIE if they are its primary beneficiary. Generation Generation’s wholesale operations include the physical delivery and marketing of power obtained through its generating capacity, and long-, intermediate- and short-term contracts. Generation also has contracts to purchase fuel supplies for nuclear and fossil generation. These contracts and Generation’s membership in Nuclear Electric Insurance Limited are discussed in further detail in Note 18 of the 2009 Form 10-K. Generation has evaluated these contracts and determined that either it has no variable interest in an entity or, where Generation does have a variable interest in an entity, it is not the primary beneficiary and, therefore, consolidation is not required. Several of Generation’s long-term PPAs have been determined to be operating leases that have no residual value guarantees, bargain purchase options or other provisions that would cause these operating leases to be variable interests and, therefore, not subject to this guidance. For contracts where Generation has a variable interest, Generation has considered which interest holder has the power to direct the activities that most significantly impact the economic performance of the VIE and thus is considered the primary beneficiary and is required to consolidate the entity. The primary beneficiary must also have exposure to significant losses or the right to receive significant benefits from the VIE. In general, the most significant activity of the VIEs is the operation and maintenance of the facilities, which provides the operator with the power to direct the VIEs’ activities. Facilities represent power plants, sources of uranium and fossil fuels, or plants used in the uranium conversion, enrichment and fabrication process. Generation does not have control over the operation and maintenance of the facilities considered VIEs and it does not bear operational risk of the facilities. Furthermore, Generation has no debt or equity investments in the entities, under the contracts Generation receives less than the majority of the output of the remaining expected useful life of the facilities, and Generation does not provide any other financial support through liquidity arrangements, guarantees or other commitments other than purchase commitments described in Note 12—Commitments and Contingencies. Upon consideration of these factors, Generation does not consider itself to be the primary beneficiary of these VIEs and, accordingly, has determined that consolidation is not required. Generation has aggregated its contracts with VIEs into two categories, energy commitments and fuel purchase obligations, based on the similar risk characteristics and significance to Generation. As of the balance sheet date, the carrying amount of assets and liabilities in Generation’s Consolidated Balance Sheet that relate to its involvement with VIEs are predominately related to working capital accounts and generally represent the amounts owed by Generation for the deliveries associated with the current billing cycle under the contracts. Further, Generation has not provided or guaranteed any debt or equity support, liquidity arrangements, performance guarantees or other commitments associated with these contracts, so there is no significant potential exposure to loss as a result of its involvement with the VIEs. ComEd and PECO ComEd’s retail operations include the purchase of electricity and RECs through procurement contracts of varying durations. PECO’s retail operations include the purchase of electricity, AECs and natural gas through procurement contracts of varying durations. These contracts are discussed in further detail in Notes 2 and 18 of the 2009 Form 10-K. ComEd and PECO have evaluated these contracts and determined that either they have no variable interest in a VIE or where ComEd or PECO do have a variable interest in a VIE as described below, it is not the primary beneficiary and, therefore, consolidation is not required. For contracts where ComEd or PECO has a variable interest, ComEd or PECO has considered which interest holder has the power to direct the activities that most significantly impact the economic performance of the VIE. In general, the most significant activity of the VIEs is the operation and maintenance of their production or procurement processes related to electricity, RECs, AECs or natural gas. ComEd and PECO do not have control over the operation and maintenance of the entities considered VIEs and they do not bear operational risk related to their activities. Furthermore, ComEd and PECO have no debt or equity investments in the VIEs and do not provide any other financial support through liquidity arrangements, guarantees or other commitments other than purchase commitments described in Note 12—Commitments and Contingencies. Accordingly, ComEd and PECO do not consider themselves to be the primary beneficiary of these VIEs. As of the balance sheet date, the carrying amounts of assets and liabilities in ComEd’s and PECO’s Consolidated Balance Sheet that relate to their involvement with these VIEs are predominately related to working capital accounts and generally represent the amounts owed by ComEd and PECO for the purchases associated with the current billing cycle under the contracts. The financing trust of ComEd, ComEd Financing III, and the financing trusts of PECO, PECO Trust III and PECO Trust IV, are not consolidated in Exelon’s, ComEd’s or PECO’s financial statements. These financing trusts were created to issue mandatorily redeemable trust preferred securities. ComEd and PECO have concluded that they do not have a variable interest in ComEd Financing III, PECO Trust III or PECO Trust IV as each Registrant financed its equity interest in the financing trusts through the issuance of subordinated debt and, therefore, has no equity at risk. ComEd and PECO, as the sponsors of the financing trusts, are obligated to pay the operating expenses of the trusts. PECO PETT, a financing trust, was created by PECO to purchase and own Intangible Transition Property (ITP) and to issue transition bonds to securitize $5 billion of PECO’s stranded cost recovery authorized by the PAPUC pursuant to the Competition Act. PECO made an initial capital contribution of $25 million to PETT in 1998. ITP represents the irrevocable right of PECO to collect intangible transition charges (ITC). ITC consists of the portion of CTCs that were sold by PECO to PETT and securitized through the various issuances of PETT’s transition bonds from 1999 through 2001 as authorized by the PAPUC and provides PETT with an asset sufficient to recover the aggregate principal amount of the transition bonds issued, plus amounts sufficient to provide for the credit enhancement, interest payments, servicing fees and other expenses relating to the transition bonds. PECO does not provide ongoing financial support to PETT or guarantee PETT’s performance, and the transition bondholders do not have recourse to PECO. PECO has continuing involvement in PETT in its role as the servicer of the ITC collections, for which PECO receives a fee. During the three and six months ended June 30, 2010, net pre-tax losses of $5 million and $12 million, respectively, related to PETT’s results of operations are reflected in PECO’s Consolidated Statements of Operations. PETT was consolidated in Exelon’s and PECO’s financial statements on January 1, 2010 pursuant to authoritative guidance relating to the consolidation of VIEs that became effective at that date. Under previously issued authoritative guidance, PETT was deconsolidated based on the prescribed quantitative approach, based on expected losses, of identifying the primary beneficiary. PECO has concluded that it is the primary beneficiary of PETT due to PECO’s involvement in the design of PETT and through its role as servicer of the ITC collections. Additionally, PECO has the right to dissolve PETT and receive any of its remaining assets following retirement of the transition bonds and payment of PETT’s other expenses. The consolidation of PETT did not have a significant impact on PECO’s results of operations or statement of cash flows. PETT’s assets are restricted for the sole purpose of satisfying PETT’s obligation to its transition bondholders and payment of various administrative fees as outlined in the transition bond transaction documents. As of June 30, 2010, PETT’s restricted cash balance on PECO’s Consolidated Balance Sheet was $426 million. As of June 30, 2010, PETT’s long-term debt to transition bondholders on PECO’s Consolidated Balance Sheet was $404 million, all of which is classified as long-term debt due within one year. Upon retirement of the outstanding transition bonds on September 1, 2010 and dissolution of PETT, the remaining restricted cash balance will be remitted to PECO. During the three and six months ended June 30, 2010, PECO recognized interest expense on PETT’s transition bonds of $7 million and $18 million, respectively, which is reflected in PECO’s Consolidated Statement of Operations. See Note 5 — Debt and Credit Agreements for further information regarding PETT’s debt to bondholders.

New Accounting Pronouncements (Policies)	6 Months Ended
New Accounting Pronouncements (Policies)	Jun. 30, 2010
New Accounting Pronouncements (Policies) [Abstract]
New Accounting Pronouncements Adopted	*Transfers of Financial Assets* In June 2009, the FASB issued authoritative guidance amending the accounting for transfers of financial assets. This guidance was effective and applied prospectively for the Registrants beginning January 1, 2010. The impact of the adoption for Exelon and PECO and relevant disclosure is included in Note 5 — Debt and Credit Agreements. The adoption of this guidance did not impact Generation’s or ComEd’s results of operations, cash flows or financial positions. *Consolidation of Variable Interest Entities* In June 2009, the FASB issued authoritative guidance to amend the manner in which entities evaluate whether consolidation is required for VIEs. The model for determining which enterprise has a controlling financial interest and is the primary beneficiary of a VIE has changed significantly under the new guidance. Furthermore, this guidance requires that companies continually evaluate VIEs for consolidation rather than assessing based upon the occurrence of triggering events. This revised guidance also requires enhanced disclosures about how a company’s involvement with a VIE affects its financial statements and exposure to risks. This guidance became effective for the Registrants on January 1, 2010. The impact of the adoption for Exelon and PECO and relevant disclosure is included in Note 1 — Basis of Presentation. The adoption of this guidance did not impact Generation’s or ComEd’s results of operations, cash flows or financial positions. *Fair Value Measurements Disclosures* In January 2010, the FASB issued authoritative guidance intended to improve disclosures about fair value measurements. The guidance requires entities to disclose significant transfers in and out of fair value hierarchy levels and the reasons for the transfers. Additionally, the guidance clarifies that a reporting entity should provide fair value measurements for each class of assets and liabilities and disclose the inputs and valuation techniques used for fair value measurements using significant other observable inputs (Level 2) and significant unobservable inputs (Level 3). Currently, the Registrants’ mark-to-market derivative assets and liabilities and NDT fund investments are the only fair value measurements affected by this guidance. This guidance became effective for interim and annual periods beginning after December 15, 2009, except for the disclosures about purchases, sales, issuances and settlements in the Level 3 reconciliation, which will be effective for interim and annual periods beginning after December 15, 2010. As this guidance provides only disclosure requirements, the adoption of this standard did not impact the Registrants’ results of operations, cash flows or financial positions. See Note 4 — Fair Value of Financial Assets and Liabilities for additional information.
New Accounting Pronouncements Not Yet Adopted	*Revenue Arrangements with Multiple Deliverables* In October 2009, the FASB issued authoritative guidance that amends existing guidance for identifying separate deliverables in a revenue-generating transaction where multiple deliverables exist, and provides guidance for allocating and recognizing revenue based on those separate deliverables. The guidance is expected to result in more multiple-deliverable arrangements being separable than under current guidance. This guidance is effective for the Registrants beginning on January 1, 2011 and is required to be applied prospectively to new or significantly modified revenue arrangements. The Registrants are currently assessing the effects this guidance may have on their consolidated financial statements.

Fair Value of Financial Assets and Liabilities (Policies)	6 Months Ended
	Jun. 30, 2010
Fair Value Assets Measured on Recurring Basis Valuation Techniques
Cash Equivalents Valuation Techniques Used to Determine Fair Value	Cash Equivalents (Exelon, Generation, ComEd and PECO). The Registrants’ cash equivalents include investments with maturities of three months or less when purchased. The cash equivalents shown in the fair value tables are comprised of investments in mutual and money market funds. The fair values of the shares of these funds are based on observable market prices and, therefore, have been categorized in Level 1 in the fair value hierarchy.
Nuclear Decommissioning Trust Fund Investments Valuation Techniques Used to Determine Fair Value	Nuclear Decommissioning Trust Fund Investments (Exelon and Generation). The trust fund investments have been established to satisfy Exelon’s and Generation’s nuclear decommissioning obligations as required by the NRC The NDT funds hold debt and equity securities directly and indirectly through commingled funds. Generation’s investment policies place limitations on the types and investment grade ratings of the securities that may be held by the trusts. These policies restrict the trust funds from holding alternative investments and limit the trust funds’ exposures to investments in highly illiquid markets. Investments with maturities of three months or less when purchased, including certain short-term fixed income securities, are considered cash equivalents and included in the recurring fair value measurements hierarchy as Level 1 or Level 2. With respect to individually held equity securities, the trustees obtain prices from pricing services, whose prices are obtained from direct feeds from market exchanges, which Generation is able to independently corroborate. The fair values of equity securities held directly by the trust funds are based on quoted prices in active markets and are categorized in Level 1. Equity securities held individually are primarily traded on the New York Stock Exchange and NASDAQ-Global Select Market, which contain only actively traded securities due to the volume trading requirements imposed by these exchanges. For fixed income securities, multiple prices from pricing services are obtained from pricing vendors whenever possible, which enables cross-provider validations in addition to checks for unusual daily movements. A primary price source is identified based on asset type, class or issue for each security. The trustees monitor prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the portfolio managers challenge an assigned price and the trustees determine that another price source is considered to be preferable. Generation has obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, Generation selectively corroborates the fair values of securities by comparison to other market-based price sources. U.S. Treasury securities are categorized as Level 1 because they trade in a highly liquid and transparent market. The fair values of fixed income securities, excluding U.S. Treasury securities, are based on evaluated prices that reflect observable market information, such as actual trade information or similar securities, adjusted for observable differences and are categorized in Level 2. Commingled funds, which are similar to mutual funds, are maintained by investment companies and hold certain investments in accordance with a stated set of fund objectives. The fair values of short-term commingled funds held within the trust funds, which generally hold short-term fixed income securities and are not subject to restrictions regarding the purchase or sale of shares, are derived from observable prices. The objectives of the remaining commingled funds in which Exelon and Generation invest primarily seek to track the performance of certain equity indices by purchasing equity securities to replicate the capitalization and characteristics of the indices. In general, equity commingled funds are redeemable on the 15th of the month and the last business day of the month; however, the fund manager may designate any day as a valuation date for the purpose of purchasing or redeeming units. Effective December 31, 2009, commingled funds are categorized in Level 2 because the fair value of the funds are based on NAVs per fund share (the unit of account), primarily derived from the quoted prices in active markets on the underlying equity securities. See Note 10 — Nuclear Decommissioning for further discussion on the NDT fund investments.
Rabbi Trust Investments Valuation Techniques Used to Determine Fair Value	Rabbi Trust Investments (Exelon, Generation, ComEd and PECO). The Rabbi trusts were established to hold assets related to deferred compensation plans existing for certain active and retired members of Exelon’s executive management and directors. The investments in the Rabbi trusts are included in investments in the Registrants’ Consolidated Balance Sheets. The fair values of the shares of the funds are based on observable market prices and, therefore, have been categorized in Level 1 in the fair value hierarchy.
Mark-to-Market Valuation Techniques Used to Determine Fair Value	Mark-to-Market Derivatives (Exelon, Generation, ComEd and PECO). Derivative contracts are traded in both exchange-based and non-exchange-based markets. Exchange-based derivatives that are valued using unadjusted quoted prices in active markets are categorized in Level 1 in the fair value hierarchy. Certain non-exchange-based derivatives are valued using indicative price quotations available through brokers or over-the-counter, on-line exchanges and are categorized in Level 2. These price quotations reflect the average of the bid-ask, mid-point prices and are obtained from sources that the Registrants believe provide the most liquid market for the commodity. The price quotations are reviewed and corroborated to ensure the prices are observable and representative of an orderly transaction between market participants. This includes consideration of actual transaction volumes, market delivery points, bid-ask spreads and contract duration. The remainder of non-exchange-based derivative contracts is valued using the Black model, an industry standard option valuation model. The Black model takes into account inputs such as contract terms, including maturity, and market parameters, including assumptions of the future prices of energy, interest rates, volatility, credit worthiness and credit spread. For non-exchange-based derivatives that trade in liquid markets, such as generic forwards, swaps and options, model inputs are generally observable. Such instruments are categorized in Level 2. The Registrants’ non-exchange-based derivatives are predominately at liquid trading points. For non-exchange-based derivatives that trade in less liquid markets with limited pricing information, such as the financial swap contract between Generation and ComEd, model inputs generally would include both observable and unobservable inputs. These valuations may include an estimated basis adjustment from an illiquid trading point to a liquid trading point for which active price quotations are available. For valuations that include both observable and unobservable inputs, if the unobservable input is determined to be significant to the overall inputs, the entire valuation is categorized in Level 3. This includes derivatives valued using indicative price quotations whose contract tenure extends into unobservable periods. In instances where observable data is unavailable, consideration is given to the assumptions that market participants would use in valuing the asset or liability. This includes assumptions about market risks such as liquidity, volatility and contract duration. Such instruments are categorized in Level 3 as the model inputs generally are not observable. The Registrants consider credit and nonperformance risk in the valuation of derivative contracts categorized in Level 1, 2 and 3, including both historical and current market data in its assessment of credit and nonperformance risk by counterparty. The impacts of credit and nonperformance risk were not material to the financial statements. Transfers in and out of levels are recognized as of the beginning of the month the transfer occurred. Given derivatives categorized within Level 1 are valued using exchange-based quoted prices within observable periods, transfers between level 2 and level 1 generally do not occur. Transfers in and out of level 2 and level 3 generally occur when the contract tenure becomes more observable. Exelon may utilize fixed-to-floating interest rate swaps, which are typically designated as fair value hedges, as a means to achieve its targeted level of variable-rate debt as a percent of total debt. In addition, the Registrants may utilize interest rate derivatives to lock in interest rate levels in anticipation of future financings. These interest rate derivatives are typically designated as cash flow hedges. Exelon uses a calculation of future cash inflows and estimated future outflows related to the swap agreements, which are discounted and netted to determine the current fair value. Additional inputs to the present value calculation include the contract terms, counterparty credit risk and market parameters such as interest rates and volatility. As these inputs are based on observable data and valuations of similar instruments, the interest rate swaps are categorized in Level 2 in the fair value hierarchy. See Note 6—Derivative Financial Instruments for further discussion on mark-to-market derivatives.
Deferred Compensation Obligations Valuation Techniques Used to Determine Fair Value	Deferred Compensation Obligations (Exelon, Generation, ComEd and PECO). The Registrants’ deferred compensation plans allow participants to defer certain cash compensation into a notional investment account. The Registrants include such plans in other current and noncurrent liabilities in their Consolidated Balance Sheets. The value of the Registrants’ deferred compensation obligations is based on the market value of the participants’ notional investment accounts. The notional investments are comprised primarily of mutual funds, which are based on observable market prices. However, since the deferred compensation obligations themselves are not exchanged in an active market, they are categorized in Level 2 in the fair value hierarchy.
Servicing Liability Valuation Techniques Used to Determine Fair Value	Servicing Liability (Exelon and PECO). PECO is party to an agreement with a financial institution under which it transferred an undivided interest, adjusted daily, in customer accounts receivables designated under the agreement in exchange for proceeds of $225 million, which PECO accounted for as a sale under previous guidance on accounting for transfers of financial assets. A servicing liability was recorded for the agreement in accordance with the applicable authoritative guidance for servicing of financial assets. The servicing liability was included in other current liabilities in Exelon’s and PECO’s Consolidated Balance Sheets. The fair value of the liability was determined using internal estimates based on provisions in the agreement, which were categorized as Level 3 inputs in the fair value hierarchy. The servicing liability was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.

Regulatory Matters (Tables)

6 Months Ended

Jun. 30, 2010

Regulatory Matters (Tables) [Abstract]

Regulatory assets and liabilities


June 30, 2010	Exelon		ComEd		PECO

Regulatory assets
Competitive transition charge	$	438	$	—	$	438
Pension and other postretirement benefits		2,540		—		16
Deferred income taxes		851		21		830
Smart meter program expenses		3		—		3
Smart meter accelerated depreciation		3		—		3
Debt costs		131		114		17
Severance		84		84		—
Asset retirement obligations		66		50		16
MGP remediation costs		136		97		39
RTO start-up costs		11		11		—
Under-recovered uncollectible accounts		49		49		—
Financial swap with Generation — noncurrent		—		627		—
DSP Program electric procurement contracts - noncurrent		2		—		4
DSP Program costs		6		—		6
Other		60		29		31


Noncurrent regulatory assets		4,380		1,082		1,403
Financial swap with Generation — current		—		383		—
Under-recovered energy and transmission costs current asset		14		14		—
DSP Program electric procurement contracts — current		2		—		5


Total regulatory assets	$	4,396	$	1,479	$	1,408


Regulatory liabilities
Nuclear decommissioning (a)	$	2,069	$	1,797	$	272
Removal costs		1,229		1,229		—
Refund of PURTA taxes		4		—		4
Energy efficiency and demand response programs		41		19		22
Other		1		—		1


Noncurrent regulatory liabilities		3,344		3,045		299
Over-recovered energy and transmission costs current liability		51		13		38


Total regulatory liabilities	$	3,395	$	3,058	$	337


December 31, 2009	Exelon		ComEd		PECO
Regulatory assets
Competitive transition charge	$	883	$	—	$	883
Pension and other postretirement benefits		2,634		—		19
Deferred income taxes		842		20		822
Debt costs		144		125		19
Severance		95		95		—
Asset retirement obligations		65		49		16
MGP remediation costs		143		103		40
RTO start-up costs		12		12		—
Financial swap with Generation—noncurrent		—		669		—
DSP Program electric procurement contracts		2		—		4
DSP Program costs		5		—		5
Other		47		23		26


Noncurrent regulatory assets		4,872		1,096		1,834
Financial swap with Generation—current		—		302		—
Under-recovered energy and transmission costs current asset		56		56		—


Total regulatory assets	$	4,928	$	1,454	$	1,834


Regulatory liabilities
Nuclear decommissioning (a)	$	2,229	$	1,918	$	311
Removal costs		1,212		1,212		—
Refund of PURTA taxes		4		—		4
Deferred taxes		30		—		—
Energy efficiency and demand response programs		15		15		—
Other		2		—		2


Noncurrent regulatory liabilities		3,492		3,145		317
Over-recovered energy and transmission costs current liability		33		11		22


Total regulatory liabilities	$	3,525	$	3,156	$	339


(a)		These amounts represent estimated future nuclear decommissioning costs that are less than the associated NDT fund assets. These regulatory liabilities have an equal and offsetting noncurrent receivable from affiliate at ComEd and PECO, and a noncurrent payable to affiliate recorded at Generation equal to the total regulatory liability at Exelon, ComEd and PECO. See Note 10 — Nuclear Decommissioning for additional information on the NDT fund activity.

Operating and Maintenance for Regulatory Required Programs


For the Three Months Ended June 30, 2010	Exelon		ComEd			PECO
Energy efficiency and demand response programs	$	33	$	20	(a)	$	13
Purchased power administrative costs		1		1			—


Total operating and maintenance for regulatory required programs	$	34	$	21		$	13


For the Six Months Ended June 30, 2010	Exelon		ComEd			PECO
Energy efficiency and demand response programs	$	58	$	38	(a)	$	20
Purchased power administrative costs		2		2			—
Consumer education program		1		—			1	(b)


Total operating and maintenance for regulatory required programs	$	61	$	40		$	21


For the Three Months Ended June 30, 2009	Exelon		ComEd
Energy efficiency and demand response programs	$	13	$	13	(a)
Purchased power administrative costs		1		1


Total operating and maintenance for regulatory required programs	$	14	$	14


For the Six Months Ended June 30, 2009	Exelon		ComEd
Energy efficiency and demand response programs	$	23	$	23	(a)
Purchased power administrative costs		2		2


Total operating and maintenance for regulatory required programs	$	25	$	25


(a)		As a result of the Illinois Settlement Legislation, Illinois utilities are required to provide energy efficiency and demand response programs.

