Fair Value Disclosures [Abstract] Fair Value Assets Liabilities Measured On Recurring Basis [Table] Summarization of information required and determined to be disclosed concerning assets and liabilities, including [financial] instruments that are classified in stockholders' equity, which are measured at fair value on a recurring basis. Fair Value Assets And Liabilities Measured On Recurring Basis Other Disclosure Items [Axis] Fair Value Assets And Liabilities Measured On Recurring Basis Other Disclosure Items [Axis] Provides the other information items required or determined to be disclosed with respect to assets and liabilities, including [financial] instruments that are classified in stockholders' equity, which are measured at fair value on a recurring basis. Fair Value Assets And Liabilities Measured On Recurring Basis Other Disclosure Items [Domain] Fair Value Assets And Liabilities Measured On Recurring Basis Other Disclosure Items [Domain] Provides the other information items required or determined to be disclosed with respect to assets and liabilities, including [financial] instruments that are classified in stockholders' equity, which are measured at fair value on a recurring basis. Pledged Assets For Zion Station Decommissioning [Member] Pledged Assets For Zion Station Decommissioning [Member] This element represents the assets measured at fair value on a recurring basis related to pledged assets for Zion Station decommissioning. Nuclear Decommissioning Trust Fund Investments [Member] Nuclear Decommissioning Trust Fund Investments [Member] This element represents the assets measured at fair value on a recurring basis related to nuclear decommissioning trust fund investments. Cash Equivalents NDT [Member] Cash Equivalents NDT [Member] Cash Equivalents NDT [Member] Equity Securities [Member] Equity Securities [Member] Fixed Income Securities [Member] Fixed Income Securities [Member] Corporate Debt Securities [Member] Corporate Debt Securities [Member] US Treasury and Government [Member] US Treasury and Government [Member] Debt Security, Government, Non-US [Member] Debt Security, Government, Non-US [Member] State and municipal debt [Domain] State and municipal debt [Domain] State and municipal debt [Domain] Other Fixed Income [Member] Other Fixed Income [Member] Other Fixed Income [Member] Middle Market Lending [Member] Middle market lending [Member] Middle market lending [Member] Private Equity Funds [Member] Private Equity Funds [Member] Real Estate Funds [Member] Real Estate Funds [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2016-01 [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Exelon Generation Co L L C [Member] Exelon Generation Co L L C [Member] Exelon Generation Co LLC [Member] Commonwealth Edison Co [Member] Commonwealth Edison Co [Member] Commonwealth Edison Co [Member] Generation Total Consolidated Group [Member] Generation Total Consolidated Group [Member] This member is equivalent to Exelon Generation Co LLC in most cases for segment reporting except for intersegment activity.The consolidated group for intersegment activity represents activity between the segments within the Generation consolidated group as opposed to the activity between Generation and the Exelon consolidated group. PECO Energy Co [Member] PECO Energy Co [Member] PECO Energy Co [Member] Baltimore Gas and Electric Company [Member] Baltimore Gas and Electric Company [Member] Pepco Holdings LLC [Member] Pepco Holdings LLC [Member] Potomac Electric Power Company [Member] Potomac Electric Power Company [Member] Potomac Electric Power Company [Member] Delmarva Power and Light Company [Member] Delmarva Power and Light Company [Member] Delmarva Power and Light Company [Member] Atlantic City Electric Company [Member] Atlantic City Electric Company [Member] Atlantic City Electric Company [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 1, 2 and 3 [Member] Fair Value, Inputs, Level 1, 2 and 3 [Member] Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measured at Net Asset Value Per Share [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Other [Member] Other [Member] Other [Member] Rabbi Trust Investments [Member] Rabbi Trust Investments [Member] This element represents the assets measured at fair value on a recurring basis related to rabbi trust investments. Cash Equivalents [Member] Cash Equivalents [Member] Mutual Funds [Member] Mutual Funds [Member] Mutual Funds [Member] Fixed Income Investments [Member] Fixed Income Investments [Member] 6311 Life Insurance [Member] 6311 Life Insurance [Member] Economic Hedging Instrument [Member] Economic Hedging Instrument [Member] Economic Hedging Instrument [Member] Proprietary Trading [Member] Proprietary Trading [Member] Energy-related derivative contracts entered into purely to profit from market prices changes as opposed to hedging an exposure. Effects of netting and allocation of collateral [Member] Effects of Netting and Allocation of Collateral [Member] Effects of Netting and Allocation of Collateral [Member] Commodity Derivative Assets [Member] Commodity Derivative Assets [Member] Commodity Derivative Assets [Member] Interest rate and foreign currency derivative assets [Member] Interest Rate and Foreign Currency Derivative Assets [Member] Interest Rate and Foreign Currency Derivative Assets [Member] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Economic hedge Interest and Currency [Member] Economic hedge Interest and Currency [Member] Economic hedge Interest and Currency [Member] Effectsofnettingandallocationofcollateral1 [Member] EffectsofNettingandAllocationofCollateral1 [Member] EffectsofNettingandAllocationofCollateral1 [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] Restricted cash member [Member] Restricted cash [Member] Restricted cash [Member] Other Assets [Member] Other Assets [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Commodity Derivative Liabilites [Member] Commodity Derivative Liabilites [Member] Commodity Derivative Liabilites [Member] Economic Hedging Instrument Liabilites [Member] Economic Hedging Instrument Liabilites [Member] Economic Hedging Instrument Liabilites [Member] Proprietary Trading Liabilities [Member] Proprietary Trading Liabilities [Member] Proprietary Trading Liabilities [Member] Effects of Netting and Allocation of Collateral Liabilites [Member] Effects of Netting and Allocation of Collateral Liabilites [