(b)		In 2009, the PAPUC authorized PECO to collect a surcharge to recover expenditures associated with PECO’s approved consumer education plan related to the transition to competitive energy market prices.

Fair Value of Financial Assets and Liabilities (Tables)

6 Months Ended

Jun. 30, 2010

Fair value of financial liabilities recorded at the carrying amount


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	11,026	$	12,077	$	11,634	$	12,223
Long-term debt of variable interest entity due within one year (a)		404		408		—		—
Long-term debt to PETT due within one year (a)		—		—		415		426
Long-term debt to financing trusts		390		332		390		325
Spent nuclear fuel obligation		1,018		864		1,017		832
Preferred securities of subsidiary		87		70		87		63


(a)		On January 1, 2010, PETT was consolidated in Exelon’s Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 — Basis of Presentation for additional information.

Assets and liabilities measured and recorded at fair value on recurring basis


As of June 30, 2010	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	1,455		$	—		$	—		$	1,455
Nuclear decommissioning trust fund investments
Cash equivalents		53			73			—			126
Equity securities(b)		1,414			—			—			1,414
Commingled funds(c)		—			1,920			—			1,920
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		702			106			—			808
Debt securities issued by states of the United States and political subdivisions of the states		—			440			—			440
Corporate debt securities		—			719			—			719
Federal agency mortgage-backed securities		—			761			—			761
Commercial mortgage-backed securities (non-agency)		—			125			—			125
Residential mortgage-backed securities (non-agency)		—			8			—			8
Other debt obligations		—			74			1			75

Nuclear decommissioning trust fund investments subtotal(d)		2,169			4,226			1			6,396


Rabbi trust investments
Cash equivalents		24			—			—			24
Mutual funds(e)		13			—			—			13

Rabbi trust investments subtotal		37			—			—			37


Mark-to-market derivative assets
Cash flow hedges		—			973			4			977
Other derivatives		3			1,852			72			1,927
Proprietary trading		—			287			47			334
Effect of netting and allocation of collateral received/paid(f)		(6	)		(2,154	)		(33	)		(2,193	)

Mark-to-market assets(g)		(3	)		958			90			1,045


Total assets		3,658			5,184			91			8,933


Liabilities
Mark-to-market derivative liabilities
Cash flow hedges		—			(79	)		(3	)		(82	)
Other derivatives		(3	)		(948	)		(29	)		(980	)
Proprietary trading		—			(282	)		(13	)		(295	)
Effect of netting and allocation of collateral received/paid(f)		3			1,270			22			1,295

Mark-to-market liabilities(g)		—			(39	)		(23	)		(62	)

Deferred compensation		—			(70	)		—			(70	)


Total liabilities		—			(109	)		(23	)		(132	)


Total net assets	$	3,658		$	5,075		$	68		$	8,801


As of December 31, 2009	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	1,845		$	—		$	—		$	1,845
Nuclear decommissioning trust fund investments
Cash equivalents		2			120			—			122
Equity securities(b)		1,528			—			—			1,528
Commingled funds(c)		—			2,086			—			2,086
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		511			119			—			630
Debt securities issued by states of the United States and political subdivisions of the states		—			454			—			454
Corporate debt securities		—			710			—			710
Federal agency mortgage-backed securities		—			887			—			887
Commercial mortgage-backed securities (non-agency)		—			91			—			91
Residential mortgage-backed securities (non-agency)		—			9			—			9
Other debt obligations		—			76			—			76

Nuclear decommissioning trust fund investments subtotal(d)		2,041			4,552			—			6,593


Rabbi trust investments
Cash equivalents		28			—			—			28
Mutual funds(e)		13			—			—			13

Rabbi trust investments subtotal		41			—			—			41


Mark-to-market derivative net (liabilities) assets(f)(g)		(4	)		852			(44	)		804


Total assets (liabilities)		3,923			5,404			(44	)		9,283


Liabilities
Deferred compensation		—			(82	)		—			(82	)
Servicing liability		—			—			(2	)		(2	)


Total liabilities		—			(82	)		(2	)		(84	)


Total net assets	$	3,923		$	5,322		$	(46	)	$	9,199


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 — Basis of Presentation for additional information on the VIE.

(b)		Generation’s NDT funds hold equity portfolios whose performance is benchmarked against the S&P 500 Index, Russell 3000 Index or Morgan Stanley Capital International Europe, Australasia and Far East (EAFE) Index.

(c)		Generation’s NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S&P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.

(d)		Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.

(e)		Excludes $22 million and $23 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009, respectively.

(f)		Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2009.

(g)		The Level 3 balance does not include current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation’s financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010 and a noncurrent asset of $2 million at December 31, 2009, respectively, related to the fair value of Generation’s block contracts with PECO, which eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of March 31, 2010	$	—	$	33		$	33
Total realized / unrealized gains (losses)
Included in other comprehensive income		—		(11	)(c)		(11	)
Included in regulatory assets		—		1			1
Change in collateral		—		9			9
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		24			24


Balance as of June 30, 2010	$	1	$	67		$	68

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—	$	1		$	1


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Six Months Ended June 30, 2010 (a)	Liability			Investments		Derivatives			Total
Balance as of December 31, 2009	$	(2	)	$	—	$	(44	)	$	(46	)
Total realized / unrealized gains (losses)
Included in income		2	(d)		—		80	(b)		82
Included in other comprehensive income		—			—		7	(c)		7
Included in regulatory assets		—			—		(2	)		(2	)
Change in collateral		—			—		(8	)		(8	)
Purchases, sales, issuances, and settlements
Purchases		—			1		11			12
Transfers out of Level 3 — Liability		—			—		23			23


Balance as of June 30, 2010	$	—		$	1	$	67		$	68

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—		$	—	$	78		$	78


(a)		Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

(b)		Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.

(c)		Excludes increases/(decreases) in fair value of ($121) million and $199 million and realized losses due to settlements of $104 million and $160 million associated with Generation’s financial swap contract with ComEd and ($1) million and $3 million of changes in fair value of Generation’s block contracts with PECO for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

(d)		The servicing liability related to PECO’s accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Three Months Ended June 30, 2009	Liability			Investments		Derivatives			Total
Balance as of March 31, 2009	$	(2	)	$	1,371	$	48		$	1,417
Total realized / unrealized gains (losses)
Included in income		—			98		(33	)(a)		65
Included in other comprehensive income		—			—		(2	)(b)		(2	)
Included in regulatory assets		—			183		(1	)		182
Purchases, sales and issuances, net		—			27		—			27

Balance as of June 30, 2009	$	(2	)	$	1,679	$	12		$	1,689

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	—		$	97	$	(21	)	$	76


				Nuclear
				Decommissioning
	Servicing			Trust Fund		Mark-to-Market
Six Months Ended June 30, 2009	Liability			Investments		Derivatives			Total
Balance as of December 31, 2008	$	(2	)	$	1,220	$	106		$	1,324
Total realized / unrealized gains (losses)
Included in income		—			41		(101	)(a)		(60	)
Included in other comprehensive income		—			—		10	(b)		10
Included in regulatory assets		—			84		(1	)		83
Purchases, sales and issuances, net		—			334		—			334
Transfers into (out of ) Level 3		—			—		(2	)		(2	)

Balance as of June 30, 2009	$	(2	)	$	1,679	$	12		$	1,689

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	—		$	40	$	(71	)	$	(31	)


(a)		Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.

(b)		Excludes increases/(decreases) in fair value of ($85) million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation’s financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All amounts eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis


	Operating		Purchased
	Revenue		Power			Fuel		Other, net
Total gains (losses) included in income for the three months ended June 30, 2010	$	15	$	(20	)	$	5	$	—
Total gains included in income for the six months ended June 30, 2010	$	13	$	36		$	31	$	2
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2010 for the three months ended June 30, 2010	$	20	$	(21	)	$	2	$	—
Change in the unrealized gains relating to assets and liabilities held as of June 30, 2010 for the six months ended June 30, 2010	$	23	$	33		$	22	$	—


	Operating			Purchased
	Revenue			Power			Fuel			Other, net
Total gains (losses) included in income for the three months ended June 30, 2009	$	(21	)	$	(10	)	$	(2	)	$	98
Total gains (losses) included in income for the six months ended June 30, 2009	$	(42	)	$	(6	)	$	(53	)	$	41
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the three months ended June 30, 2009	$	—		$	(9	)	$	(12	)	$	97
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the six months ended June 30, 2009	$	—		$	(7	)	$	(64	)	$	40

Fair value of financial liabilities recorded at the carrying amount


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	2,779	$	3,021	$	2,993	$	3,132
Spent nuclear fuel obligation		1,018		864		1,017		832

Assets and liabilities measured and recorded at fair value on recurring basis


As of June 30, 2010	Level 1			Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	790		$	—		$	—		$	790
Nuclear decommissioning trust fund investments
Cash equivalents		53			73			—			126
Equity securities(b)		1,414			—			—			1,414
Commingled funds(c)		—			1,920			—			1,920
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		702			106			—			808
Debt securities issued by states of the United States and political subdivisions of the states		—			440			—			440
Corporate debt securities		—			719			—			719
Federal agency mortgage-backed securities		—			761			—			761
Commercial mortgage-backed securities (non-agency)		—			125			—			125
Residential mortgage-backed securities (non-agency)		—			8			—			8
Other debt obligations		—			74			1			75

Nuclear decommissioning trust fund investments subtotal(d)		2,169			4,226			1			6,396

Rabbi trust investments(e)(f)		4			—			—			4
Mark-to-market derivative assets
Cash flow hedges		—			973			1,019			1,992
Other derivatives		3			1,837			72			1,912
Proprietary trading		—			287			47			334
Effect of netting and allocation of collateral received/paid (g)		(6	)		(2,154	)		(33	)		(2,193	)

Mark-to-market assets(h)		(3	)		943			1,105			2,045


Total assets		2,960			5,169			1,106			9,235


Liabilities
Mark-to-market derivative liabilities
Cash flow hedges		—			(73	)		(3	)		(76	)
Other derivatives		(3	)		(948	)		(25	)		(976	)
Proprietary trading		—			(282	)		(13	)		(295	)
Effect of netting and allocation of collateral received/paid (g)		3			1,270			22			1,295

Mark-to-market liabilities		—			(33	)		(19	)		(52	)

Deferred compensation		—			(19	)		—			(19	)


Total liabilities		—			(52	)		(19	)		(71	)


Total net assets	$	2,960		$	5,117		$	1,087		$	9,164


As of December 31, 2009	Level 1			Level 2			Level 3		Total
Assets
Cash equivalents(a)	$	1,040		$	—		$	—	$	1,040
Nuclear decommissioning trust fund investments
Cash equivalents		2			120			—		122
Equity securities(b)		1,528			—			—		1,528
Commingled funds(c)		—			2,086			—		2,086
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies		511			119			—		630
Debt securities issued by states of the United States and political subdivisions of the states		—			454			—		454
Corporate debt securities		—			710			—		710
Federal agency mortgage-backed securities		—			887			—		887
Commercial mortgage-backed securities (non-agency)		—			91			—		91
Residential mortgage-backed securities (non-agency)		—			9			—		9
Other debt obligations		—			76			—		76

Nuclear decommissioning trust fund investments subtotal(d)		2,041			4,552			—		6,593

Rabbi trust investments(e)(f)		4			—			—		4
Mark-to-market derivative net assets(g)(h)		(4	)		842			931		1,769


Total assets		3,081			5,394			931		9,406


Liabilities
Deferred compensation		—			(23	)		—		(23	)


Total liabilities		—			(23	)		—		(23	)


Total net assets	$	3,081		$	5,371		$	931	$	9,383


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b)		Generation’s NDT funds hold equity portfolios whose performance is benchmarked against the S&P 500 Index, Russell 3000 Index or Morgan Stanley Capital International EAFE Index.

(c)		Generation’s NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S&P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.

(d)		Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.

(e)		The mutual funds held by the Rabbi trusts that are invested in common stock of S&P 500 companies and Pennsylvania municipal bonds are primarily rated as investment grade.

(f)		Excludes $7 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.

(g)		Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2009.

(h)		The Level 3 balance includes current and noncurrent assets for Generation of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation’s financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010, respectively, and a noncurrent asset of $2 million at December 31, 2009, related to the fair value of Generation’s block contracts with PECO. All of the mark-to-market balances Generation carries associated with the financial swap contract with ComEd and the block contracts with PECO eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of March 31, 2010	$	—	$	1,279		$	1,279
Total realized / unrealized losses
Included in other comprehensive income		—		(237	)(c)		(237	)
Change in collateral		—		9			9
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		24			24


Balance as of June 30, 2010	$	1	$	1,086		$	1,087

The amount of total gains included in income attributed to the change in unrealized gains related to assets and liabilities held as of June 30, 2010	$	—	$	1		$	1


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Six Months Ended June 30, 2010 (a)	Investments		Derivatives			Total
Balance as of December 31, 2009	$	—	$	931		$	931
Total realized / unrealized gains
Included in income		—		80	(b)		80
Included in other comprehensive income		—		49	(c)		49
Change in collateral		—		(8	)		(8	)
Purchases, sales, issuances, and settlements
Purchases		1		11			12
Transfers out of Level 3 — Liability		—		23			23


Balance as of June 30, 2010	$	1	$	1,086		$	1,087

The amount of total gains included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2010	$	—	$	78		$	78


(a)		Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

(b)		Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.

(c)		Includes increases/(decreases) in fair value of ($121) million and $199 million and realized losses due to settlements of $104 million and $160 million associated with Generation’s financial swap contract with ComEd and ($1) million and $3 million of changes in fair value of Generation’s block contracts with PECO for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Three Months Ended June 30, 2009	Investments		Derivatives			Total
Balance as of March 31, 2009	$	1,371	$	1,230		$	2,601
Total realized / unrealized gains (losses)
Included in income		98		(33	)(a)		65
Included in other comprehensive income		—		(146	)(b)		(146	)
Included in noncurrent payables to affiliates		183		—			183
Purchases, sales, issuances and settlements, net		27		—			27

Balance as of June 30, 2009	$	1,679	$	1,051		$	2,730

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	97	$	(21	)	$	76


	Nuclear
	Decommissioning
	Trust Fund		Mark-to-Market
Six Months Ended June 30, 2009	Investments		Derivatives			Total
Balance as of December 31, 2008	$	1,220	$	562		$	1,782
Total realized / unrealized gains (losses)
Included in income		41		(101	)(a)		(60	)
Included in other comprehensive income		—		592	(b)		592
Included in noncurrent payables to affiliates		84		—			84
Purchases, sales, issuances and settlements, net		334		—			334
Transfers out of Level 3		—		(2	)		(2	)

Balance as of June 30, 2009	$	1,679	$	1,051		$	2,730

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities held as of June 30, 2009	$	40	$	(71	)	$	(31	)


(a)		Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.

(b)		Includes increases/(decreases) in fair value of ($85) million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation’s financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis


	Operating		Purchased
	Revenue		Power			Fuel		Other, net
Total gains (losses) included in income for the three months ended June 30, 2010	$	15	$	(20	)	$	5	$	—
Total gains included in income for the six months ended June 30, 2010	$	13	$	36		$	31	$	—
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2010 for the three months ended June 30, 2010	$	20	$	(21	)	$	2	$	—
Change in the unrealized gains relating to assets and liabilities held as of June 30, 2010 for the six months ended June 30, 2010	$	23	$	33		$	22	$	—


	Operating			Purchased
	Revenue			Power			Fuel			Other, net
Total gains (losses) included in income for the three months ended June 30, 2009	$	(21	)	$	(10	)	$	(2	)	$	98
Total gains (losses) included in income for the six months ended June 30, 2009	$	(42	)	$	(6	)	$	(53	)	$	41
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the three months ended June 30, 2009	$	—		$	(9	)	$	(12	)	$	97
Change in the unrealized gains (losses) relating to assets and liabilities held as of June 30, 2009 for the six months ended June 30, 2009	$	—		$	(7	)	$	(64	)	$	40

Fair value of financial liabilities recorded at the carrying amount


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	4,712	$	5,260	$	4,711	$	5,062
Long-term debt to financing trust		206		173		206		167

Assets and liabilities measured and recorded at fair value on recurring basis


As of June 30, 2010	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents (a)	$	7	$	—		$	—		$	7
Rabbi trust investments
Cash equivalents		24		—			—			24


Total assets		31		—			—			31


Liabilities
Deferred compensation obligation		—		(7	)		—			(7	)
Mark-to-market derivative liabilities
Cash flow hedges (b)		—		(6	)		—			(6	)
Other derivatives (c)		—		—			(1,010	)		(1,010	)

Mark-to-market liabilities		—		(6	)		(1,010	)		(1,016	)


Total liabilities		—		(13	)		(1,010	)		(1,023	)


Total net assets (liabilities)	$	31	$	(13	)	$	(1,010	)	$	(992	)


As of December 31, 2009	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents (a)	$	25	$	—		$	—		$	25
Rabbi trust investments
Cash equivalents		28		—			—			28


Total assets		53		—			—			53


Liabilities
Deferred compensation obligation		—		(8	)		—			(8	)
Mark-to-market derivative liabilities (c)		—		—			(971	)		(971	)


Total liabilities		—		(8	)		(971	)		(979	)


Total net assets (liabilities)	$	53	$	(8	)	$	(971	)	$	(926	)


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b)		Cash flow hedges relating to treasury rate locks were recorded in Other current liabilities on ComEd’s Consolidated Balance Sheets.

(c)		The Level 3 balance is comprised of the current and noncurrent liability of $383 million and $627 million at June 30, 2010, respectively, and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of ComEd’s financial swap contract with Generation, which eliminates upon consolidation in Exelon’s Consolidated Financial Statements.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis


	Mark-to-Market
Three Months Ended June 30, 2010	Derivatives
Balance as of March 31, 2010	$	(1,235	)
Total realized / unrealized gains included in regulatory assets (a)		225

Balance as of June 30, 2010	$	(1,010	)


	Mark-to-Market
Six Months Ended June 30, 2010	Derivatives
Balance as of December 31, 2009	$	(971	)
Total realized / unrealized losses included in regulatory assets (a)		(39	)

Balance as of June 30, 2010	$	(1,010	)


(a)		Includes increases/(decreases) in fair value of $121 million and ($199) million and realized gains due to settlements of $104 million and $160 million associated with ComEd’s financial swap contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Mark-to-Market
Three Months Ended June 30, 2009	Derivatives
Balance as of March 31, 2009	$	(1,182	)
Total realized / unrealized gains included in regulatory assets (a)		145

Balance as of June 30, 2009	$	(1,037	)


	Mark-to-Market
Six Months Ended June 30, 2009	Derivatives
Balance as of December 31, 2008	$	(456	)
Total realized / unrealized losses included in regulatory assets (a)		(581	)

Balance as of June 30, 2009	$	(1,037	)


(a)		Includes increases/(decreases) in fair value of $85 million and ($667) million and realized gains due to settlements of $60 million and $86 million associated with ComEd’s financial swap contract with Generation for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.

Fair value of financial liabilities recorded at the carrying amount


	June 30, 2010				December 31, 2009
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
Long-term debt (including amounts due within one year)	$	2,221	$	2,461	$	2,221	$	2,346
Long-term debt of variable interest entity due within one year (a)		404		408		—		—
Long-term debt to PETT due within one year (a)		—		—		415		426
Long-term debt to financing trusts		184		159		184		158
Preferred securities		87		70		87		63


(a)		On January 1, 2010, PETT was consolidated in PECO’s Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 — Basis of Presentation for additional information.

Assets and liabilities measured and recorded at fair value on recurring basis


As of June 30, 2010	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	612	$	—		$	—		$	612
Rabbi trust investments — mutual funds(b)(c)		7		—			—			7


Total assets		619		—			—			619


Liabilities
Deferred compensation obligation		—		(22	)		—			(22	)
Mark-to-market derivative liabilities(d)		—		—			(9	)		(9	)


Total liabilities		—		(22	)		(9	)		(31	)


Total net assets (liabilities)	$	619	$	(22	)	$	(9	)	$	588


As of December 31, 2009	Level 1		Level 2			Level 3			Total
Assets
Cash equivalents(a)	$	281	$	—		$	—		$	281
Rabbi trust investments — mutual funds(b)(c)		7		—			—			7


Total assets		288		—			—			288


Liabilities
Deferred compensation obligation		—		(25	)		—			(25	)
Mark-to-market derivative liabilities(d)		—		—			(4	)		(4	)
Servicing liability		—		—			(2	)		(2	)


Total liabilities		—		(25	)		(6	)		(31	)


Total net assets (liabilities)	$	288	$	(25	)	$	(6	)	$	257


(a)		Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 — Basis of Presentation for additional information on the VIE.

(b)		The mutual funds held by the Rabbi trusts invest in common stock of S&P 500 companies and Pennsylvania municipal bonds that are primarily rated as investment grade.

(c)		Excludes $11 million and $12 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.

(d)		The Level 3 balance is comprised of the current and noncurrent liability of $5 million and $4 million at June 30, 2010, respectively, and the noncurrent liability of $4 million at December 31, 2009, related to the fair value of PECO’s block contracts. These liability balances include a $3 million and $2 million current and noncurrent liability, respectively, at June 30, 2010, and a noncurrent liability of $2 million at December 31, 2009, related to the fair value of PECO’s block contracts with Generation that eliminates upon consolidation in Exelon’s Consolidated Financial Statements.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis


	Mark-to-Market
Three Months Ended June 30, 2010	Derivatives
Balance as of March 31, 2010	$	(11	)
Total unrealized gains included in regulatory assets		2	(b)

Balance as of June 30, 2010	$	(9	)


	Mark-to-Market
Six Months Ended June 30, 2010	Derivatives			Servicing Liability			Total
Balance as of December 31, 2009	$	(4	)	$	(2	)	$	(6	)
Total realized / unrealized gains (losses)
Included in net income		—			2	(a)		2
Included in regulatory assets		(5	)(b)		—			(5	)

Balance as of June 30, 2010	$	(9	)	$	—		$	(9	)


(a)		The servicing liability related to PECO’s accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 — Debt and Credit Agreements for additional information.

(b)		Includes increases/(decreases) in fair value of $1 million and ($3) associated with PECO’s block contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon’s Consolidated Financial Statements.


	Mark-to-Market
Three Months Ended June 30, 2009	Derivatives			Servicing Liability			Total
Balance as of March 31, 2009	$	—		$	(2	)	$	(2	)
Total unrealized losses included in regulatory assets		(2	)		—			(2	)

Balance as of June 30, 2009	$	(2	)	$	(2	)	$	(4	)


	Mark-to-Market
Six Months Ended June 30, 2009	Derivatives			Servicing Liability			Total
Balance as of December 31, 2008	$	—		$	(2	)	$	(2	)
Total unrealized losses included in regulatory assets		(2	)		—			(2	)

Balance as of June 30, 2009	$	(2	)	$	(2	)	$	(4	)

Debt and Credit Agreements (Tables)

6 Months Ended

Jun. 30, 2010

Debt and Credit Agreements (Tables) [Abstract]

Commercial paper and credit facility borrowings outstanding


	June 30,		December 31,
	2010		2009
Commercial paper borrowings
Exelon Corporate	$	—	$	—
Generation		—		—
ComEd		289		—
PECO		—		—
Credit facility borrowings
ComEd	$	—	$	155

Issuance of Long-Term Debt

Company

Type

Interest Rate

Maturity

Amount(a)

Use of Proceeds

Generation

Pollution Control Notes

5.00

December 1, 2042

Used to refinance $46 million of unenhanced tax-exempt variable rate debt that was repurchased on February 23, 2009.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2020

Used to repay credit facility borrowings incurred to repurchase bonds.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2017

Used to repay credit facility borrowings incurred to repurchase bonds.

ComEd

First Mortgage Bonds(b)

Variable

March 1, 2021

Used to repay credit facility borrowings incurred to repurchase bonds.

PECO

First Mortgage Bonds

5.00

October 1, 2014

250

Used to refinance short-term debt and for other general corporate purposes.


(a)		Excludes unamortized bond discounts.

(b)		Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were remarketed in May 2009 following an earlier repurchase.

Retirement of Long-Term Debt

Company

Type

Interest Rate

Maturity

Amount

ComEd

Sinking fund debentures

4.75

December 1, 2011

Generation

Kennett Square Capital Lease

7.83

September 20, 2020

Generation

Montgomery County Series 1994 B Tax Exempt Bonds

Variable

June 1, 2029

Generation

Indiana County Series 2003 A Tax Exempt Bonds

Variable

June 1, 2027

Generation

York County Series 1993 A Tax Exempt Bonds

Variable

August 1, 2016

Company

Type

Interest Rate

Maturity

Amount

Generation

Salem County 1993 Series A Tax Exempt Bonds

Variable

March 1, 2025

Generation

Delaware County Series 1993 A Tax Exempt Bonds

Variable

August 1, 2016

Generation

Montgomery County Series 1996 A Tax Exempt Bonds

Variable

March 1, 2034

Generation

Montgomery County Series 1994 A Tax Exempt Bonds

Variable

June 1, 2029

Exelon

2005 Senior Notes

4.45

June 15, 2010

400

PECO

PETT Transition Bonds

6.52

September 1, 2010

402

During the six months ended June 30, 2009, the following long-term debt was retired:

Company

Type

Interest Rate

Maturity

Amount

Generation

Pollution Control Notes

Variable

December 1, 2042

Generation

Kennett Square Capital Lease

7.83

September 20, 2020

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2020

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2017

ComEd

First Mortgage Bonds (a)

Variable

March 1, 2021

ComEd

First Mortgage Bonds

5.70

January 15, 2009

ComEd

Sinking fund debentures

4.625-4.75

Various

PECO

PETT Transition Bonds

7.65

September 1, 2009

319

PECO

PETT Transition Bonds

6.52

March 1, 2010


(a)		Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were repurchased in May 2009 and subsequently remarketed.

Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2010

Derivatives Financial Instruments (Tables) [Abstract]

Gain or loss on the hedged items and the offsetting loss or gain on the related interest rate swaps in interest expense


	Gain (Loss) on Swaps					Gain (Loss) on Borrowings
	Six Months Ended					Six Months Ended
	June 30,					June 30,
Income Statement Classification	2010		2009			2010			2009
Interest expense	$	5	$	(6	)	$	(5	)	$	6

Summary of the derivative fair value


	Generation															ComEd									PECO			Other					Exelon
										Collateral
	Cash Flow			Other			Proprietary			and						IL Settlement			Cash Flow						Other			Other		Intercompany			Total
Derivatives	Hedges(a,d)			Derivatives			Trading			Netting(b)			Subtotal(c)			Swap(a)			Hedges(e)			Subtotal			Derivatives (d)			Derivatives		Eliminations(a)			Derivatives

Mark-to-market derivative assets (current assets)	$	581		$	1,085		$	194		$	(1,442	)	$	418		$	—		$	—		$	—		$	—		$	—	$	—		$	418

Mark-to-market derivative assets with affiliate (current assets)		386			—			—			—			386			—			—			—			—			—		(386	)		—

Mark-to-market derivative assets (noncurrent assets)		396			827			140			(751	)		612			—			—			—			—			15		—			627

Mark-to-market derivative assets with affiliate (noncurrent assets)		629			—			—			—			629			—			—			—			—			—		(629	)		—


Total mark-to-market derivative assets	$	1,992		$	1,912		$	334		$	(2,193	)	$	2,045		$	—		$	—		$	—		$	—		$	15	$	(1,015	)	$	1,045


Mark-to-market derivative liabilities (current liabilities)	$	(26	)	$	(691	)	$	(181	)	$	852		$	(46	)	$	—		$	(6	)	$	(6	)	$	(2	)	$	—	$	—		$	(54	)

Mark-to-market derivative liability with affiliate (current liabilities)		—			—			—			—			—			(383	)		—			(383	)		(3	)		—		386			—

Mark-to-market derivative liabilities (noncurrent liabilities)		(50	)		(285	)		(114	)		443			(6	)		—			—			—			(2	)		—		—			(8	)

Mark-to-market derivative liability with affiliate (noncurrent liabilities)		—			—			—			—			—			(627	)		—			(627	)		(2	)		—		629			—


Total mark-to-market derivative liabilities		(76	)		(976	)		(295	)		1,295			(52	)		(1,010	)		(6	)		(1,016	)		(9	)		—		1,015			(62	)


Total mark-to-market derivative net assets (liabilities)	$	1,916		$	936		$	39		$	(898	)	$	1,993		$	(1,010	)	$	(6	)	$	(1,016	)	$	(9	)	$	15	$	—		$	983

(a)

(b)

Represents the netting of fair value balances with the same counterparty and the application of collateral.

(c)

(d)

(e)

Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd’s Consolidated Balance Sheets.

The following table provides a summary of the derivative fair value balances recorded by the Registrants as of December 31, 2009:


	Generation															ComEd			PECO			Other					Exelon
										Collateral
	Cash Flow			Other			Proprietary			and						IL Settlement			Other			Other		Intercompany			Total
Derivatives	Hedges(a)			Derivatives			Trading			Netting(b)			Subtotal(c)			Swap(a)			Derivatives (d)			Derivatives		Eliminations(a)			Derivatives

Mark-to-market derivative assets (current assets)	$	576		$	913		$	193		$	(1,306	)	$	376		$	—		$	—		$	—	$	—		$	376

Mark-to-market derivative assets with affiliate (current assets)		302			—			—			—			302			—			—			—		(302	)		—

Mark-to-market derivative assets (noncurrent assets)		423			792			102			(678	)		639			—			—			10		—			649

Mark-to-market derivative assets with affiliate (noncurrent assets)		671			—			—			—			671			—			—			—		(671	)		—


Total mark-to-market derivative assets	$	1,972		$	1,705		$	295		$	(1,984	)	$	1,988		$	—		$	—		$	10	$	(973	)	$	1,025


Mark-to-market derivative liabilities (current liabilities)	$	(18	)	$	(743	)	$	(172	)	$	735		$	(198	)	$	—		$	—		$	—	$	—		$	(198	)

Mark-to-market derivative liability with affiliate (current liabilities)		—			—			—			—			—			(302	)		—			—		302			—

Mark-to-market derivative liabilities (noncurrent liabilities)		(42	)		(183	)		(98	)		302			(21	)		—			(2	)		—		—			(23	)

Mark-to-market derivative liability with affiliate (noncurrent liabilities)		—			—			—			—			—			(669	)		(2	)		—		671			—


Total mark-to-market derivative liabilities		(60	)		(926	)		(270	)		1,037			(219	)		(971	)		(4	)		—		973			(221	)


Total mark-to-market derivative net assets (liabilities)	$	1,912		$	779		$	25		$	(947	)	$	1,769		$	(971	)	$	(4	)	$	10	$	—		$	804


(a)		Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $302 million and $669 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.

(b)		Represents the netting of fair value balances with the same counterparty and the application of collateral.

(c)		Current and noncurrent assets are shown net of collateral of $502 million and $376 million, respectively, and current liabilities are shown inclusive of collateral of $69 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $947 million at December 31, 2009.

(d)		Includes a noncurrent liability for PECO and a noncurrent asset for Generation of $2 million related to the fair value of PECO’s block contracts with Generation. There were no netting adjustments or collateral received as of December 31, 2009.

The activity of accumulated OCI related to cash flow hedges


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Three Months Ended June 30, 2010	Location	Hedges			Hedges

Accumulated OCI derivative gain at March 31, 2010		$	1,703	(a)	$	934
Effective portion of changes in fair value			(335	)(b)		(262	)(e)
Reclassifications from accumulated OCI to net income	Operating Revenue		(211	)(c)		(148	)
Ineffective portion recognized in income	Purchased Power		1			1

Accumulated OCI derivative gain at June 30, 2010		$	1,158	(a)(d)	$	525


(a)		Includes $610 million and $746 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $4 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and March 31, 2010, respectively.

(b)		Includes a $73 million loss, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $1 million loss, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the three months ended June 30, 2010.

(c)		Includes a $63 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2010.

(d)		Excludes $5 million gains, net of taxes, related to interest rate swaps settled in 2010.

(e)		Includes $4 million of losses, net of taxes, related to the effective portion of changes in fair value of treasury rate locks at ComEd.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Six Months Ended June 30, 2010	Location	Hedges			Hedges
Accumulated OCI derivative gain at December 31, 2009		$	1,152	(a)	$	551
Effective portion of changes in fair value			334	(b)		205	(e)
Reclassifications from accumulated OCI to net income	Operating Revenue		(328	)(c)		(231	)

Accumulated OCI derivative gain at June 30, 2010		$	1,158	(a,d)	$	525


(a)		Includes $610 million and $585 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $1 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and December 31, 2009, respectively.

(b)		Includes a $122 million gain, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $2 million gain, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the six months ended June 30, 2010.

(c)		Includes a $97 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the six months ended June 30, 2010.

(d)		Excludes $5 million gains, net of taxes, related to interest rate swaps settled in 2010.

(e)		Includes $4 million of losses, net of taxes, related to the effective portion of changes in fair value of treasury rate locks at ComEd.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Three Months Ended June 30, 2009	Location	Hedges			Hedges
Accumulated OCI derivative gain at March 31, 2009		$	1,814	(a)	$	1,110
Effective portion of changes in fair value			(42	)(b)		4
Reclassifications from accumulated OCI to net income	Operating Revenue		(262	)(c)		(226	)
Ineffective portion recognized in income	Purchased Power		2			2

Accumulated OCI derivative gain at June 30, 2009		$	1,512	(a)	$	890


(a)		Includes $624 million and $712 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and March 31, 2009, respectively.

(b)		Includes a $52 million loss, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd during the three months ended June 30, 2009.

(c)		Includes a $36 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2009.


		Total Cash Flow Hedge OCI Activity,
		Net of Income Tax
		Generation			Exelon
	Income Statement	Energy-Related			Total Cash Flow
Six Months Ended June 30, 2009	Location	Hedges			Hedges
Accumulated OCI derivative gain at December 31, 2008		$	855	(a)	$	585
Effective portion of changes in fair value			1,059	(b)		654
Reclassifications from accumulated OCI to net income	Operating Revenue		(407	)(c)		(354	)
Ineffective portion recognized in income	Purchased Power		5			5

Accumulated OCI derivative gain at June 30, 2009		$	1,512	(a)	$	890


(a)		Includes $624 million and $275 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and December 31, 2008, respectively.

(b)		Includes a $401 million gain, net of taxes, of the effective portion of changes in fair value of the five-year financial swap contract with ComEd for the six months ended June 30, 2009.

(c)		Includes a $52 million loss, net of taxes, of reclassifications from accumulated OCI to recognize gains in net income related to the settlements of the five-year financial swap contract with ComEd during the six months ended June 30, 2009.

Other Derivatives - Gain (loss) and reclassification


	Exelon and Generation
	Purchased
Three Months Ended June 30, 2010	Power			Fuel		Total
Change in fair value	$	(72	)	$	25	$	(47	)
Reclassification to realized at settlement		(77	)		1		(76	)

Net mark-to-market gains (losses)	$	(149	)	$	26	$	(123	)


	Exelon and Generation
	Purchased
Six Months Ended June 30, 2010	Power			Fuel		Total
Change in fair value	$	181		$	73	$	254
Reclassification to realized at settlement		(146	)		1		(145	)

Net mark-to-market gains	$	35		$	74	$	109


	Exelon and Generation
	Purchased
Three Months Ended June 30, 2009	Power			Fuel			Total
Change in fair value	$	(114	)	$	(59	)	$	(173	)
Reclassification to realized at settlement		(50	)		53			3

Net mark-to-market losses	$	(164	)	$	(6	)	$	(170	)


	Exelon and Generation
	Purchased
Six Months Ended June 30, 2009	Power			Fuel			Total
Change in fair value	$	142		$	(102	)	$	40
Reclassification to realized at settlement		(96	)		76			(20	)

Net mark-to-market gains (losses)	$	46		$	(26	)	$	20

Change in fair value and reclassification of derivative contracts


		Three Months Ended						Six Months Ended
	Location on Income	June 30,						June 30,
	Statement	2010			2009			2010			2009
Change in fair value	Operating Revenue	$	19		$	3		$	26		$	3

Reclassification to realized at settlement	Operating Revenue		(6	)		(22	)		(12	)		(43	)


Net mark-to-market gains (losses)	Operating Revenue	$	13		$	(19	)	$	14		$	(40	)

Information on Generation's credit exposure for all derivative instruments, normal purchase normal sales, and applicable payables and receivables, net of collateral and instruments that are subject to master netting agreements


	Total						Number of		Net Exposure of
	Exposure						Counterparties		Counterparties
	Before Credit		Credit		Net		Greater than 10%		Greater than 10%
Rating as of June 30, 2010	Collateral		Collateral		Exposure		of Net Exposure		of Net Exposure
Investment grade	$	1,301	$	452	$	849		—	$	—
Non-investment grade		9		5		4		—		—
No external ratings
Internally rated — investment grade		38		5		33		—		—
Internally rated — non-investment grade		1		1		—		—		—

Total	$	1,349	$	463	$	886		—	$	—


Net Credit Exposure by Type of Counterparty	As of June 30, 2010

Financial institutions	$	307
Investor-owned utilities, marketers and power producers		490
Coal		4
Other		85

Total	$	886

Retirement Benefits (Tables)

6 Months Ended

Jun. 30, 2010

Retirement Benefits (Tables) [Abstract]

Components of Exelon's net periodic benefit costs


							Other Postretirement
	Pension Benefits						Benefits
	Three Months Ended						Three Months Ended
	June 30,						June 30,
	2010			2009			2010			2009
Service cost	$	49		$	45		$	31		$	28
Interest cost		165			162			53			50
Expected return on assets		(200	)		(194	)		(27	)		(23	)
Amortization of:
Transition obligation		—			—			2			3
Prior service cost (benefit)		3			3			(14	)		(14	)
Actuarial loss		63			49			19			22


Net periodic benefit cost	$	80		$	65		$	64		$	66


							Other Postretirement
	Pension Benefits						Benefits
	Six Months Ended						Six Months Ended
	June 30,						June 30,
	2010			2009			2010			2009
Service cost	$	96		$	89		$	62		$	56
Interest cost		330			325			107			102
Expected return on assets		(400	)		(388	)		(54	)		(47	)
Amortization of:
Transition obligation		—			—			4			5
Prior service cost (benefit)		7			7			(28	)		(28	)
Actuarial loss		127			98			37			44


Net periodic benefit cost	$	160		$	131		$	128		$	132

Pension and postretirement benefit costs table


	Three Months Ended				Six Months Ended
	June 30,				June 30,
Pension and Postretirement Benefit Costs	2010		2009		2010		2009
Generation	$	67	$	59	$	134	$	119
ComEd		53		48		106		96
PECO		12		12		24		24
BSC(a)		12		12		24		24


(a)		These amounts primarily represent amounts billed to Exelon’s subsidiaries through intercompany allocations.

Savings plan matching contributions table


	Three Months Ended				Six Months Ended
	June 30,				June 30,
Savings Plan Matching Contributions	2010		2009		2010		2009
Exelon	$	20	$	18	$	40	$	36
Generation		10		9		21		18
ComEd		6		5		11		10
PECO		2		2		4		4

Corporate Restructuring and Plant Retirements (Tables)

6 Months Ended

Jun. 30, 2010

Corporate Restructuring And Plant Retirements (Tables) [Abstract]

Total severance benefits costs, recorded as operating and maintenance expense


Severance Benefits	Generation		ComEd		PECO		Other		Exelon
Expense recorded for the three and six months ended June 30, 2009 (a)(b)	$	15	$	18	$	5	$	2	$	40


(a)		The amounts above include $8 million, $5 million and $3 million at Generation, ComEd and PECO, respectively, for amounts billed through intercompany allocations.

(b)		The severance benefits costs include $1 million of stock compensation expense collectively at Generation and ComEd for which the obligation is recorded in equity.

Activity of severance obligations for the corporate restructuring (excluding obligations recorded in equity)


Severance Benefits Obligation	Generation			ComEd			PECO			Other			Exelon
Balance at December 31, 2009	$	3		$	7		$	1		$	8		$	19
Cash payments		(2	)		(5	)		(1	)		(2	)		(10	)

Balance at June 30, 2010	$	1		$	2		$	—		$	6		$	9

Activity of severance obligations for the announced Cromby and Eddystone retirements


	Exelon and
Severance Benefits Obligation	Generation
Balance at December 31, 2009	$	7
Cash payments		(1	)
Other adjustments		(2	)

Balance at June 30, 2010	$	4

Income Taxes (Tables)

6 Months Ended

Jun. 30, 2010

Income Taxes (Tables) [Abstract]

Effective Income Tax Rate Reconciliation


For the Three Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		3.3			2.9			11.2			(6.8	)
Qualified nuclear decommissioning trust fund losses		(6.7	)		(10.0	)		—			—
Domestic production activities deduction		(2.4	)		(3.4	)		—			—
Tax exempt income		(0.2	)		(0.2	)		—			—
Amortization of investment tax credit		(0.3	)		(0.2	)		(0.4	)		(0.5	)
Plant basis differences		—			—			(0.4	)		0.4
Uncertain Tax Position Remeasurement		—			(14.9	)		47.9			—
Other		(0.4	)		(0.8	)		(0.2	)		(0.2	)


Effective income tax rate		28.3	%		8.4	%		93.1	%		27.9	%


For the Six Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		3.6			4.1			7.6			(6.0	)
Qualified nuclear decommissioning trust fund losses		(0.7	)		(1.0	)		—			—
Domestic production activities deduction		(2.1	)		(2.9	)		—			—
Tax exempt income		(0.2	)		(0.2	)		—			—
Health Care Reform Legislation (a)		3.0			1.5			2.7			2.9
Amortization of investment tax credit		(0.2	)		(0.2	)		(0.4	)		(0.4	)
Plant basis differences		—			—			(0.2	)		0.2
Uncertain Tax Position Remeasurement		—			(4.5	)		18.3			—
Other		(0.2	)		(0.3	)		0.2			(0.2	)


Effective income tax rate		38.2	%		31.5	%		63.2	%		31.5	%


(a)		See Note 7 for further discussion regarding the impact of Health Care Reform Legislation on income tax expense.


For the Three Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		—			0.7			4.6			(4.0	)
Qualified nuclear decommissioning trust fund income		5.7			7.3			—			—
Domestic production activities deduction		(0.9	)		(1.1	)		—			—
Tax exempt income		(0.1	)		(0.1	)		—			—
Nontaxable postretirement benefits		(0.2	)		(0.2	)		(0.4	)		(0.2	)
Amortization of investment tax credit		(0.1	)		(0.1	)		(0.5	)		(0.4	)
Plant basis differences		—			—			(0.3	)		0.1
Other		0.2			(0.6	)		0.2			(0.1	)


Effective income tax rate		39.6	%		40.9	%		38.6	%		30.4	%


For the Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO

U.S. Federal statutory rate		35.0	%		35.0	%		35.0	%		35.0	%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit		(0.1	)		0.5			(0.7	)		(5.4	)
Qualified nuclear decommissioning trust fund income		1.9			2.6			—			—
Domestic production activities deduction		(1.2	)		(1.6	)		—			—
Tax exempt income		(0.1	)		(0.2	)		—			—
Nontaxable postretirement benefits		(0.3	)		(0.2	)		(0.5	)		(0.3	)
Amortization of investment tax credit		(0.2	)		(0.1	)		(0.5	)		(0.4	)
Plant basis differences		—			—			(0.3	)		0.3
Other		0.1			(0.3	)		(0.1	)		0.1


Effective income tax rate		35.1	%		35.7	%		32.9	%		29.3	%

Nuclear Decommissioning (Tables)

6 Months Ended

Jun. 30, 2010

Nuclear decommissioning asset retirement obligation rollforward


	Exelon and Generation
Nuclear decommissioning ARO at December 31, 2009 (a)	$	3,260
Accretion expense		96
Costs incurred to decommission retired plants		(7	)


Nuclear decommissioning ARO at June 30, 2010 (a)	$	3,349


(a)		Includes $17 million as the current portion of the ARO at June 30, 2010 and December 31, 2009, which is included in other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Unrealized Gains (Losses) on nuclear decommissioning trust funds


	Exelon and Generation
	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2010			2009		2010			2009
Net unrealized gains (losses) on decommissioning trust funds —
Regulatory Agreement Units (a)	$	(318	)	$	426	$	(207	)	$	258
Net unrealized gains (losses) on decommissioning trust funds —
Non-Regulatory Agreement Units (b)		(94	)		115		(59	)		51


(a)		Gains and losses related to Generation’s NDT funds associated with Regulatory Agreement Units are included in regulatory liabilities on Exelon’s Consolidated Balance Sheets and noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.

(b)		Gains and losses related to Generation’s NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

Nuclear decommissioning asset retirement obligation rollforward


	Exelon and Generation
Nuclear decommissioning ARO at December 31, 2009 (a)	$	3,260
Accretion expense		96
Costs incurred to decommission retired plants		(7	)


Nuclear decommissioning ARO at June 30, 2010 (a)	$	3,349


(a)		Includes $17 million as the current portion of the ARO at June 30, 2010 and December 31, 2009, which is included in other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Unrealized Gains (Losses) on nuclear decommissioning trust funds


	Exelon and Generation
	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2010			2009		2010			2009
Net unrealized gains (losses) on decommissioning trust funds —
Regulatory Agreement Units (a)	$	(318	)	$	426	$	(207	)	$	258
Net unrealized gains (losses) on decommissioning trust funds —
Non-Regulatory Agreement Units (b)		(94	)		115		(59	)		51


(a)		Gains and losses related to Generation’s NDT funds associated with Regulatory Agreement Units are included in regulatory liabilities on Exelon’s Consolidated Balance Sheets and noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.

(b)		Gains and losses related to Generation’s NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

Earnings Per Share and Equity (Tables)

6 Months Ended

Jun. 30, 2010

Earnings Per Share and Equity (Tables) [Abstract]

Reconciliation of basic and diluted earnings per share


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2010		2009		2010		2009

Net income	$	445	$	657	$	1,194	$	1,369


Average common shares outstanding — basic		661		659		661		659
Assumed exercise of stock options, performance share awards and restricted stock		1		2		1		2


Average common shares outstanding — diluted		662		661		662		661

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2010

Accrued environmental liabilities


	Total
	Environmental		Portion of Total
	Investigation and		Related to MGP
	Remediation		Investigation and
June 30, 2010	Reserve		Remediation
Exelon	$	170	$	146
Generation		15		—
ComEd		111		104
PECO		44		42


	Total
	Environmental		Portion of Total
	Investigation and		Related to MGP
	Remediation		Investigation and
December 31, 2009	Reserve		Remediation
Exelon	$	175	$	149
Generation		17		—
ComEd		113		107
PECO		45		42

Supplemental Financial Information (Tables)

6 Months Ended

Jun. 30, 2010

Components of depreciation, amortization and accretion, and other, net


Three Months Ended June 30, 2010	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	279	$	115	$	117	$	42
Regulatory assets(a)		240		—		14		226
Nuclear fuel(b)		168		168		—		—
Asset retirement obligation accretion(c)		50		49		—		—


Total depreciation, amortization and accretion	$	737	$	332	$	131	$	268


Six Months Ended June 30, 2010	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	558	$	223	$	234	$	85
Regulatory assets(a)		475		—		27		448
Nuclear fuel(b)		323		323		—		—
Asset retirement obligation accretion(c)		99		99		—		—


Total depreciation, amortization and accretion	$	1,455	$	645	$	261	$	533


Three Months Ended June 30, 2009	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	237	$	72	$	112	$	40
Regulatory assets(a)		202		—		12		190
Nuclear fuel(b)		139		139		—		—
Asset retirement obligation accretion(c)		53		53		—		—


Total depreciation, amortization and accretion	$	631	$	264	$	124	$	230


Six Months Ended June 30, 2009	Exelon		Generation		ComEd		PECO
Depreciation, amortization and accretion
Property, plant and equipment	$	475	$	149	$	221	$	80
Regulatory assets(a)		400		—		25		375
Nuclear fuel(b)		272		272		—		—
Asset retirement obligation accretion(c)		106		105		—		—


Total depreciation, amortization and accretion	$	1,253	$	526	$	246	$	455


(a)		For PECO, primarily reflects CTC amortization.

(b)		Included in fuel expense on the Registrants’ Consolidated Statements of Operations.

(c)		Included in operating and maintenance expense on the Registrants’ Consolidated Statements of Operations.

Components of non-operating income and expenses


Three Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units (a)	$	49		$	49		$	—	$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units (a)		14			14			—		—
Net unrealized losses on decommissioning trust funds —
Regulatory Agreement Units		(318	)		(318	)		—		—
Net unrealized losses on decommissioning trust funds —
Non-Regulatory Agreement Units		(94	)		(94	)		—		—
Regulatory offset to decommissioning trust fund-related activities(b)		215			215			—		—

Total decommissioning-related activities		(134	)		(134	)		—		—

Net direct financing lease income		7			—			—		—
Interest income related to uncertain income tax positions		—			—			2		—
Other		5			1			6		(1	)


Other, net	$	(122	)	$	(133	)	$	8	$	(1	)


Six Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units(a)	$	98		$	98		$	—	$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units(a)		26			26			—		—
Net unrealized losses on decommissioning trust funds —
Regulatory Agreement Units		(207	)		(207	)		—		—
Net unrealized losses on decommissioning trust funds —
Non-Regulatory Agreement Units		(59	)		(59	)		—		—
Regulatory offset to decommissioning trust fund-related activities(b)		87			87			—		—

Total decommissioning-related activities		(55	)		(55	)		—		—

Net direct financing lease income		13			—			—		—
Interest income related to uncertain income tax positions		—			—			2		—
Other		13			1			9		4


Other, net	$	(29	)	$	(54	)	$	11	$	4


(a)		Includes investment income and realized gains and losses on sales of investments of the trust funds.

(b)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of net realized income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.


Three Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units (a)	$	10		$	10		$	—		$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units (a)		10			10			—			—
Net unrealized gains on decommissioning trust funds —
Regulatory Agreement Units		426			426			—			—
Net unrealized gains on decommissioning trust funds —
Non-Regulatory Agreement Units		115			115			—			—
Regulatory offset to decommissioning trust fund-related activities (b)		(349	)		(349	)		—			—

Total decommissioning-related activities		212			212			—			—

Net direct financing lease income		7			—			—			—
Interest income related to uncertain income tax positions (c)		38			—			59			2
Other-than-temporary impairment to Rabbi trust investments (d)		(7	)		—			(7	)		—
Other		7			3			3			1


Other, net	$	257		$	215		$	55		$	3


Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other, Net
Decommissioning-related activities:
Net realized income on decommissioning trust funds —
Regulatory Agreement Units(a)	$	28		$	28		$	—		$	—
Net realized income on decommissioning trust funds —
Non-Regulatory Agreement Units(a)		18			18			—			—
Net unrealized gains on decommissioning trust funds —
Regulatory Agreement Units		258			258			—			—
Net unrealized gains on decommissioning trust funds —
Non-Regulatory Agreement Units		51			51			—			—
Regulatory offset to decommissioning trust fund-related activities(b)		(234	)		(234	)		—			—

Total decommissioning-related activities		121			121			—			—

Investment income		1			—			—			1
Net direct financing lease income		13			—			—			—
Interest income related to uncertain income tax positions (c)		77			4			87			3
Other-than-temporary impairment to Rabbi trust investments (d)		(7	)		—			(7	)		—
Other		14			8			7			2


Other, net	$	219		$	133		$	87		$	6


(a)		Includes investment income and realized gains and losses on sales of investments of the trust funds.

(b)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of net realized income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.

(c)		Primarily includes interest income at Generation and ComEd related to the February 2009 Illinois Supreme Court decision regarding refund claims for Illinois investment tax credits, which was reversed in the third quarter of 2009. See Note 10 of the 2009 Form 10-K for additional information.

(d)		ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009.

Cash Flow Supplemental Disclosures


Six Months Ended June 30, 2010	Exelon			Generation			ComEd		PECO
Other non-cash operating activities:
Pension and non-pension postretirement benefits costs	$	288		$	134		$	106	$	24
Provision for uncollectible accounts		38			1			16		21
Stock-based compensation costs		27			—			—		—
Other decommissioning-related activity (a)		31			31			—		—
Energy-related options (b)		(36	)		(36	)		—		—


Six Months Ended June 30, 2010	Exelon			Generation			ComEd			PECO
Amortization of regulatory asset related to debt costs		12			—			11			2
Accrual for Illinois utility distribution tax refund (c)		(25	)		—			(25	)		—
Under-recovered uncollectible accounts, net (d)		(49	)		—			(49	)		—
Other		(8	)		3			1			(3	)


Total other non-cash operating activities	$	278		$	133		$	60		$	44


Changes in other assets and liabilities:
Under/over-recovered energy and transmission costs		60			—			44			16
Other current assets		(172	)		(57	)		10			(127	)(e)
Other noncurrent assets and liabilities		103			23			41			37


Total changes in other assets and liabilities	$	(9	)	$	(34	)	$	95		$	(74	)


Six Months Ended June 30, 2009	Exelon			Generation			ComEd			PECO
Other non-cash operating activities:
Pension and non-pension postretirement benefits costs	$	263		$	120		$	96		$	23
Loss in equity method investments		14			1			—			12
Provision for uncollectible accounts		65			3			25			38
Stock-based compensation costs		42			—			—			—
Other decommissioning-related activity (a)		(43	)		(43	)		—			—
Energy-related options (b)		31			31			—			—
Amortization of regulatory asset related to debt costs		14			—			12			2
Amortization of the regulatory liability related to the PURTA tax settlement (f)		(2	)		—			—			(2	)
Other-than-temporary impairment to Rabbi trust investments (g)		7			—			7			—
Other		20			1			19			10


Total other non-cash operating activities	$	411		$	113		$	159		$	83


Changes in other assets and liabilities:
Under/over-recovered energy and transmission costs		58			—			47			11
Other current assets		(150	)		(5	)		1			(137	)(e)
Other noncurrent assets and liabilities		(105	)		(16	)		(82	)		(2	)


Total changes in other assets and liabilities	$	(197	)	$	(21	)	$	(34	)	$	(128	)


(a)		Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.

(b)		Reclassification of energy-related option premiums to realized at settlement of contracts recorded in results of operations due to the settlement of the underlying transaction.

(c)		During the second quarter, ComEd recorded a reduction of $25 million to taxes other than income to reflect management’s estimate of future refunds for the 2008 and 2009 tax years associated with Illinois’ utility distribution tax based on an analysis of past refunds and interpretations of the Illinois Public Utility Act. Historically, ComEd has recorded refunds of the Illinois utility distribution tax when received. ComEd believes it now has sufficient, reliable evidence to record and support an estimated receivable associated with the anticipated refund for the 2008 and 2009 tax years.

(d)		Includes $70 million of under-recovered uncollectible accounts expense from 2008 and 2009 recorded in the first quarter of 2010 as well as subsequent adjustments to and amortization of the associated regulatory asset. ComEd is recovering these costs through a rider mechanism authorized by the ICC. See Note 3 — Regulatory Matters for additional information regarding the Illinois legislation for recovery of uncollectible accounts.

(e)		Relates primarily to prepaid utility taxes.

(f)		In March 2007, PECO prevailed in a Pennsylvania Supreme Court case in which PECO had contested the assessment of PURTA taxes applicable to 1997. As a result, PECO received approximately $38 million of real estate taxes previously remitted. This refund was recorded as a regulatory liability. PECO began amortizing this liability and refunding customers in January 2008. The regulatory liability associated with the PURTA settlement was fully amortized in January 2009.

(g)		ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009.

Accumulated Depreciation Allowance For Uncollectible Accounts


June 30, 2010	Exelon			Generation			ComEd		PECO
Property, plant and equipment:
Accumulated depreciation	$	9,341	(a)	$	4,395	(a)	$	2,240	$	2,488
Accounts receivable:
Allowance for uncollectible accounts		228			31			83		114


December 31, 2009	Exelon			Generation			ComEd		PECO
Property, plant and equipment:
Accumulated depreciation	$	9,023	(b)	$	4,214	(b)	$	2,129	$	2,442
Accounts receivable:
Allowance for uncollectible accounts		225			31			77		117


(a)		Includes accumulated amortization of nuclear fuel in the reactor core of $1,384 million.

(b)		Includes accumulated amortization of nuclear fuel in the reactor core of $1,383 million.

Accumulated Other Comprehensive Income Net Of Taxes


June 30, 2010	Exelon			Generation		ComEd			PECO
Accumulated other comprehensive income (loss)
Net unrealized gain (loss) on cash flow hedges	$	525		$	1,163	$	(4	)	$	—
Pension and non-pension postretirement benefit plans		(2,603	)		—		—			—


Total accumulated other comprehensive income (loss)	$	(2,078	)	$	1,163	$	(4	)	$	—


December 31, 2009	Exelon			Generation		ComEd		PECO
Accumulated other comprehensive income (loss)
Net unrealized gain on cash flow hedges	$	551		$	1,157	$	—	$	1
Pension and non-pension postretirement benefit plans		(2,640	)		—		—		—


Total accumulated other comprehensive income (loss)	$	(2,089	)	$	1,157	$	—	$	1

Segment Information (Tables)

6 Months Ended

Jun. 30, 2010

Segment Information (Tables) [Abstract]

Analysis and reconciliation of reportable segment information

Three Months Ended June 30, 2010 and 2009


										Intersegment
	Generation(a)		ComEd		PECO		Other			Eliminations			Exelon
Total revenues(b):
2010	$	2,353	$	1,499	$	1,269	$	177		$	(900	)	$	4,398
2009		2,378		1,389		1,204		207			(1,037	)		4,141
Intersegment revenues(c):
2010	$	725	$	—	$	1	$	177		$	(900	)	$	3
2009		833		—		2		207			(1,036	)		6
Net income (loss):
2010	$	382	$	9	$	75	$	(21	)	$	—		$	445
2009		512		116		71		(35	)		(7	)		657
Total assets:
June 30, 2010	$	22,499	$	20,870	$	9,071	$	5,384		$	(8,651	)	$	49,173
December 31, 2009		22,406		20,697		9,019		6,088			(9,030	)		49,180


(a)		Generation represents the three segments, Mid-Atlantic, Midwest and South as shown below. Intersegment revenues for the three months ended June 30, 2010 and 2009, represent Mid-Atlantic revenue from sales to PECO of $470 million and $486 million, respectively, and Midwest revenue from sales to ComEd of $255 million and $347 million, respectively.

(b)		For the three months ended June 30, 2010 and 2009, utility taxes of $29 million and $42 million, respectively, are included in revenues and expenses for ComEd. For the three months ended June 30, 2010 and 2009, utility taxes of $67 million and $61 million, respectively, are included in revenues and expenses for PECO.

(c)		The intersegment profit associated with Generation’s sale of AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 2 of the 2009 Form 10-K for additional information on AECs. For Exelon, these amounts are included in operating revenues in the Consolidated Statements of Operations.


	Mid-Atlantic		Midwest		South			Other(b)			Generation
Total revenues(a):
2010	$	751	$	1,383	$	150		$	69		$	2,353
2009		834		1,344		171			29			2,378
Revenues net of purchased power and fuel expense:
2010	$	583	$	1,016	$	(43	)	$	(102	)	$	1,454
2009		682		1,017		(25	)		(187	)		1,487


(a)		Includes all sales to third parties and affiliated sales to ComEd and PECO. For the three months ended June 30, 2010 and 2009, there were no transactions among Generation’s reportable segments which would result in intersegment revenue for Generation.

(b)		Includes retail gas, proprietary trading, other revenue and mark-to-market activities as well as amounts paid related to the Illinois Settlement Legislation.

Six Months Ended June 30, 2010 and 2009


										Intersegment
	Generation (a)		ComEd		PECO		Other			Eliminations			Consolidated
Total revenues(b):
2010	$	4,773	$	2,914	$	2,724	$	359		$	(1,911	)	$	8,859
2009		4,979		2,942		2,718		391			(2,167	)		8,863
Intersegment revenues(c):
2010	$	1,552	$	1	$	3	$	358		$	(1,911	)	$	3
2009		1,777		1		4		391			(2,167	)		6
Net income (loss):
2010	$	943	$	125	$	176	$	(50	)	$	—		$	1,194
2009		1,041		230		183		(76	)		(9	)		1,369


(a)		Generation represents the three segments, Mid-Atlantic, Midwest and South as shown below. Intersegment revenues for the six months ended June 30, 2010 and 2009, represent Mid-Atlantic revenue from sales to PECO of $928 million and $991 million, respectively, and Midwest revenue from sales to ComEd of $624 million and $786 million, respectively.

(b)		For the six months ended June 30, 2010 and 2009, utility taxes of $80 million and $108 million, respectively, are included in revenues and expenses for ComEd. For the six months ended June 30, 2010 and 2009, utility taxes of $130 million and $121 million, respectively, are included in revenues and expenses for PECO.

(c)		The intersegment profit associated with Generation’s sale of RECs to ComEd and AECs to PECO is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. See Note 3 — Regulatory Issues for additional information on RECs and AECs.


	Mid-Atlantic		Midwest		South			Other(b)			Generation
Total revenues(a):
2010	$	1,531	$	2,734	$	298		$	210		$	4,773
2009		1,687		2,793		346			153			4,979
Revenues net of purchased power and fuel expense:
2010	$	1,197	$	2,010	$	(91	)	$	160		$	3,276
2009		1,377		2,090		(58	)		(5	)		3,404


(a)		Includes all sales to third parties and affiliated sales to ComEd and PECO. For the six months ended June 30, 2010 and 2009, there were no transactions among Generation’s reportable segments which would result in intersegment revenue for Generation.

(b)		Includes retail gas, proprietary trading, other revenue and mark-to-market activities as well as amounts paid related to the Illinois Settlement Legislation.

Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Basis of Presentation (Details) - USD ($) $ in Millions	Jun. 30, 2010	Jun. 30, 2010	Dec. 31, 1998	Dec. 31, 2009
Consolidation Percentages Detail Tagging [Abstract]
Percentage ownership of consolidated subsidiaries	100.00%	100.00%
Percentage ownership of Exelon SHC, LLC	1.00%	1.00%
Percentage ownership of ComEd's common stock	99.00%	99.00%
Percentage ownership of PECO's common stock	100.00%	100.00%
Third-party interest in ComEd - exclusive upper bound	$ 1	$ 1
Controlling ownership interest percentage	50.00%	50.00%
Variable Interest Entities Detail Tagging [Abstract]
Restricted cash and cash equivalents of variable interest entity	$ 426	$ 426		$ 0
Long-term debt of variable interest entity due within one year	$ 404	$ 404		0
EXELON GENERATION CO LLC
Consolidation Percentages Detail Tagging [Abstract]
Percentage ownership of Exelon SHC, LLC	99.00%	99.00%
PECO ENERGY CO
Variable Interest Entities Detail Tagging [Abstract]
Amount of PECO's stranded costs authorized to be recovered by the PAPUC			$ 5,000
Initial capital contribution in PETT			$ 25
Pre-tax loss related to PETT	$ 5	$ 12
Interest expense on PETT's transition bonds	7	18
Restricted cash and cash equivalents of variable interest entity	426	426		0
Long-term debt of variable interest entity due within one year	$ 404	$ 404		$ 0

Regulatory Matters (Details)
$ in Millions

3 Months Ended

6 Months Ended

12 Months Ended

24 Months Ended

60 Months Ended

120 Months Ended

Jun. 30, 2010

USD ($)

Mar. 31, 2010

USD ($)

Jun. 30, 2009

USD ($)

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

May 31, 2012

May 31, 2011

USD ($)

May 31, 2010

USD ($)

Dec. 31, 2009

USD ($)

Dec. 31, 2015

Dec. 31, 2020

May 31, 2013

Apr. 12, 2010

USD ($)

Feb. 11, 2010

USD ($)

Nov. 25, 2009

USD ($)

$ 4,380.0

$ 4,872.0

Total regulatory assets

4,396.0

4,928.0

Total regulatory liabilities

3,344.0

3,492.0

3,395.0

3,525.0

Operating and Maintenance for Regulatory Required Programs

Energy efficiency and demand response programs

33.0

$ 13.0

58.0

$ 23.0

Purchased power administrative costs

1.0

2.0

Consumer education program

1.0

Total operating and maintenance for regulatory required programs

34.0

14.0

61.0

25.0

Illinois Settlement Agreement

Overall rate relief contribution

1,000.0

Illinois Electric Distribution Rate Case

One-time benefit to reverse prior charges and record regulatory assets

39.0

Nuclear Decommissioning [Member]

^[1]

2,069.0

2,229.0

Removal Costs [Member]

Refund of PURTA Taxes [Member]

1,229.0

1,212.0

4.0

Deferred Taxes [Member]

Energy Efficiency and Demand Response Programs [Member]

30.0

Other Regulatory Liabilities [Member]

41.0

15.0

Over Recovered Energy And Transmission Costs [Member]

1.0

2.0

Current regulatory liability

51.0

33.0

AMI Expenses[Member]

Recoverable Accelerated Depreciation [Member]

3.0

Competitive Transition Charge [Member]

3.0

Pension and Other Postretirement Benefits [Member]

438.0

883.0

Deferred Income Taxes [Member]

2,540.0

2,634.0

851.0

842.0

Debt Costs [Member]

131.0

144.0

Severance [Member]

Asset Retirement Obligations [Member]

84.0

95.0

MGP Remediation Costs [Member]

66.0

65.0

RTO Start-Up Costs [Member]

136.0

143.0

Under-Recovered Uncollectible Accounts [Member]

11.0

12.0

Financial Swap with Generation [Member]

49.0

0.0

DSP Program Electric Procurement Contracts [Member]

0.0

2.0

Other Regulatory Assets [Member]

2.0

Under Recovered Energy And Transmission Costs [Member]

60.0

47.0

DSP Program costs [Member]

14.0

56.0

6.0

5.0

Illinois settlement contributions

Illinois Settlement Agreement

7.0

30.0

9.0

63.0

Total remaining Illinois settlement costs

12.0

Remaining Illinois settlement costs to ComEd

6.0

Remaining Illinois settlement costs to other Illinois utilities

6.0

1,082.0

1,096.0

397.0

358.0

Total regulatory assets

1,479.0

1,454.0

Total regulatory liabilities

3,045.0

3,145.0

3,058.0

3,156.0

Operating and Maintenance for Regulatory Required Programs

Energy efficiency and demand response programs

^[2]

20.0

13.0

38.0

23.0

Purchased power administrative costs

1.0

2.0

Total operating and maintenance for regulatory required programs

21.0

14.0

^[3]

40.0

25.0

Illinois Settlement Agreement

Illinois settlement contributions

$ 2.0

1.0

$ 3.0

Illinois Procurement Proceedings

Percentage of expected energy requirements purchased through request for proposal process

6.00%

25.00%

Illinois Electric Distribution Rate Case

One-time benefit to reverse prior charges and record regulatory assets

39.0

Requested increase in electric revenues

396.0

$ 396.0

Expected increase in residential customer bills

7.00%

ComEd's proposed increase to net distribution revenue requirement related to uncollectable account expense

$ 22.0

Illinois Legislation for Recovery of Uncollectible Accounts

Under-collected uncollectible accounts regulatory asset

70.0

One-time operating and maintenance expense charge

$ 10.0

Annual Transmission Formula Rate Update

Gross transmission revenue requirement

$ 430.0

Transmission revenue true up

14.0

Net transmission revenue requirement

$ 416.0

$ 440.0

Weighted average debt and equity return on transmission rate base

9.27%

9.43%

Rate of return on common equity

11.50%

Cap on common equity component used to compute return for formula transmission rate

56.00%

55.00%

COMMONWEALTH EDISON CO | Nuclear Decommissioning [Member]

COMMONWEALTH EDISON CO | Removal Costs [Member]

^[1]

1,797.0

$ 1,797.0

1,918.0

COMMONWEALTH EDISON CO | Refund of PURTA Taxes [Member]

1,229.0

1,212.0

COMMONWEALTH EDISON CO | Deferred Taxes [Member]

0.0

COMMONWEALTH EDISON CO | Energy Efficiency and Demand Response Programs [Member]

0.0

COMMONWEALTH EDISON CO | Other Regulatory Liabilities [Member]

19.0

15.0

COMMONWEALTH EDISON CO | Over Recovered Energy And Transmission Costs [Member]

0.0

Current regulatory liability

13.0

11.0

COMMONWEALTH EDISON CO | AMI Expenses[Member]

COMMONWEALTH EDISON CO | Recoverable Accelerated Depreciation [Member]

0.0

COMMONWEALTH EDISON CO | Competitive Transition Charge [Member]

0.0

COMMONWEALTH EDISON CO | Pension and Other Postretirement Benefits [Member]

0.0

COMMONWEALTH EDISON CO | Deferred Income Taxes [Member]

0.0

COMMONWEALTH EDISON CO | Debt Costs [Member]

21.0

20.0

COMMONWEALTH EDISON CO | Severance [Member]

114.0

125.0

COMMONWEALTH EDISON CO | Asset Retirement Obligations [Member]

84.0

95.0

COMMONWEALTH EDISON CO | MGP Remediation Costs [Member]

50.0

49.0

COMMONWEALTH EDISON CO | RTO Start-Up Costs [Member]

97.0

103.0

COMMONWEALTH EDISON CO | Under-Recovered Uncollectible Accounts [Member]

11.0

12.0

COMMONWEALTH EDISON CO | Financial Swap with Generation [Member]

49.0

627.0

669.0

COMMONWEALTH EDISON CO | DSP Program Electric Procurement Contracts [Member]

383.0

302.0

0.0

COMMONWEALTH EDISON CO | Other Regulatory Assets [Member]

0.0

COMMONWEALTH EDISON CO | Under Recovered Energy And Transmission Costs [Member]

29.0

23.0

COMMONWEALTH EDISON CO | DSP Program costs [Member]

14.0

56.0

0.0

1,403.0

1,834.0

Total regulatory assets

1,408.0

1,834.0

Total regulatory liabilities

299.0

317.0

337.0

339.0

Operating and Maintenance for Regulatory Required Programs

Energy efficiency and demand response programs

13.0

20.0

Consumer education program

^[4]

1.0

Total operating and maintenance for regulatory required programs

13.0

$ 21.0

Illinois Electric Distribution Rate Case

Requested increase in electric revenues

316.0

Requested increase in gas revenues

$ 44.0

Requested rate of return on common equity

11.75%

Expected increase in electric delivery rates

6.94%

Expected increase in gas delivery rates

5.28%

Pennsylvania Procurement Proceedings

Additional competitive procurements over the term of default service provider program

Percentage of residential full requirements covered by contract

72.00%

Percentage of small commercial class requirements covered by contracts

60.00%

Percentage of medium commercial class requirements covered by contracts

58.00%

Size of block contract for residential service

260

Percentage of large commercial and industrial full requirements covered by contract

100.00%

Smart Meter and Smart Grid Investments

Estimated number of smart meters to be installed

1.6

Smart grid investment grant amount

$ 200.0

Initial number of smart meters deployed - first 3 years

600,000

Estimated investment in smart grid

$ 100.0

400.0

Amount of smart grid investment grant budget allocated to sub-recipients

7.0

Estimated total spend on smart grid and smart meter infrastructure

$ 650.0

Smart meter procurement plan estimated costs

$ 550.0

Energy Efficiency Program

Total approved amount under energy efficiency and conservation / demand plan

$ 330.0

Alternative Energy Portfolio Standards

Total alternative energy credits purchased annually

452,000

Solar tier 1 alternative energy credits purchased annually

8,000

PECO ENERGY CO | Nuclear Decommissioning [Member]

PECO ENERGY CO | Removal Costs [Member]

^[1]

272.0

$ 272.0

311.0

PECO ENERGY CO | Refund of PURTA Taxes [Member]

0.0

PECO ENERGY CO | Deferred Taxes [Member]

4.0

PECO ENERGY CO | Energy Efficiency and Demand Response Programs [Member]

0.0

PECO ENERGY CO | Other Regulatory Liabilities [Member]

22.0

0.0

PECO ENERGY CO | Over Recovered Energy And Transmission Costs [Member]

1.0

2.0

Current regulatory liability

38.0

22.0

PECO ENERGY CO | AMI Expenses[Member]

PECO ENERGY CO | Recoverable Accelerated Depreciation [Member]

3.0

PECO ENERGY CO | Competitive Transition Charge [Member]

3.0

PECO ENERGY CO | Pension and Other Postretirement Benefits [Member]

438.0

883.0

PECO ENERGY CO | Deferred Income Taxes [Member]

16.0

19.0

PECO ENERGY CO | Debt Costs [Member]

830.0

822.0

PECO ENERGY CO | Severance [Member]

17.0

19.0

PECO ENERGY CO | Asset Retirement Obligations [Member]

0.0

^[5]

PECO ENERGY CO | MGP Remediation Costs [Member]

16.0

PECO ENERGY CO | RTO Start-Up Costs [Member]

39.0

40.0

PECO ENERGY CO | Under-Recovered Uncollectible Accounts [Member]

0.0

PECO ENERGY CO | Financial Swap with Generation [Member]

0.0

0.0

PECO ENERGY CO | DSP Program Electric Procurement Contracts [Member]

0.0

4.0

^[6]

PECO ENERGY CO | Other Regulatory Assets [Member]

5.0

PECO ENERGY CO | Under Recovered Energy And Transmission Costs [Member]

31.0

26.0

PECO ENERGY CO | DSP Program costs [Member]

0.0

Fair Value Assets And Liabilities Measured On Recurring Basis

$ 6.0

$ 5.0

[1]	These amounts represent estimated future nuclear decommissioning costs that are less than the associated NDT fund assets. These regulatory liabilities have an equal and offsetting noncurrent receivable from affiliate at ComEd and PECO, and a noncurrent payable to affiliate recorded at Generation equal to the total regulatory liability at Exelon, ComEd and PECO. See Note 10 - Nuclear Decommissioning for additional information on the NDT fund activity.
[2]	As a result of the Illinois Settlement Legislation, Illinois utilities are required to provide energy efficiency and demand response programs.
[3]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[4]	In 2009, the PAPUC authorized PECO to collect a surcharge to recover expenditures associated with PECO's approved consumer education plan related to the transition to competitive energy market prices.
[5]	During the second quarter, ComEd recorded a reduction of $25 million to taxes other than income to reflect management's estimate of future refunds for the 2008, 2009 and 2010 tax years associated with Illinois' utility distribution tax based on an analysis of past refunds and interpretations of the Illinois Public Utility Act.
[6]	Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 - Basis of Presentation for additional information on the VIE.

Fair Value of Financial Assets and Liabilities (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2009

^[1]

$ 1,455

$ 1,845

^[2],[3]

804

(70)

(82)

(2)

8,933

^[4]

8,933

^[4]

9,283

(132)

(84)

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

8,801

9,199

^[4]

$ 1,417

(46)

$ 1,324

^[4]

(60)

(11)

^[4]

(2)

^[4]

^[4]

182

(2)

^[4]

^[5]

(8)

^[4]

334

^[4]

^[4]

(2)

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

1,689

^[4]

(31)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

^[4]

(31)

Fair Value of Financial Assets and Liabilities (Textuals)

Net assets (liabilities) excluded from nuclear decommissioning trust fund investments

102

Cash surrender value of life insurance investments excluded from Rabbi Trust investments

Gain (loss) reclassified to results of operating due to the settlement of derivative contracts

(12)

(30)

Proceeds from agreement under servicing liability

225

Operating Revenue [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(21)

(42)

Purchased Power [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

(21)

(9)

(7)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(20)

(10)

(6)

(21)

(9)

(7)

Fuel [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

(12)

(64)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(2)

(53)

(12)

(64)

Other, net [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

Nuclear Decommissioning Trust Fund Investments Level Three Asset [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

1,371

1,220

^[4]

^[4]

^[4]

183

^[4]

^[4]

334

^[4]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

^[4]

1,679

^[4]

1,679

^[4]

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

^[4]

Derivative Financial Instruments Assets Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

^[4]

(44)

106

(33)

^[6]

^[4],[7]

(101)

^[6]

(11)

^[4],[8]

(2)

^[9]

^[4],[8]

^[9]

^[4]

(1)

(2)

^[4]

(1)

(8)

^[4]

^[4]

^[4]

(2)

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

^[4]

(21)

^[4]

(71)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

^[4]

(21)

^[4]

(71)

Servicing Liability Level Three Liability [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

(2)

^[4]

^[4],[5]

^[4],[5]

^[4]

^[4]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

(2)

^[4]

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

^[4]

Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

126

^[4]

126

^[4]

122

^[10]

1,414

1,528

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[11]

1,920

2,086

808

630

Debt securities issued by states of the United States and political subdivisions of the states

440

454

719

710

761

887

Residential mortgage-backed securities (non-agency)

125

Nuclear decommissioning trust fund investments subtotal

^[12]

6,396

6,593

Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[13]

Derivative Financial Instruments, Assets [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

977

1,927

Effect of netting and allocation of collateral received/paid

334

^[14]

(2,193)

Derivative Financial Instruments, Assets [Member] | Nuclear Decommissioning Trust Fund Investments Level Three Asset [Member]

^[3]

1,045

Derivative Financial Instruments, Assets [Member] | Servicing Liability Level Three Liability [Member]

^[4]

Derivative Financial Instruments, Liabilities [Member]

^[4]

Fair Value Assets And Liabilities Measured On Recurring Basis

(82)

(980)

Effect of netting and allocation of collateral received/paid

(295)

^[2]

(1,295)

Fair Value Inputs Level 1 [Member]

^[3]

(62)

Fair Value Assets And Liabilities Measured On Recurring Basis

^[1]

1,455

1,845

^[15]

3,658

3,923

^[5]

Fair Value of Financial Assets and Liabilities (Textuals)

3,658

3,923

Collateral received from counterparties, net of collateral paid to counterparties

Fair Value Inputs Level 1 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[10]

1,414

1,528

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[11]

702

511

Debt securities issued by states of the United States and political subdivisions of the states

Residential mortgage-backed securities (non-agency)

Nuclear decommissioning trust fund investments subtotal

^[12]

2,169

2,041

Fair Value Inputs Level 1 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[13]

Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Assets [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

Effect of netting and allocation of collateral received/paid

^[14]

(6)

Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[3]

(3)

Fair Value Assets And Liabilities Measured On Recurring Basis

(3)

Effect of netting and allocation of collateral received/paid

^[2]

(3)

Fair Value Inputs Level 2 [Member]

^[3]

(4)

^[2]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[1]

(70)

(82)

5,184

^[16]

5,184

^[16]

5,404

(109)

(82)

Fair Value of Financial Assets and Liabilities (Textuals)

5,075

5,322

Collateral received from counterparties, net of collateral paid to counterparties

884

941

Fair Value Inputs Level 2 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

120

^[10]

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[11]

1,920

2,086

106

119

Debt securities issued by states of the United States and political subdivisions of the states

440

454

719

710

761

887

Residential mortgage-backed securities (non-agency)

125

Nuclear decommissioning trust fund investments subtotal

^[12]

4,226

4,552

Fair Value Inputs Level 2 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[13]

Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Assets [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

973

1,852

Effect of netting and allocation of collateral received/paid

287

^[14]

(2,154)

Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[3]

958

852

^[2]

Fair Value Assets And Liabilities Measured On Recurring Basis

(79)

(948)

Effect of netting and allocation of collateral received/paid

(282)

^[2]

(1,270)

Fair Value Inputs Level 3 [Member]

^[3]

(39)

Fair Value Assets And Liabilities Measured On Recurring Basis

^[1]

(2)

(44)

(23)

(2)

Fair Value of Financial Assets and Liabilities (Textuals)

(46)

Collateral received from counterparties, net of collateral paid to counterparties

Fair Value Inputs Level 3 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[10]

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[11]

Debt securities issued by states of the United States and political subdivisions of the states

Residential mortgage-backed securities (non-agency)

Nuclear decommissioning trust fund investments subtotal

^[12]

Fair Value Inputs Level 3 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[13]

Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Assets [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

Effect of netting and allocation of collateral received/paid

^[14]

(33)

Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[3]

Fair Value Assets And Liabilities Measured On Recurring Basis

(3)

(29)

Effect of netting and allocation of collateral received/paid

(13)

^[2]

(22)

Carrying Reported Amount Fair Value Disclosure [Member]

^[3]

(23)

(44)

^[2],[17]

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

11,026

11,634

Long-term debt of variable interest entity due within one year

^[18]

404

^[18]

415

390

1,018

1,017

Estimate Of Fair Value Fair Value Disclosure [Member]

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

12,077

12,223

Long-term debt of variable interest entity due within one year

^[18]

408

^[18]

426

332

325

864

832

Fair Value Assets And Liabilities Measured On Recurring Basis

^[19]

790

^[4]

790

^[4]

1,040

(19)

(23)

9,235

9,406

(71)

(23)

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

9,164

9,383

1,279

2,601

931

1,782

^[5]

(60)

(237)

^[5]

(146)

^[5]

592

Included in noncurrent payables to affiliates

^[5]

(8)

183

334

^[5]

^[5]

(2)

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

1,087

2,730

1,087

2,730

(31)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(31)

Fair Value of Financial Assets and Liabilities (Textuals)

Net assets (liabilities) excluded from nuclear decommissioning trust fund investments

102

Cash surrender value of life insurance investments excluded from Rabbi Trust investments

Fair value block contract current asset

Fair value block contract noncurrent asset

Fair value swap contract current asset

383

302

Fair value swap contract noncurrent asset

627

669

Gain (loss) reclassified to results of operating due to the settlement of derivative contracts

(12)

(30)

Increase (decrease) in fair value related to the swap contract

(121)

(85)

199

667

Realized gains (losses) related to swap contract

104

160

EXELON GENERATION CO LLC | Operating Revenue [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(21)

(42)

EXELON GENERATION CO LLC | Purchased Power [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

(21)

(9)

(7)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(20)

(10)

(6)

(21)

(9)

(7)

EXELON GENERATION CO LLC | Fuel [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

(12)

(64)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(2)

(53)

(12)

(64)

EXELON GENERATION CO LLC | Other, net [Member]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

EXELON GENERATION CO LLC | Nuclear Decommissioning Trust Fund Investments Level Three Asset [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

1,371

1,220

^[5]

^[5]

Included in noncurrent payables to affiliates

^[5]

183

334

^[5]

^[5]

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

1,679

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

EXELON GENERATION CO LLC | Derivative Financial Instruments Assets Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

1,279

1,230

931

562

(33)

^[20]

^[5],[15]

(101)

^[20]

(237)

^[5],[21]

(146)

^[22]

^[5],[23]

592

^[22]

Included in noncurrent payables to affiliates

^[5]

(8)

^[5]

^[5]

^[24]

(2)

The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities

1,086

1,051

1,086

1,051

(21)

(71)

Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings

Change in the unrealized gains (losses) relating to assets and liabilities held

(21)

(71)

Fair Value of Financial Assets and Liabilities (Textuals)

Increase (decrease) in fair value related to block contracts

(1)

EXELON GENERATION CO LLC | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

126

^[24]

126

^[24]

122

^[25]

1,414

1,528

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[26]

1,920

2,086

808

630

Debt securities issued by states of the United States and political subdivisions of the states

440

^[4]

440

^[4]

454

719

^[21]

719

^[21]

710

761

887

Residential mortgage-backed securities (non-agency)

125

Nuclear decommissioning trust fund investments subtotal

^[27]

6,396

6,593

EXELON GENERATION CO LLC | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

EXELON GENERATION CO LLC | Derivative Financial Instruments, Assets [Member]

^[28],[29]

Fair Value Assets And Liabilities Measured On Recurring Basis

1,992

1,912

Effect of netting and allocation of collateral received/paid

334

^[14]

(2,193)

EXELON GENERATION CO LLC | Derivative Financial Instruments, Liabilities [Member]

^[30]

2,045

1,769

^[14]

Fair Value Assets And Liabilities Measured On Recurring Basis

(76)

(976)

Effect of netting and allocation of collateral received/paid

(295)

^[14]

(1,295)

EXELON GENERATION CO LLC | Fair Value Inputs Level 1 [Member]

(52)

Fair Value Assets And Liabilities Measured On Recurring Basis

^[19]

790

1,040

2,960

3,081

Fair Value of Financial Assets and Liabilities (Textuals)

2,960

3,081

Collateral received from counterparties, net of collateral paid to counterparties

EXELON GENERATION CO LLC | Fair Value Inputs Level 1 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[25]

1,414

1,528

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[26]

702

511

Debt securities issued by states of the United States and political subdivisions of the states

Residential mortgage-backed securities (non-agency)

Nuclear decommissioning trust fund investments subtotal

^[27]

2,169

2,041

EXELON GENERATION CO LLC | Fair Value Inputs Level 1 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

EXELON GENERATION CO LLC | Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Assets [Member]

^[28],[29]

Fair Value Assets And Liabilities Measured On Recurring Basis

Effect of netting and allocation of collateral received/paid

^[14]

(6)

EXELON GENERATION CO LLC | Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[30]

(3)

(4)

^[14]

Fair Value Assets And Liabilities Measured On Recurring Basis

(3)

Effect of netting and allocation of collateral received/paid

^[14]

(3)

EXELON GENERATION CO LLC | Fair Value Inputs Level 2 [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[19]

(19)

(23)

5,169

5,394

(52)

(23)

Fair Value of Financial Assets and Liabilities (Textuals)

5,117

5,371

Collateral received from counterparties, net of collateral paid to counterparties

884

941

EXELON GENERATION CO LLC | Fair Value Inputs Level 2 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

120

^[25]

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[26]

1,920

^[8]

1,920

^[8]

2,086

106

119

Debt securities issued by states of the United States and political subdivisions of the states

440

454

719

710

761

887

Residential mortgage-backed securities (non-agency)

125

Nuclear decommissioning trust fund investments subtotal

^[27]

4,226

4,552

EXELON GENERATION CO LLC | Fair Value Inputs Level 2 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

EXELON GENERATION CO LLC | Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Assets [Member]

^[28],[29]

Fair Value Assets And Liabilities Measured On Recurring Basis

973

1,837

Effect of netting and allocation of collateral received/paid

287

^[14]

(2,154)

EXELON GENERATION CO LLC | Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[30]

943

842

^[14],[31]

Fair Value Assets And Liabilities Measured On Recurring Basis

(73)

(948)

Effect of netting and allocation of collateral received/paid

(282)

^[14]

(1,270)

EXELON GENERATION CO LLC | Fair Value Inputs Level 3 [Member]

(33)

Fair Value Assets And Liabilities Measured On Recurring Basis

^[19]

1,106

931

(19)

Fair Value of Financial Assets and Liabilities (Textuals)

1,087

931

Collateral received from counterparties, net of collateral paid to counterparties

EXELON GENERATION CO LLC | Fair Value Inputs Level 3 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[25]

Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies

^[26]

Debt securities issued by states of the United States and political subdivisions of the states

Residential mortgage-backed securities (non-agency)

Nuclear decommissioning trust fund investments subtotal

^[27]

EXELON GENERATION CO LLC | Fair Value Inputs Level 3 [Member] | Rabbi Trust Investments [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

EXELON GENERATION CO LLC | Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Assets [Member]

^[28],[29]

Fair Value Assets And Liabilities Measured On Recurring Basis

1,019

Effect of netting and allocation of collateral received/paid

^[14]

(33)

EXELON GENERATION CO LLC | Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[30]

1,105

931

^[14]

Fair Value Assets And Liabilities Measured On Recurring Basis

(3)

(25)

Effect of netting and allocation of collateral received/paid

(13)

^[14]

(22)

EXELON GENERATION CO LLC | Carrying Reported Amount Fair Value Disclosure [Member]

(19)

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

2,779

2,993

EXELON GENERATION CO LLC | Estimate Of Fair Value Fair Value Disclosure [Member]

1,018

^[4]

1,018

^[4]

1,017

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

3,021

3,132

864

832

Fair Value Assets And Liabilities Measured On Recurring Basis

^[32]

(7)

(8)

(1,023)

(979)

Fair Value of Financial Assets and Liabilities (Textuals)

(992)

(926)

Increase (decrease) in fair value related to the swap contract

121

(199)

(667)

Realized gains (losses) related to swap contract

104

160

Fair value swap contract current liability

383

302

Fair value swap contract noncurrent liability

627

669

COMMONWEALTH EDISON CO | Cash Flow Hedges [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Other Derivatives [Member]

^[33]

(6)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Derivative Financial Instruments Assets Liabilities [Member]

^[21]

(1,010)

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

(1,235)

(1,182)

(971)

(456)

225

^[34]

145

^[35]

(39)

^[34]

(581)

^[35]

COMMONWEALTH EDISON CO | Rabbi Trust Investments [Member]

(1,010)

(1,037)

(1,010)

(1,037)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Derivative Financial Instruments, Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 1 [Member]

(1,016)

(971)

^[21]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[32]

COMMONWEALTH EDISON CO | Fair Value Inputs Level 1 [Member] | Cash Flow Hedges [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 1 [Member] | Other Derivatives [Member]

^[33]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 1 [Member] | Rabbi Trust Investments [Member]

^[21]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 2 [Member]

^[21]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[32]

(7)

(8)

(13)

(8)

COMMONWEALTH EDISON CO | Fair Value Inputs Level 2 [Member] | Cash Flow Hedges [Member]

(13)

(8)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 2 [Member] | Other Derivatives [Member]

^[33]

(6)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 2 [Member] | Rabbi Trust Investments [Member]

^[21]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 3 [Member]

(6)

^[21]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[32]

^[4]

(1,010)

(971)

COMMONWEALTH EDISON CO | Fair Value Inputs Level 3 [Member] | Cash Flow Hedges [Member]

(1,010)

(971)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 3 [Member] | Other Derivatives [Member]

^[33]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 3 [Member] | Rabbi Trust Investments [Member]

^[21]

(1,010)

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis

COMMONWEALTH EDISON CO | Carrying Reported Amount Fair Value Disclosure [Member]

(1,010)

(971)

^[21]

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

4,712

4,711

COMMONWEALTH EDISON CO | Estimate Of Fair Value Fair Value Disclosure [Member]

206

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

5,260

5,062

173

167

Fair Value Assets And Liabilities Measured On Recurring Basis

^[36]

612

281

(22)

(25)

(2)

619

288

(31)

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

588

257

(2)

(6)

(2)

(2)

(5)

(2)

Fair Value of Financial Assets and Liabilities (Textuals)

(9)

(4)

(9)

(4)

Cash surrender value of life insurance investments excluded from Rabbi Trust investments

Fair value block contract current liabilities

Fair value block contract noncurrent liabilities

Increase (decrease) in fair value related to block contracts

(3)

Fair value block contract current liability - Total

Fair value block contract noncurrent liability - Total

Proceeds from agreement under servicing liability

225

PECO ENERGY CO | Derivative Financial Instruments Assets Liabilities [Member]

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

(11)

(4)

^[37]

(2)

(5)

^[37]

(2)

PECO ENERGY CO | Servicing Liability Level Three Liability [Member]

(9)

(2)

(9)

(2)

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation

(2)

^[38]

PECO ENERGY CO | Rabbi Trust Investments [Member]

$ (2)

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Derivative Financial Instruments, Liabilities [Member]

^[39],[40]

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 1 [Member]

^[41]

(9)

(4)

Fair Value Assets And Liabilities Measured On Recurring Basis

^[36]

612

281

619

288

PECO ENERGY CO | Fair Value Inputs Level 1 [Member] | Rabbi Trust Investments [Member]

619

288

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[39],[40]

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 2 [Member]

^[41]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[36]

(22)

(25)

(22)

(25)

PECO ENERGY CO | Fair Value Inputs Level 2 [Member] | Rabbi Trust Investments [Member]

(22)

(25)

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[39],[40]

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 3 [Member]

^[41]

Fair Value Assets And Liabilities Measured On Recurring Basis

^[36]

(2)

(9)

(6)

PECO ENERGY CO | Fair Value Inputs Level 3 [Member] | Rabbi Trust Investments [Member]

(9)

(6)

Fair Value Assets And Liabilities Measured On Recurring Basis

PECO ENERGY CO | Fair Value Inputs Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

^[39],[40]

Fair Value Assets And Liabilities Measured On Recurring Basis

Fair Value of Financial Assets and Liabilities (Textuals)

^[41]

(9)

Fair value swap contract noncurrent asset

^[41]

(4)

PECO ENERGY CO | Carrying Reported Amount Fair Value Disclosure [Member]

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

2,221

Long-term debt of variable interest entity due within one year

^[42]

404

^[42]

415

184

PECO ENERGY CO | Estimate Of Fair Value Fair Value Disclosure [Member]

Fair Value of Financial Liabilities Recorded at the Carrying Amount

Long-term debt (including amounts due within on year)

2,461

2,346

Long-term debt of variable interest entity due within one year

^[42]

408

^[42]

426

159

158

Accounts Receivable Agreement [Abstract]

$ 70

$ 63

[1]	Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 - Basis of Presentation for additional information on the VIE.
[2]	Includes collateral postings received from counterparties. Collateral received from counterparties totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2009.
[3]	The Level 3 balance does not include current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation's financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010 and a noncurrent asset of $2 million at December 31, 2009, respectively, related to the fair value of Generation's block contracts with PECO, which eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[4]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[5]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[6]	Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.
[7]	Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.
[8]	Excludes increases/(decreases) in the fair value of ($121) million and $199 million and realized losses due to settlements of $104 million and $160 million associated with Generation's financial swap contract with ComEd and ($1) million and $3 million of changes in fair value of Generation's block contracts with PECO for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[9]	Excludes increases/(decreases) in fair value of $85 million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation's financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All amounts eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[10]	Generation's NDT funds hold equity portfolios whose performance is benchmarked against the S and P 500 Index, Russell 3000 Index or Morgan Stanley Capital International Europe, Australasia and Far East (EAFE) Index.
[11]	Generation's NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S and P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.
[12]	Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.
[13]	Excludes $22 million and $23 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009, respectively.
[14]	Includes collateral postings received from counterparties. Collateral received from counterparties totaled $3 million, $884 million and $11 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 30, 2010. Collateral received from counterparties, net of collateral paid to counterparties, totaled $3 million, $941 million and $3 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 20098
[15]	Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.
[16]	During the second quarter, ComEd recorded a reduction of $25 million to taxes other than income to reflect management's estimate of future refunds for the 2008, 2009 and 2010 tax years associated with Illinois' utility distribution tax based on an analysis of past refunds and interpretations of the Illinois Public Utility Act.
[17]	In 2009, the PAPUC authorized PECO to collect a surcharge to recover expenditures associated with PECO's approved consumer education plan related to the transition to competitive energy market prices.
[18]	On January 1, 2010, PETT was consolidated in Exelon's Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 - Basis of Presentation for additional information.
[19]	Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.
[20]	Includes the reclassification of $12 million and $30 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2009, respectively.
[21]	The Level 3 balance is comprised of the current and noncurrent liability of $383 million and $627 million at June 30, 2010, respectively, and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of ComEd's financial swap contract with Generation, which eliminates upon consolidation in Exelon's Consolidated Financial Statements.
[22]	Includes increases/(decreases) in fair value of $85 million and $667 million and realized losses due to settlements of $60 million and $86 million associated with Generation's financial swap contract with ComEd for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[23]	Excludes increases/(decreases) in fair value of $645 million and $320 million and realized gains due to settlements of $31 million and $38 million associated with Generation's financial swap contract with ComEd for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[24]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[25]	Generation's NDT funds hold equity portfolios whose performance is benchmarked against the S and P 500 Index, Russell 3000 Index or Morgan Stanley Capital International EAFE Index.
[26]	Generation's NDT funds own commingled funds that invest in both equity and fixed income securities. The commingled funds that invest in equity securities seek to track the performance of the S and P 500 Index, Morgan Stanley Capital International EAFE Index and Russell 3000 Index. The commingled funds that hold fixed income securities invest primarily in a diversified portfolio of high grade money market instruments and other short-term fixed income securities.
[27]	Excludes net assets of $102 million and $76 million at June 30, 2010 and December 31, 2009, respectively. These items consist of receivables related to pending securities sales net of cash, interest receivables and payables related to pending securities purchases.
[28]	Excludes $7 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.
[29]	The mutual funds held by the Rabbi trusts that are invested in common stock of S and P 500 companies and Pennsylvania municipal bonds are primarily rated as investment grade.
[30]	The Level 3 balance includes current and noncurrent assets for Generation of $383 million and $627 million at June 30, 2010 and $302 million and $669 million at December 31, 2009, respectively, related to the fair value of Generation's financial swap contract with ComEd; and current and noncurrent assets of $3 million and $2 million at June 30, 2010, respectively, and a noncurrent asset of $2 million at December 31, 2009, related to the fair value of Generation's block contracts with PECO. All of the mark-to-market balances Generation carries associated with the financial swap contract with ComEd and the block contracts with PECO eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[31]	Includes accumulated amortization of nuclear fuel in the reactor core of $1,384 million.
[32]	Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.
[33]	Cash flow hedges relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[34]	Includes increases/(decreases) in fair value of $121 million and $199 million and realized gains due to settlements of $104 million and $160 million associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[35]	Includes increases/(decreases) in fair value of $85 million and $667 million and realized gains due to settlements of $60 million and $86 million associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2009, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[36]	Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value. Includes restricted cash equivalents of VIE at June 30, 2010. See Note 1 - Basis of Presentation for additional information on the VIE.
[37]	Includes increases/(decreases) in fair value of $1 million and $3 associated with PECO's block contract with Generation for the three and six months ended June 30, 2010, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
[38]	The servicing liability related to PECO's accounts receivable agreement was released in accordance with new guidance on accounting for transfers of financial assets that was adopted on January 1, 2010. See Note 5 - Debt and Credit Agreements for additional information.
[39]	Excludes $11 million and $12 million of the cash surrender value of life insurance investments at June 30, 2010 and December 31, 2009.
[40]	The mutual funds held by the Rabbi trusts invest in common stock of S and P 500 companies and Pennsylvania municipal bonds that are primarily rated as investment grade.
[41]	The Level 3 balance is comprised of the current and noncurrent liability of $5 million and $4 million at June 30, 2010, respectively, and the noncurrent liability of $4 million at December 31, 2009, related to the fair value of PECO's block contracts. These liability balances include a $3 million and $2 million current and noncurrent liability, respectively, at June 30, 2010, and a noncurrent liability of $2 million at December 31, 2009, related to the fair value of PECO's block contracts with Generation that eliminates upon consolidation in Exelon's Consolidated Financial Statements.
[42]	On January 1, 2010, PETT was consolidated in PECO's Consolidated Financial Statements in accordance with the new FASB authoritative guidance related to the consolidation of VIEs. See Note 1 - Basis of Presentation for additional information.

Debt and Credit Agreements (Details)
$ in Millions

6 Months Ended

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

Mar. 25, 2010

USD ($)

Dec. 31, 2009

USD ($)

Accounts receivable, pledged under accounts receivable agreement

$ 225

Short-term notes payable - accounts receivable agreement

225

$ 0

Gross accounts receivable pledged as collateral

(2)

$ 366

Long Term Debt Retirements [Member] | Senior Notes [Member]

Issuances and Retirements of Long-Term Debt [Abstract]

4.45%

Commercial Paper and Credit Facility Borrowings [Abstract]

$ 400

Exelon Corporate

^[1]

Aggregate bank commitments under unsecured revolving credit facilities

957

Commercial Paper and Credit Facility Borrowings [Abstract]

Aggregate bank commitments under unsecured revolving credit facilities

4,800

Additional Credit Facility Agreements [Abstract]

Credit facility agreements with minority and community banks

Letters of credit

Variable Rate Debt [Abstract]

Variable-rate long-term tax-exempt debt

$ 212

EXELON GENERATION CO LLC | Long Term Debt Issuances [Member] | Pollution Control Notes [Member]

Issuances and Retirements of Long-Term Debt [Abstract]

5.00%

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | York County Series 1993 A Tax Exempt Bonds [Member]

^[2]

$ 46

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Indiana County Series 2003 A Tax Exempt Bonds [Member]

$ 19

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Montgomery County Series 1996 A Tax Exempt Bonds [Member]

$ 17

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Montgomery County Series 1994 A Tax Exempt Bonds [Member]

$ 34

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Montgomery County Series 1994 B Tax Exempt Bonds [Member]

$ 83

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Salem Series Tax Exempt Bonds [Member]

$ 13

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Pollution Control Notes [Member]

$ 23

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Capital Lease Obligations [Member]

$ 46

Issuances and Retirements of Long-Term Debt [Abstract]

7.83%

EXELON GENERATION CO LLC | Long Term Debt Retirements [Member] | Delaware Series A Tax Exempt Bonds [Member]

$ 1

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

$ 24

Commercial Paper and Credit Facility Borrowings [Abstract]

Credit facility borrowings

289

155

Aggregate bank commitments under unsecured revolving credit facilities

1,000

Original unsecured revolving credit facility

$ 952

Basis points adders for prime-based borrowings

137.5

Basis points adders for LIBOR-based borrowings

237.5

Additional Credit Facility Agreements [Abstract]

Credit facility agreements with minority and community banks

Letters of credit

$ 26

COMMONWEALTH EDISON CO | Long Term Debt Issuances [Member] | First Mortgage Bonds 2021 [Member]

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Issuances [Member] | First Mortgage Bonds 2017 [Member]

^[2],[3]

$ 50

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Issuances [Member] | First Mortgage Bonds 2020 [Member]

^[2],[3]

$ 91

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Retirements [Member] | First Mortgage Bond [Member]

^[2],[3]

$ 50

Issuances and Retirements of Long-Term Debt [Abstract]

5.70%

COMMONWEALTH EDISON CO | Long Term Debt Retirements [Member] | First Mortgage Bonds 2021 [Member]

$ 16

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Retirements [Member] | First Mortgage Bonds 2017 [Member]

^[4]

$ 50

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Retirements [Member] | First Mortgage Bonds 2020 [Member]

^[4]

$ 91

Issuances and Retirements of Long-Term Debt [Abstract]

Variable

COMMONWEALTH EDISON CO | Long Term Debt Retirements [Member] | Sinking Fund Debentures [Member]

^[4]

$ 50

Issuances and Retirements of Long-Term Debt [Abstract]

4.75%

4.625%-4.75%

$ 1

Commercial Paper and Credit Facility Borrowings [Abstract]

Aggregate bank commitments under unsecured revolving credit facilities

574

Additional Credit Facility Agreements [Abstract]

Credit facility agreements with minority and community banks

Letters of credit

Accounts Receivable Agreement [Abstract]

Accounts receivable, pledged under accounts receivable agreement

225

Short-term notes payable - accounts receivable agreement

225

Gross accounts receivable pledged as collateral

$ (2)

$ 366

PECO ENERGY CO | Long Term Debt Issuances [Member] | First Mortgage Bonds [Member]

Issuances and Retirements of Long-Term Debt [Abstract]

5.00%

PECO ENERGY CO | Long Term Debt Retirements [Member] | PETT Transition Bonds 2010 [Member]

^[2]

$ 250

Issuances and Retirements of Long-Term Debt [Abstract]

6.52%

PECO ENERGY CO | Long Term Debt Retirements [Member] | PETT Transition Bonds [Member]

$ 402

$ 11

Issuances and Retirements of Long-Term Debt [Abstract]

7.65%

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

$ 319

[1]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[2]	Excludes unamortized bond discounts.
[3]	Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were remarketed in May 2009 following an earlier repurchase
[4]	Variable-rate tax-exempt bonds secured by First Mortgage Bonds, which were repurchased in May 2009 and subsequently remarketed.

Derivative Financial Instruments (Details)
$ in Millions

3 Months Ended

6 Months Ended

12 Months Ended

35 Months Ended

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

USD ($)

May 31, 2013

USD ($)

Mar. 31, 2010

USD ($)

Dec. 31, 2009

USD ($)

Mar. 31, 2009

USD ($)

Dec. 31, 2008

USD ($)

Mark-to-market derivative assets (noncurrent assets)

$ 418

$ 376

627

649

Mark-to-market derivative liabilities (current liabilities)

1,045

1,025

(54)

(198)

Mark-to-market derivative liabilities (noncurrent liabilities)

(8)

(23)

Total mark-to-market derivative net assets (liabilities)

(62)

(221)

983

804

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(47)

$ (173)

254

$ 40

(76)

(145)

(20)

Cost Of Capital Strategies [Abstract]

$ (123)

(170)

$ 109

Hypothetical increase in interest rates associated with variable-rate debt

10.00%

Pre-tax net income impact associated with a hypothetical 10% increase in interest rates - exclusive upper bound

$ 1

Interest Rate Risk - Fair Value Hedges [Abstract]

Notional amounts of fair value hedges outstanding related to interest rate swaps

100

Fair value assets

Cash Flow Hedge Activity Impact [Abstract]

Cash flow hedge activity impact on pre-tax net income based on reclassification adjustment from accumulated other comprehensive income

245

373

383

587

Change in cash flow hedge ineffectiveness

Swap Contract Collateral Posting Limit [Abstract]

Fair Value of Interest-Rate Swap in Asset Position

Master Netting Arrangements [Abstract]

Cash collateral received not offset against net derivative positions

Total Cash Flow Hedges [Member]

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Accumulated OCI derivative gain - Beginning Balance

934

1,110

551

585

$ 551

$ 525

Effective portion of changes in fair value

(262)

^[1]

205

^[1]

654

Accumulated OCI derivative gain - Ending Balance

525

890

525

890

Interest Expense Line Item [Member]

General Fair Value Hedge Information [Abstract]

Gain (Loss) on swaps

(6)

Gain (Loss) on borrowings

(5)

Operating Revenue [Member]

Proprietary Trading Activities [Abstract]

^[2]

(6)

(22)

(12)

(43)

Operating Revenue [Member] | Total Cash Flow Hedges [Member]

(19)

(40)

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Reclassifications from accumulated OCI to net income

(148)

(226)

(231)

(354)

Purchased Power [Member]

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(72)

(114)

181

142

(77)

(50)

(146)

(96)

Purchased Power [Member] | Total Cash Flow Hedges [Member]

(149)

(164)

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Ineffective portion recognized in income

Purchased Power [Member] | Cash Flow Hedges [Member]

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Ineffective portion recognized in income

Fuel [Member]

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(59)

(102)

(6)

(26)

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets with affiliate (current assets)

418

^[3]

418

^[3]

376

^[4]

386

^[3]

386

^[3]

302

^[4]

Mark-to-market derivative assets (noncurrent assets)

612

^[3]

612

^[3]

639

^[4]

Mark-to-market derivative assets with affiliate (noncurrent assets)

629

^[3]

629

^[3]

671

^[4]

Mark-to-market derivative liabilities (current liabilities)

2,045

^[3]

2,045

^[3]

1,988

^[4]

(46)

^[3]

(46)

^[3]

(198)

^[4]

Mark-to-market derivative liabilities (noncurrent liabilities)

(6)

^[3]

(6)

^[3]

(21)

^[4]

Total mark-to-market derivative net assets (liabilities)

(52)

^[3]

(52)

^[3]

(219)

^[4]

1,993

^[3]

1,993

^[3]

1,769

^[4]

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(47)

(173)

254

(76)

(145)

(20)

(123)

$ (170)

109

$ 20

Investor-owned utilities, marketers and power producers

Financial institutions

307

490

Coal

Total Counterparty Credit Risk Exposure

$ 886

Percent Of Expected Generation Being Hedged [Abstract]

Range of expected generation hedged

57%-60%

86%-89%

96%-99%

Swap Contract Volumes [Abstract]

Swap contract volumes

3,000

Proprietary Trading Volumes [Abstract]

Proprietary trading activities volume

889

2,003

1,808

4,334

Cost Of Capital Strategies [Abstract]

Pre-tax net income impact associated with a hypothetical 10% increase in interest rates - exclusive upper bound

$ 1

Fair Value Balances [Abstract]

Fair value swap contract noncurrent asset

627

669

Fair value swap contract current asset

383

302

Current assets collateral

586

502

Noncurrent assets collateral

309

376

Current liabilities collateral

Total cash collateral received net of cash collateral posted

898

974

Fair value block contract current asset

Fair value block contract noncurrent asset

Cash Flow Hedges [Abstract]

Net unrealized pre-tax gain (loss) on effective cash flow hedges

1,916

Net unrealized gain (loss) on effective cash flow hedges, net of tax

610

$ 624

610

$ 624

$ 746

585

$ 712

$ 275

Net unrealized pre-tax gain (loss) on effective cash flow hedges related to swap contract

1,010

Net unrealized gain (loss) related to fair value block contract, net of tax

Net gain (loss) related to effective portion of changes in fair value of five-year financial swap contract

(73)

(52)

122

401

(1)

Expected reclassification from accumulated other comprehensive income to results of operations

941

Expected reclassification from accumulated other comprehensive income to results of operations related to fair value swap contract

383

Net gains loss of reclassifications from accumulated OCI to net income related to the settlements of the five-year financial swap contract

Cash Flow Hedge Activity Impact [Abstract]

Cash flow hedge activity impact on pre-tax net income based on reclassification adjustment from accumulated other comprehensive income

349

543

434

674

Change in cash flow hedge ineffectiveness

Cash flow hedge ineffectiveness adjustment to accumulated other comprehensive income

Due From Related Parties [Abstract]

Net receivable from ComEd

Net receivable from PECO

194

Collateral And Contingent Related Features [Abstract]

Aggregate fair value of derivatives with credit-risk-related contingent features

947

894

Contractual right of offset related to derivative assets

913

778

Net liability position after contractual right of offset

116

Incremental collateral for credit rating downgrade to BBB- and Baa3

Incremental collateral for loss of investment grade credit rating

994

673

Swap Contract Collateral Posting Limit [Abstract]

Swap conrtract collateral posting limit

200

Master Netting Arrangements [Abstract]

Cash collateral received not offset against net derivative positions

EXELON GENERATION CO LLC | Total Exposure Before Credit Collateral Member

1,301

No external ratings - internally rated - investment grade

No external ratings - internally rated - non-investment grade

EXELON GENERATION CO LLC | Credit Collateral Member

1,349

452

No external ratings - internally rated - investment grade

^[5]

No external ratings - internally rated - non-investment grade

EXELON GENERATION CO LLC | Net Exposure Member

463

894

No external ratings - internally rated - investment grade

No external ratings - internally rated - non-investment grade

EXELON GENERATION CO LLC | Number Of Counterparties Greater Than Ten Percent Of Net Exposure Member

886

No external ratings - internally rated - investment grade

No external ratings - internally rated - non-investment grade

EXELON GENERATION CO LLC | Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure Member

No external ratings - internally rated - investment grade

No external ratings - internally rated - non-investment grade

EXELON GENERATION CO LLC | Energy Related Hedges [Member]

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Accumulated OCI derivative gain - Beginning Balance

1,703

^[6]

1,814

^[7]

1,152

^[8]

855

^[9]

$ 1,152

^[8]

$ 1,158

^[6],[8],[10]

Effective portion of changes in fair value

(335)

^[11]

(42)

^[12]

334

^[13]

1,059

^[14]

Accumulated OCI derivative gain - Ending Balance

1,158

^[6],[8],[10]

1,512

^[7],[9]

1,158

^[6],[8],[10]

1,512

^[7],[9]

EXELON GENERATION CO LLC | Cash Flow Hedges [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets with affiliate (current assets)

581

^[2],[15]

581

^[2],[15]

576

^[16]

386

^[2],[15]

386

^[2],[15]

302

^[16]

Mark-to-market derivative assets (noncurrent assets)

396

^[2],[15]

396

^[2],[15]

423

^[16]

Mark-to-market derivative assets with affiliate (noncurrent assets)

629

^[2],[15]

629

^[2],[15]

671

^[16]

Mark-to-market derivative liabilities (current liabilities)

1,992

^[2],[15]

1,992

^[2],[15]

1,972

^[16],[17]

(26)

^[2],[15]

(26)

^[2],[15]

(18)

^[16]

Mark-to-market derivative liabilities (noncurrent liabilities)

(50)

^[2],[15]

(50)

^[2],[15]

(42)

^[16]

Total mark-to-market derivative net assets (liabilities)

(76)

^[2],[15]

(76)

^[2],[15]

(60)

^[16]

1,916

^[2],[15]

1,916

^[2],[15]

1,912

^[16]

EXELON GENERATION CO LLC | Other Derivatives [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets (noncurrent assets)

1,085

913

827

792

Mark-to-market derivative liabilities (current liabilities)

1,912

1,705

(691)

(743)

Mark-to-market derivative liabilities (noncurrent liabilities)

(285)

(183)

Total mark-to-market derivative net assets (liabilities)

(976)

(926)

936

779

EXELON GENERATION CO LLC | Proprietary Trading [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets (noncurrent assets)

194

193

140

102

Mark-to-market derivative liabilities (current liabilities)

334

295

(181)

(172)

Mark-to-market derivative liabilities (noncurrent liabilities)

(114)

(98)

Total mark-to-market derivative net assets (liabilities)

(295)

(270)

EXELON GENERATION CO LLC | Collateral And Netting [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets (noncurrent assets)

(1,442)

^[18]

(1,442)

^[18]

(1,306)

^[19]

(751)

^[18]

(751)

^[18]

(678)

^[19]

Mark-to-market derivative liabilities (current liabilities)

(2,193)

^[18]

(2,193)

^[18]

(1,984)

^[19]

852

^[18]

852

^[18]

735

^[19]

Mark-to-market derivative liabilities (noncurrent liabilities)

443

^[18]

443

^[18]

302

^[19]

Total mark-to-market derivative net assets (liabilities)

1,295

^[18]

1,295

^[18]

1,037

^[19]

(898)

^[18]

(898)

^[18]

(947)

^[19]

EXELON GENERATION CO LLC | Operating Revenue [Member]

Proprietary Trading Activities [Abstract]

(6)

(22)

(12)

(43)

EXELON GENERATION CO LLC | Operating Revenue [Member] | Energy Related Hedges [Member]

(19)

(40)

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Reclassifications from accumulated OCI to net income

(211)

^[20]

(262)

^[21]

(328)

^[22]

(407)

^[23]

EXELON GENERATION CO LLC | Purchased Power [Member]

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(72)

(114)

181

142

(77)

(50)

(146)

(96)

EXELON GENERATION CO LLC | Purchased Power [Member] | Energy Related Hedges [Member]

(149)

(164)

Cash Flow Hedge Accumulated Other Comprehensive Income [Abstract]

Ineffective portion recognized in income

EXELON GENERATION CO LLC | Fuel [Member]

Other Derivatives Not Designated As Hedging Instruments [Abstract]

(59)

(102)

$ (6)

$ (26)

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative liabilities (current liabilities)

(6)

Mark-to-market derivative liability with affiliate (current liability)

(383)

(302)

Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)

(627)

(669)

Total mark-to-market derivative net assets (liabilities)

(1,016)

(1,016)

Swap Contract Volumes [Abstract]

Swap contract volumes

3,000

Cost Of Capital Strategies [Abstract]

Pre-tax net income impact associated with a hypothetical 10% increase in interest rates - exclusive upper bound

Fair Value Balances [Abstract]

Fair value swap contract current liability

383

302

Fair value swap contract noncurrent liability

627

669

Cash Flow Hedges [Abstract]

Net unrealized pre-tax gain (loss) on effective cash flow hedges

Net unrealized gain (loss) on effective cash flow hedges, net of tax

Swap Contract Collateral Posting Limit [Abstract]

Swap conrtract collateral posting limit

200

COMMONWEALTH EDISON CO | Cash Flow Hedges [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative liabilities (current liabilities)

^[24]

(6)

Total mark-to-market derivative net assets (liabilities)

^[24]

(6)

^[24]

(6)

Interest Rate Risk - Cash Flow Hedges [Abstract]

Notional amount of interest rate cash flow hedge derivatives

300

COMMONWEALTH EDISON CO | Il Settlement Swap [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative liability with affiliate (current liability)

(383)

^[2]

(383)

^[2]

(302)

^[16]

Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)

(627)

^[2]

(627)

^[2]

(669)

^[16]

Total mark-to-market derivative net assets (liabilities)

(1,010)

^[2]

(1,010)

^[2]

(971)

^[16]

(1,010)

^[2]

(1,010)

^[2]

(971)

^[16]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative liabilities (current liabilities)

(2)

Mark-to-market derivative liability with affiliate (current liability)

(3)

Mark-to-market derivative liabilities (noncurrent liabilities)

(2)

Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)

(2)

$ (2)

(2)

Percent Of Gas Purchases Being Hedged [Abstract]

Percent of natural gas purchases hedged

22%-29%

Fair Value Balances [Abstract]

Fair value block contract current liabilities

$ 3

Fair value block contract noncurrent liabilities

Cash Flow Hedges [Abstract]

Net unrealized gain (loss) related to fair value block contract, net of tax

$ 1

Natural Gas Supply And Management Agreement Credit Exposure [Abstract]

Credit exposure under natural gas supply and management agreements

Collateral And Contingent Related Features [Abstract]

Incremental collateral for loss of investment grade credit rating

PECO ENERGY CO | Other Derivatives [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative liabilities (current liabilities)

^[15]

(2)

Mark-to-market derivative liability with affiliate (current liability)

^[15]

(3)

Mark-to-market derivative liabilities (noncurrent liabilities)

(2)

^[15]

(2)

^[15]

(2)

^[25]

Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)

(2)

^[15]

(2)

^[15]

(2)

^[25]

Total mark-to-market derivative net assets (liabilities)

(9)

^[15]

(9)

^[15]

(4)

^[25]

(9)

^[15]

(9)

^[15]

(4)

^[25]

Other Segment [Member] | Other Derivatives [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets (noncurrent assets)

Total mark-to-market derivative net assets (liabilities)

Other Segment [Member] | Business Intersegment Eliminations [Member]

Derivative Instruments In Statement Of Financial Position Fair Value [Abstract]

Mark-to-market derivative assets with affiliate (current assets)

(386)

^[2]

(386)

^[2]

(302)

^[16]

Mark-to-market derivative assets with affiliate (noncurrent assets)

(629)

^[2]

(629)

^[2]

(671)

^[16]

Mark-to-market derivative liability with affiliate (current liability)

(1,015)

^[2]

(1,015)

^[2]

(973)

^[16]

386

^[2]

386

^[2]

302

^[16]

Mark-to-market derivative liabilities with affiliate (noncurrent liabilities)

629

^[2]

629

^[2]

671

^[16]

Total mark-to-market derivative net assets (liabilities)

$ 1,015

^[2]

$ 1,015

^[2]

973

^[16]

^[16]

$ 0

[1]	Includes $4 million of losses, net of taxes, related to the effective portion of changes in fair value of treasury rate locks at ComEd.
[2]	Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $383 million and $627 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.
[3]	Current and noncurrent assets are shown net of collateral of $586 million and $309 million, respectively, and current liabilities are shown inclusive of collateral of $3 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received and offset against mark-to-market assets and liabilities was $898 million at June 30, 2010.
[4]	Current and noncurrent assets are shown net of collateral of $502 million and $376 million, respectively, and current liabilities are shown inclusive of collateral of $69 million, respectively. The allocation of collateral had no impact on noncurrent liabilities. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $947 million at December 31, 2009.
[5]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[6]	Includes $610 million and $746 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $4 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and March 31, 2010, respectively.
[7]	Includes $624 million and $712 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and March 31, 2009, respectively.
[8]	Includes $610 million and $585 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd, and $3 million and $1 million of gains, net of taxes, related to the fair value of the block contracts with PECO as of June 30, 2010 and December 31, 2009, respectively.
[9]	Includes $624 million and $275 million of gains, net of taxes, related to the fair value of the five-year financial swap contract with ComEd as of June 30, 2009 and December 31, 2008, respectively.
[10]	Excludes $5 million gains, net of taxes, related to interest rate swaps settled in 2010.
[11]	Includes a $73 million loss, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $1 million loss, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the three months ended June 30, 2010.
[12]	Includes a $52 million gain, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd during the three months ended June 30, 2009.
[13]	Includes a $122 million gain, net of taxes, related to the effective portion of changes in fair value of the five-year financial swap contract with ComEd, and a $2 million gain, net of taxes, of the effective portion of changes in fair value of the block contracts with PECO for the six months ended June 30, 2010.
[14]	Includes a $401 million gain, net of taxes, of the effective portion of changes in fair value of the five-year financial swap contract with ComEd during the six months ended June 30, 2009.
[15]	Includes current and noncurrent assets for Generation and current and noncurrent liabilities for PECO of $3 million and $2 million, respectively, related to the fair value of PECO's block contracts with Generation. There were no netting adjustments or collateral received
[16]	Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $302 million and $669 million, respectively, related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above.
[17]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[18]	Represents the netting of fair value balances with the same counterparty and the application of collateral.
[19]	Represents the netting of fair value balances with the same counterparty and the application of collateral.
[20]	Includes a $63 million loss, net of taxes, of reclassifications from accumulated OCI to net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2010.
[21]	Includes a $36 million loss, net of taxes, of reclassifications from accumulated OCI to net income related to the settlements of the five-year financial swap contract with ComEd for the three months ended June 30, 2009.
[22]	Includes a $97 million loss, net of taxes, of reclassifications from accumulated OCI to net income related to the settlements of the five-year financial swap contract with ComEd for the six months ended June 30, 2010.
[23]	Includes a $52 million loss, net of taxes, of reclassifications from accumulated OCI to net income related to the settlements of the five-year financial swap contract with ComEd during the six months ended June 30, 2009.
[24]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[25]	Includes a noncurrent liability for PECO and a noncurrent asset for Generation of $2 million related to the fair value of PECO's block contracts with Generation. There were no netting adjustments or collateral received as of December 31, 2009.

Retirement Benefits (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Mar. 31, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2009

Pension And Postretirement Benefit Costs [Abstract]

$ 288

$ 263

Valuation Adjustment Impact [Abstract]

$ 20

$ 18

Accumulated other comprehensive loss (increase) decrease due to an updated valuation adjustment

$ (18)

(28)

Expected Defined Benefit Plan Contributions [Abstract]

Expected discretionary defined benefit plan contribution

954

$ 500

Investment Strategy [Abstract]

Target asset allocation for public equity investments

30.00%

Target asset allocation for fixed income investments

50.00%

Target asset allocation for alternative investments

20.00%

After-tax charge to income tax expense as a result of health care reform legislation

$ 65

Excise tax rate on certain high-cost benefit plans

40.00%

Securities Lending Programs [Abstract]

Percentage of collateral for borrowed securities in domestic currency

102.00%

Percentage of collateral for borrowed securities in foreign currency

105.00%

Percentage of collateral for borrowed securities required levels

100.00%

Weighted average maturity of the securities within the collateral funds

Fair value of cash and non-cash collateral received for loan securities

$ 121

$ 356

124

365

Pension Plans Defined Benefit [Member]

Components Of Defined Benefit Plan Net Periodic Benefit Costs [Abstract]

Service cost

Interest cost

165

162

330

325

Expected return on assets

(200)

(194)

(400)

(388)

Amortization of:

Prior service cost (benefit)

Actuarial loss

127

Net periodic benefit cost

$ 160

131

Valuation Adjustment Impact [Abstract]

Obligation increase (decrease) due to an updated valuation adjustment

Expected Long-Term Rate Of Return On Plan Assets [Abstract]

Expected long-term rate of return on plan assets

8.50%

Other Postretirement Benefit Plans Defined Benefit [Member]

Components Of Defined Benefit Plan Net Periodic Benefit Costs [Abstract]

Service cost

$ 62

Interest cost

107

102

Expected return on assets

(27)

^[1]

(23)

(54)

(47)

Amortization of:

Transition obligation

Prior service cost (benefit)

(14)

(28)

Actuarial loss

Net periodic benefit cost

$ 128

132

Valuation Adjustment Impact [Abstract]

Obligation increase (decrease) due to an updated valuation adjustment

$ (18)

Expected Long-Term Rate Of Return On Plan Assets [Abstract]

Expected long-term rate of return on plan assets

7.83%

BSC

Pension And Postretirement Benefit Costs [Abstract]

^[2]

$ 24

Pension And Postretirement Benefit Costs [Abstract]

134

120

Expected Defined Benefit Plan Contributions [Abstract]

$ 446

446

After-tax charge to income tax expense as a result of health care reform legislation

$ 24

Securities Lending Programs [Abstract]

Percentage of collateral for borrowed securities in domestic currency

102.00%

Percentage of collateral for borrowed securities in foreign currency

105.00%

Percentage of collateral for borrowed securities required levels

100.00%

Weighted average maturity of the securities within the collateral funds

Fair value of cash and non-cash collateral received for loan securities

$ 129

357

131

$ 366

Pension And Postretirement Benefit Costs [Abstract]

106

Expected Defined Benefit Plan Contributions [Abstract]

310

After-tax charge to income tax expense as a result of health care reform legislation

Pension And Postretirement Benefit Costs [Abstract]

Expected Defined Benefit Plan Contributions [Abstract]

$ 2

$ 4

$ 103

103

After-tax charge to income tax expense as a result of health care reform legislation

$ 9

[1]	Mark-to-market derivative liabilities relating to treasury rate locks were recorded in Other current liabilities on ComEd's Consolidated Balance Sheets.
[2]	These amounts primarily represent amounts billed to Exelon's subsidiaries through intercompany allocations

Corporate Restructuring and Plant Retirements (Details)
$ in Millions

3 Months Ended

6 Months Ended

12 Months Ended

24 Months Ended

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

Jun. 30, 2010

USD ($)

Jun. 30, 2009

USD ($)

May 31, 2011

USD ($)

Dec. 31, 2009

USD ($)

Dec. 31, 2009

USD ($)

Corporate Restructuring Severance Benefit Obligation Rollforward [Abstract]

$ 19

(10)

Plant Retirements Severance Benefit Obligation Rollforward [Abstract]

$ 9

$ 19

SeveranceEstimateAdjustments

(1)

(2)

Plant Retirement Obligations Balance

Expense recorded for the three and six months ended June 30, 2009

$ 40

^[1],[2]

$ 40

^[1],[2]

$ 7

Corporate Restructuring Positions Eliminated [Abstract]

Positions eliminated due to restructuring

500

Corporate Restructuring Program Severance Charges [Abstract]

Original severance cost estimate

$ 40

Severance cost estimate adjustment

$ (6)

Severance cost estimate adjustment - salaries and benefits

(10)

Severance cost estimate adjustment - contractual termination benefits

Plant Retirement Positions Eliminated [Abstract]

Positions eliminated due to plant retirements

280

Coal-fired generation units to be retired

Oil/gas-fired generation unit to be retired

Total plant retirement costs

$ 37

Severance benefits expense related to plant retirements

^[1],[2]

Inventory write down related to plant retirements

Plant shut-down costs

Accelerated depreciation expense related to plant retirements

$ 200

Corporate Restructuring Severance Benefit Obligation Rollforward [Abstract]

(2)

Plant Retirements Severance Benefit Obligation Rollforward [Abstract]

SeveranceEstimateAdjustments

(1)

(2)

Plant Retirement Obligations Balance

$ 4

Expense recorded for the three and six months ended June 30, 2009

^[1],[2]

Corporate Restructuring Program Severance Charges [Abstract]

Severance cost estimate adjustment - salaries and benefits

(2)

Restructuring costs

Severance expense billed through intercompany allocations

Stock compensation severance benefit expense

Plant Retirement Positions Eliminated [Abstract]

Positions eliminated due to plant retirements

280

Coal-fired generation units to be retired

Oil/gas-fired generation unit to be retired

Total plant retirement costs

Severance benefits expense related to plant retirements

^[1],[2]

Inventory write down related to plant retirements

Plant shut-down costs

Eddystone Unit 2 monthly revenue for Genco during reliability-must-run period

Cromby Unit 2 monthly revenue for Genco during reliability-must-run period

Accelerated depreciation expense related to plant retirements

$ 20

$ 200

Corporate Restructuring Severance Benefit Obligation Rollforward [Abstract]

(5)

$ 7

Expense recorded for the three and six months ended June 30, 2009

^[1],[2]

Corporate Restructuring Positions Eliminated [Abstract]

Positions eliminated due to restructuring

100

Restructuring costs

Severance expense billed through intercompany allocations

Stock compensation severance benefit expense

Severance benefits expense related to plant retirements

^[1],[2]

Corporate Restructuring Severance Benefit Obligation Rollforward [Abstract]

(1)

$ 1

Expense recorded for the three and six months ended June 30, 2009

^[1],[2]

Restructuring costs

Severance expense billed through intercompany allocations

Severance benefits expense related to plant retirements

^[1],[2]

BSC

Corporate Restructuring Severance Benefit Obligation Rollforward [Abstract]

(2)

$ 6

$ 8

Expense recorded for the three and six months ended June 30, 2009

^[1],[2]

Corporate Restructuring Positions Eliminated [Abstract]

Positions eliminated due to restructuring

400

Severance benefits expense related to plant retirements

^[1],[2]

$ 2

[1]	The amounts above include $8 million, $5 million and $3 million at Generation, ComEd and PECO, respectively, for amounts billed through intercompany allocations.
[2]	The severance benefits costs include $1 million of stock compensation expense collectively at Generation and ComEd for which the obligation is recorded in equity.

Income Taxes (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

12 Months Ended

96 Months Ended

126 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2010

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2009

Dec. 31, 1999

Dec. 31, 2006

Jun. 30, 2010

35.00%

State income taxes, net of Federal income tax benefit

3.30%

3.60%

(0.10%)

Qualified nuclear decommissioning trust fund income (losses)

(6.70%)

5.70%

(0.70%)

1.90%

Domestic production activities deduction

(2.40%)

(0.90%)

(2.10%)

(1.20%)

Tax exempt income

(0.20%)

(0.10%)

(0.20%)

(0.10%)

(0.20%)

(0.30%)

^[1]

3.00%

(0.30%)

(0.10%)

(0.20%)

(0.40%)

0.20%

(0.20%)

0.10%

28.30%

39.60%

38.20%

35.10%

1999 Sale of Fossil Generating Assets

$ 1,700

Deferred tax gain on sale of fossil generating assets

$ 2,800

Deferred tax gain under involuntary conversion provisions of the IRC

1,600

Deferred tax gain under like-kind exchange provisions of the IRC

$ 1,200

IRS asserted penalties for understatement of tax

196

Potential tax and interest from a successful IRS challenge of involuntary conversion position and like-kind exchange transaction

800

Refund due from the settlement of the 2001 tax method of accounting change for certain overhead costs under SSCM

300

Potential interest expense from a successful IRS challenge of the involuntary conversion and like-kind exchange positions

210

After-tax charge to income tax expense as a result of health care reform legislation

Tax Remeasurement Interest Expense

Tax Method of Accounting for Repairs [Abstract]

$ 235

235

Repair cost cash flow impact

$ 420

35.00%

State income taxes, net of Federal income tax benefit

2.90%

0.70%

4.10%

0.50%

Qualified nuclear decommissioning trust fund income (losses)

(10.00%)

7.30%

(1.00%)

2.60%

Domestic production activities deduction

(3.40%)

(1.10%)

(2.90%)

(1.60%)

Tax exempt income

(0.20%)

(0.10%)

(0.20%)

(0.20%)

^[1]

1.50%

Uncertain Tax Position Remeasurement

(0.20%)

(0.10%)

(0.20%)

(0.10%)

(14.90%)

(4.50%)

(0.80%)

(0.60%)

(0.30%)

8.40%

40.90%

31.50%

35.70%

$ 597

597

After-tax charge to income tax expense as a result of health care reform legislation

Tax Remeasurement Deferred Tax Benefit

Tax Method of Accounting for Repairs [Abstract]

Tax Settlement Refund

$ (40)

(40)

Repair cost cash flow impact

$ 420

35.00%

State income taxes, net of Federal income tax benefit

11.20%

4.60%

7.60%

(0.70%)

(0.40%)

(0.50%)

^[1]

2.70%

Uncertain Tax Position Remeasurement

(0.40%)

(0.50%)

(0.40%)

(0.50%)

Plant basis differences

(0.40%)

(0.30%)

(0.20%)

^[2]

(0.30%)

47.90%

18.30%

(0.20%)

0.20%

(0.10%)

93.10%

38.60%

63.20%

32.90%

1999 Sale of Fossil Generating Assets

$ 467

467

Deferred tax gain on sale of fossil generating assets

2,800

Deferred tax gain under involuntary conversion provisions of the IRC

$ 1,600

Potential tax and interest from a successful IRS challenge of involuntary conversion position and like-kind exchange transaction

520

Potential interest expense from a successful IRS challenge of the involuntary conversion and like-kind exchange positions

160

Competitive Transition Charges

Competitive transition charges collected

$ 1,200

After-tax charge to income tax expense as a result of health care reform legislation

Tax Remeasurement Interest Expense

Tax Remeasurement Current Tax Expense

420

Tax Settlement Refund

$ 360

360

35.00%

State income taxes, net of Federal income tax benefit

(6.80%)

(4.00%)

(6.00%)

(5.40%)

(0.20%)

(0.30%)

^[1]

2.90%

(0.50%)

(0.40%)

Plant basis differences

0.40%

0.10%

0.20%

0.30%

(0.20%)

(0.10%)

(0.20%)

0.10%

27.90%

30.40%

31.50%

29.30%

Competitive transition charges collected

$ 601

601

Competitive Transition Charges

4,800

Stranded costs allowed to be collected through CTCs by the PAPUC

$ 5,300

After-tax charge to income tax expense as a result of health care reform legislation

Tax Remeasurement Interest Expense

Nuclear Decommissioning Asset Retirement Obligation Rollforward [Abstract]

$ (140)

[1]	See Note 7 for further discussion regarding the impact of Health Care Reform Legislation on income tax expense.
[2]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.

Nuclear Decommissioning (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

May 26, 2010

Dec. 31, 2009

Nuclear decommissioning ARO beginning balance

^[1]

$ 3,260

Accretion expense

Costs incurred to decommission retired plants

(7)

Nuclear decommissioning ARO ending balance

^[1]

$ 3,349

3,349

Unrealized Gains (Losses) on Nuclear Decommissioning Trust Fund Investments [Abstract]

Net unrealized gains (losses) on decommissioning trust funds - Regulatory Agreement Units

^[2]

(318)

$ 426

(207)

$ 258

Net unrealized gains (losses) on decommissioning trust funds - Non-Regulatory Agreement Units

^[3]

(94)

115

(59)

Nuclear Decommissioning Asset Retirement Obligation Rollforward Footnotes [Abstract]

Current Portion of ARO

$ 17

Nuclear Decommissioning Trust Fund Investments [Abstract]

NDT fund investments

$ 6,498

6,669

Securities Lending Program [Abstract]

Percentage of collateral for borrowed securities in domestic currency

102.00%

Percentage of collateral for borrowed securities in foreign currency

105.00%

Percentage of collateral for borrowed securities required levels

100.00%

Weighted average maturity of the securities within the collateral funds

Fair value of cash and non-cash collateral received for loan securities

$ 121

356

124

365

NRC Minimum Funding Requirements [Abstract]

NRC fuding assurance parent guarantees

Additional NRC funding assurance parent guarantees

$ 175

Nuclear Decommissioning Asset Retirement Obligation Rollforward [Abstract]

Nuclear decommissioning ARO beginning balance

^[1]

3,260

Accretion expense

Costs incurred to decommission retired plants

(7)

Nuclear decommissioning ARO ending balance

^[1]

3,349

Unrealized Gains (Losses) on Nuclear Decommissioning Trust Fund Investments [Abstract]

Net unrealized gains (losses) on decommissioning trust funds - Regulatory Agreement Units

^[2]

(318)

426

(207)

258

Net unrealized gains (losses) on decommissioning trust funds - Non-Regulatory Agreement Units

^[3]

(94)

$ 115

(59)

$ 51

Nuclear Decommissioning Asset Retirement Obligation Rollforward Footnotes [Abstract]

Current Portion of ARO

Nuclear Decommissioning Trust Fund Investments [Abstract]

NDT fund investments

$ 6,498

6,669

Securities Lending Program [Abstract]

Percentage of collateral for borrowed securities in domestic currency

102.00%

Percentage of collateral for borrowed securities in foreign currency

105.00%

Percentage of collateral for borrowed securities required levels

100.00%

Weighted average maturity of the securities within the collateral funds

Fair value of cash and non-cash collateral received for loan securities

$ 129

357

131

$ 366

NRC Minimum Funding Requirements [Abstract]

NRC fuding assurance parent guarantees

$ 44

Additional NRC funding assurance parent guarantees

$ 175

[1]	Includes $17 million as the current portion of the ARO at June 30, 2010 and December 31, 2009, which is included in other current liabilities on Exelon's and Generation's Consolidated Balance Sheets.
[2]	Gains and losses related to Generation's NDT funds associated with Regulatory Agreement Units are included in regulatory liabilities on Exelon's Consolidated Balance Sheets and noncurrent payables to affiliates on Generation's Consolidated Balance Sheets.
[3]	Gains and losses related to Generation's NDT funds associated with Non-Regulatory Agreement Units are included within other, net in Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income.

Earnings Per Share and Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2010	Jun. 30, 2009	Jun. 30, 2010	Jun. 30, 2009	Dec. 31, 2009
Reconciliation of basic and diluted earnings per share
Net income	$ 445	$ 657	$ 1,194	$ 1,369
Average common shares outstanding - basic	661	659	661	659
Assumed exercise of stock options, performance share awards and restricted stock	1	2	1	2
Average common shares outstanding - diluted	662	661	662	661
Stock options not included in the calculation of diluted common shares outstanding [Abstract]
Stock options not included in the calculation of diluted common shares outstanding	9	6	6	5
Treasury Stock [Abstract]
Treasury Stock, Shares held	35		35		35
Treasury stock, at cost	$ 2,327		$ 2,327		$ 2,328

Commitments and Contingencies (Details) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended	108 Months Ended
Commitments and Contingencies (Details) $ in Millions	Feb. 07, 2010 USD ($)	Jun. 30, 2010 USD ($)	Apr. 30, 2011	May 01, 2020	Dec. 31, 2009 USD ($)	Feb. 09, 2007	Jan. 31, 2005
Increase Decrease In Letters Of Credit And Guarantees
Change in letters of credit		$ (3.0)
Change in guarantees		(37.0)
Guarantees to remediate NDT underfunding		$ 44.0
Proposed Environmental Regulation Standards [Abstract]
Proposed GHG emissions reduction by 2012		3.00%
Proposed GHG emissions reduction by 2020		17.00%
Proposed GHG emissions reduction by 2050		83.00%
Proposed energy effiency required by 2020		20.00%
Proposed minimum GHG emissions by stationary sources to qualify for regulation		100,000
Beginning proposed energy effiency standard		6.00%
Proposed minimum additional GHG emissions by stationary sources after a modification		75,000
Regional Emissions Reduction Organization [Abstract]
Number of states in the Midwest Greenhouse Gas Accord		6
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Capital Leases, Net Investment in Direct Financing Leases		$ 615.0
Total Environmental Investigation and Remediation Reserve [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		170.0			$ 175.0
Portion of Total Related to MGP Investigation and Remediation [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		146.0			149.0
One Year From Balance Sheet Date Member
Increase Decrease In Letters Of Credit And Guarantees
Change in guarantees		(125.0)
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		(23.0)
More Than One And Within Three Years From Balance Sheet Date Member
Increase Decrease In Letters Of Credit And Guarantees
Change in guarantees		56.0
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		51.0
More Than Three And Within Five Years From Balance Sheet Date Member
Increase Decrease In Letters Of Credit And Guarantees
Change in guarantees		(15.0)
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		32.0
More Than Five Years From Balance Sheet Date And Thereafter Member
Increase Decrease In Letters Of Credit And Guarantees
Change in guarantees		48.0
EXELON GENERATION CO LLC
Increase Decrease In Future Energy Sales Commitments
Increase (decrease) in future energy Sales Commitments to third parties		27.0
Current year energy sales to third parties		564.0
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		41.0
Fulfillment of energy purchase commitments		(72.0)
Long Term Contract For Purchase Of Electric Power Share Of Plant Output Being Sold
Megawatts sold under a power purchase agreement			150	300
Increase Decrease In Fuel And Natural Gas Purchase Commitments
Increase (decrease) in future fuel purchase commitments		(658.0)
Fulfillment of fuel purchase commitments		(604.0)
Increase Decrease In Letters Of Credit And Guarantees
Change in letters of credit		(63.0)
Change in guarantees		(70.0)
Environmental Loss Contingency Settlement [Abstract]
Gain Loss Related To Environmental Litigation Settlement		$ 1.2
Site Contingency Shared Liability [Abstract]
Tons of soil disposed		39,000
Tons of leached barium sulfate contained in disposed soil		8,700
Total cost of remediation to be shared by PRPs		$ 37.0
Asbestos Loss Contingency [Abstract]
Asbestos liability reserve		53.0			49.0
Asbestos liability reserve related to open claims		$ 15.0
Open asbestos liability claims		171
Asbestos liability reserve related to anticipated claims		$ 38.0
Increase (decrease) in the value of the asbestos liability reserve		4.0
Emission Credits or Allowances [Abstract]
Emission Credits or Allowances		71.0
Emission Credits or Allowances Expected to Be Unused		58.0
EXELON GENERATION CO LLC \| Teg Tep [Member]
Guarantees Related To Sithe
Sale of interest in subsidiary						49.50%
Maximum exposure related to guarantees		95.0
Guarantees Related To Teg Tep
Proceeds from sale of equity method investments	$ 95.0
EXELON GENERATION CO LLC \| Sithe [Member]
Guarantees Related To Sithe
Sale of interest in subsidiary							100.00%
Guarantees related to sale of subsidiary		5.0
Acquisition of interest in subsidiary							0.5
Maximum exposure related to guarantees		200.0
EXELON GENERATION CO LLC \| Total Environmental Investigation and Remediation Reserve [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		15.0			17.0
EXELON GENERATION CO LLC \| Portion of Total Related to MGP Investigation and Remediation [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		0.0			0.0
EXELON GENERATION CO LLC \| More Than One And Within Two Years From Balance Sheet Date Member
Increase Decrease In Future Energy Sales Commitments
Increase (decrease) in future energy Sales Commitments to third parties		428.0
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		4.0
EXELON GENERATION CO LLC \| More Than Two And Within Three Years From Balance Sheet Date Member
Increase Decrease In Future Energy Sales Commitments
Increase (decrease) in future energy Sales Commitments to third parties		123.0
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		4.0
EXELON GENERATION CO LLC \| More Than Three And Within Four Years From Balance Sheet Date Member
Increase Decrease In Future Energy Sales Commitments
Increase (decrease) in future energy Sales Commitments to third parties		40.0
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		5.0
EXELON GENERATION CO LLC \| More Than Four And Within Five Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		7.0
EXELON GENERATION CO LLC \| More Than Five Years From Balance Sheet Date And Thereafter Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		58.0
COMMONWEALTH EDISON CO
Increase Decrease In Renewable Energy Credit Purchase Commitments
Current year renewable energy credit purchases		1.0
Increase (decrease) in renewable energy credit purchase commitments		10.0
Increase Decrease In Letters Of Credit And Guarantees
Change in letters of credit		(55.0)
Cash collateral to replace letters of credit		$ 120.0
Mgp Site Contingency [Abstract]
Total number of MGP sites		42
Approved clean-up		11
Sites under study/remediation		24
COMMONWEALTH EDISON CO \| Total Environmental Investigation and Remediation Reserve [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		$ 111.0			113.0
COMMONWEALTH EDISON CO \| Portion of Total Related to MGP Investigation and Remediation [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		104.0			107.0
COMMONWEALTH EDISON CO \| More Than Two But Less Than Three Years Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		15.0
COMMONWEALTH EDISON CO \| One Year From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		195.0
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		(7.0)
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		12.0
COMMONWEALTH EDISON CO \| More Than One And Within Two Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		206.0
Increase Decrease In Renewable Energy Credit Purchase Commitments
Current year renewable energy credit purchases		9.0
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		5.0
COMMONWEALTH EDISON CO \| More Than One And Within Three Years From Balance Sheet Date Member
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		5.0
COMMONWEALTH EDISON CO \| More Than Two And Within Three Years From Balance Sheet Date Member
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		4.0
COMMONWEALTH EDISON CO \| More Than Three And Within Five Years From Balance Sheet Date Member
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		6.0
PECO ENERGY CO
Increase Decrease In Renewable Energy Credit Purchase Commitments
Increase (decrease) in renewable energy credit purchase commitments		21.0
Annual commitment for purchase of renewable energy credits		2.0
Increase Decrease In Fuel And Natural Gas Purchase Commitments
Change In natural gas purchase commitments		52.0
Increase Decrease In Letters Of Credit And Guarantees
Change in letters of credit		$ (8.0)
Mgp Site Contingency [Abstract]
Total number of MGP sites		27
Approved clean-up		16
Sites under study/remediation		9
PECO ENERGY CO \| Total Environmental Investigation and Remediation Reserve [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		$ 44.0			45.0
PECO ENERGY CO \| Portion of Total Related to MGP Investigation and Remediation [Member]
Accrued environmental liabilities
Accrual For Environmental Loss Contingencies		42.0			$ 42.0
PECO ENERGY CO \| One Year From Balance Sheet Date Member
Increase Decrease In Fuel And Natural Gas Purchase Commitments
Change In natural gas purchase commitments		23.0
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		(31.0)
PECO ENERGY CO \| More Than One And Within Two Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		1,346.0
Increase Decrease In Fuel And Natural Gas Purchase Commitments
Change In natural gas purchase commitments		29.0
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		11.0
PECO ENERGY CO \| More Than One And Within Three Years From Balance Sheet Date Member
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		15.0
PECO ENERGY CO \| More Than Two And Within Three Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		248.0
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		8.0
PECO ENERGY CO \| More Than Three And Within Four Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		56.0
Increase Decrease In Regulatory Construction Commitments
Changes in construction commitments		9.0
PECO ENERGY CO \| More Than Three And Within Five Years From Balance Sheet Date Member
Increase Decrease In Unrecorded Unconditional Purchase Obligation [Abstract]
Increase (decrease) in other purchase obligations		4.0
PECO ENERGY CO \| More Than Four And Within Five Years From Balance Sheet Date Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		25.0
PECO ENERGY CO \| More Than Five Years From Balance Sheet Date And Thereafter Member
Increase Decrease In Future Energy Purchase Commitments
Increase (decrease) in future energy purchase commitments from third parties		25.0
Oyster Creek Generating Station [Member] \| EXELON GENERATION CO LLC
Environmental Loss Contingency Estimate [Abstract]
Low end of range of cooling tower cost		700.0
High end of range of cooling tower cost		800.0
Salem Generating Station [Member] \| EXELON GENERATION CO LLC
Environmental Loss Contingency Estimate [Abstract]
Low end of range of cooling tower cost		$ 500.0

Supplemental Financial Information (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Mar. 31, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2009

Mar. 31, 2007

Depreciation, Amortization and Accretion [Abstract]

$ 279

$ 237

$ 558

$ 475

Asset retirement obligation accretion

^[1]

240

202

475

400

Nuclear fuel

^[2]

168

139

323

272

^[3]

106

737

631

1,455

1,253

Net realized income on decommissioning trust funds - Regulatory Agreement Units

^[4]

Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units

^[4]

Net unrealized losses on decommissioning trust funds - Regulatory Agreement Units

(318)

426

(207)

258

Net unrealized losses on decommissioning trust funds - Non-Regulatory Agreement

(94)

115

(59)

Regulatory offset to decommissioning trust fund-related activities

^[5]

215

(349)

(234)

Total decommissioning-related activities

(134)

212

(55)

121

Investment income

Net direct financing lease income

Interest income related to uncertain income tax positions

^[6]

Other-than-temporary impairment to Rabbi trust investments

^[7]

(7)

^[8]

(122)

257

(29)

219

Pension and non-pension postretirement benefits costs

288

263

Stock-based compensation costs

Other decomissioning-related activity

^[5]

(43)

Energy-related options

^[9]

(36)

Amortization of regulatory asset related to debt costs

Accrual for Illinois utility distribution tax refund

^[10]

(25)

Amortization of the regulatory liability related to the PURTA tax settlement

^[11]

(2)

Under-recovered uncollectible accounts

^[12]

(49)

Other-than-temporary impairment to Rabbi trust investments

^[7]

^[8]

(8)

Changes In Other Assets and Liabilities [Abstract]

278

411

Under/over-recovered energy and transmission costs

(172)

(150)

103

(105)

(9)

(197)

9,341

^[13]

9,341

^[13]

$ 9,023

^[14]

Accumulated Other Comprehensive Income (Loss) [Abstract]

228

225

Pension and non-pension postretirement benefit plans

525

551

(2,603)

(2,640)

Total accumulated other comprehensive income (loss)

(2,078)

(2,089)

Under-recovered uncollectible accounts expense from 2008 and 2009

$ 70

Regulatory liability - refund of real estate taxes

$ 38

Nuclear fuel accumulated amortization

1,384

1,383

Reduction in tax other than income

Depreciation, Amortization and Accretion [Abstract]

Asset retirement obligation accretion

115

223

149

Nuclear fuel

^[2]

168

139

323

272

^[3]

105

332

264

645

526

Net realized income on decommissioning trust funds - Regulatory Agreement Units

^[4]

Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units

^[4]

Net unrealized losses on decommissioning trust funds - Regulatory Agreement Units

(318)

426

(207)

258

Net unrealized losses on decommissioning trust funds - Non-Regulatory Agreement

(94)

115

(59)

Regulatory offset to decommissioning trust fund-related activities

^[5]

215

(349)

(234)

Total decommissioning-related activities

(134)

212

(55)

121

Interest income related to uncertain income tax positions

^[6]

(133)

215

(54)

133

Pension and non-pension postretirement benefits costs

134

120

Other decomissioning-related activity

^[5]

(31)

(43)

Energy-related options

^[9]

(36)

Changes In Other Assets and Liabilities [Abstract]

133

113

(57)

(5)

(16)

(34)

(21)

4,395

^[13]

4,395

^[13]

4,214

^[14]

Accumulated Other Comprehensive Income (Loss) [Abstract]

Total accumulated other comprehensive income (loss)

1,163

1,157

1,163

1,157

Nuclear fuel accumulated amortization

1,384

1,383

Depreciation, Amortization and Accretion [Abstract]

117

112

234

221

^[1]

131

124

261

246

Interest income related to uncertain income tax positions

^[6]

Other-than-temporary impairment to Rabbi trust investments

^[7]

(7)

Pension and non-pension postretirement benefits costs

106

Amortization of regulatory asset related to debt costs

^[15],[16]

Accrual for Illinois utility distribution tax refund

^[10]

(25)

Under-recovered uncollectible accounts

^[12]

(49)

Other-than-temporary impairment to Rabbi trust investments

^[7]

Changes In Other Assets and Liabilities [Abstract]

159

Under/over-recovered energy and transmission costs

(82)

(34)

2,240

2,129

Accumulated Other Comprehensive Income (Loss) [Abstract]

Total accumulated other comprehensive income (loss)

(4)

(4)

Under-recovered uncollectible accounts expense from 2008 and 2009

Reduction in tax other than income

Depreciation, Amortization and Accretion [Abstract]

^[1]

226

190

448

375

268

230

533

455

Interest income related to uncertain income tax positions

Investment income

^[6]

(1)

(1)

Pension and non-pension postretirement benefits costs

$ 6

Amortization of regulatory asset related to debt costs

Amortization of the regulatory liability related to the PURTA tax settlement

^[11]

(2)

(3)

Changes In Other Assets and Liabilities [Abstract]

Under/over-recovered energy and transmission costs

^[17]

(127)

(137)

(2)

(74)

$ (128)

2,488

2,442

Accumulated Other Comprehensive Income (Loss) [Abstract]

114

117

Total accumulated other comprehensive income (loss)

$ 0

$ 1

Regulatory liability - refund of real estate taxes

$ 38

[1]	For PECO, primarily reflects CTC amortization.
[2]	Included in fuel expense on the Registrants' Consolidated Statements of Operations.
[3]	Included in operating and maintenance expense on the Registrants' Consolidated Statements of Operations.
[4]	Includes investment income and realized gains and losses on sales of investments of the trust funds.
[5]	Includes the elimination of NDT fund related activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity. See Note 11 of the 2009 Form 10-K for additional information regarding the accounting for nuclear decommissioning.
[6]	Primarily includes interest income at Generation and ComEd related to the February 2009 Illinois Supreme Court decision regarding refund claims for Illinois investment tax credits, which was reversed in the third quarter of 2009. See Note 10 of the 2009 Form 10-K for additional information.
[7]	ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009.
[8]	ComEd recorded an other-than-temporary impairment to Rabbi trust investments during the second quarter of 2009. See Note 4 - Fair Value of Financial Assets and Liabilities for additional information regarding the impairment.
[9]	Reclassification of energy-related option premiums to realized at settlement of contracts recorded in results of operations due to the settlement of the underlying transaction.
[10]	During the second quarter, ComEd recorded a reduction of $25 million to taxes other than income to reflect management's estimate of future refunds for the 2008, 2009 and 2010 tax years associated with Illinois' utility distribution tax based on an analysis of past refunds and interpretations of the Illinois Public Utility Act.
[11]	In March 2007, PECO prevailed in a Pennsylvania Supreme Court case in which PECO had contested the assessment of PURTA taxes applicable to 1997. As a result, PECO received approximately $38 million of real estate taxes previously remitted. This refund was recorded as a regulatory liability. PECO began amortizing this liability and refunding customers in January 2008. The regulatory liability associated with the PURTA settlement was fully amortized in January 2009.
[12]	Includes $70 million of under-recovered uncollectible accounts expense from 2008 and 2009 recorded in the first quarter of 2010 as well as subsequent adjustments to and amortization of the associated regulatory asset. ComEd is recovering these costs through a rider mechanism authorized by the ICC. See Note 3 - Regulatory Matters for additional information regarding the Illinois legislation for recovery of uncollectible accounts.
[13]	Includes accumulated amortization of nuclear fuel in the reactor core of $1,384 million.
[14]	Includes accumulated amortization of nuclear fuel in the reactor core of $1,383 million.
[15]	Effective December 31, 2009, Exelon categorizes its NDT commingled funds within the Level 2 fair value hierarchy.
[16]	Includes the reclassification of $2 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the six months ended June 30, 2010. The reclassification due to settlement of derivative contracts for the three months ended June 30, 2010 was insignificant.
[17]	Relates primarily to prepaid utility taxes.

Segment Information (Details) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2010

Jun. 30, 2009

Jun. 30, 2010

Jun. 30, 2009

Dec. 31, 2009

Analysis and reconciliation of reportable segment information

$ 4,398

^[1]

$ 4,141

^[1]

$ 8,859

^[2]

$ 8,863

^[2]

^[3]

^[4]

445

657

1,194

1,369

49,173

$ 49,180

^[3]

^[4]

Analysis and reconciliation of reportable segment information

2,353

^[1],[5],[6]

2,378

^[1],[5],[6]

4,773

^[2],[7],[8]

4,979

^[2],[6],[7]

725

^[3],[5]

833

^[3],[5]

1,552

^[4],[7]

1,777

^[4],[7]

1,454

1,487

3,276

3,404

382

^[5]

512

^[5]

943

^[7]

1,041

^[7]

^[5]

22,499

22,406

Generation Mid Atlantic Member

725

^[3],[5]

833

^[3],[5]

1,552

^[4],[7]

1,777

^[4],[7]

Analysis and reconciliation of reportable segment information

751

^[6]

834

^[6]

1,531

^[8]

1,687

^[8]

470

486

928

991

583

682

1,197

1,377

Generation Midwest Member

470

486

928

991

Analysis and reconciliation of reportable segment information

1,383

^[6]

1,344

^[6]

2,734

^[8]

2,793

^[8]

255

347

624

786

1,016

1,017

2,010

2,090

Analysis and reconciliation of reportable segment information

255

347

624

786

Generation South Member

150

^[6]

171

^[6]

298

^[8]

346

^[6]

Generation Other Activity Member

(43)

(25)

(91)

(58)

Analysis and reconciliation of reportable segment information

^[9]

^[6]

210

^[8]

153

^[8]

^[9]

(102)

(187)

160

(5)

Analysis and reconciliation of reportable segment information

1,499

^[1]

1,389

^[1]

2,914

^[2]

2,942

^[2]

^[3]

^[4]

116

125

230

20,870

20,697

Segment Reporting Information Additional Information

^[3]

^[4]

UtilityTaxes

108

Analysis and reconciliation of reportable segment information

1,269

^[1]

1,204

^[1]

2,724

^[2]

2,718

^[2]

^[3]

^[4]

176

183

9,071

9,019

Segment Reporting Information Additional Information

^[3]

^[4]

UtilityTaxes

130

121

Other Segment [Member]

Analysis and reconciliation of reportable segment information

177

^[1]

207

^[1]

359

^[2]

391

^[2]

177

^[3]

207

^[3]

358

^[4]

391

^[4]

(21)

(35)

(50)

(76)

5,384

6,088

Business Intersegment Eliminations [Member]

177

^[3]

207

^[3]

358

^[4]

391

^[4]

Analysis and reconciliation of reportable segment information

(900)

^[1]

(1,037)

^[1]

(1,911)

^[2]

(2,167)

^[2]

(900)

^[3]

(1,036)

^[3]

(1,911)

^[4]

(2,167)

^[4]

(7)

(9)

(8,651)

$ (9,030)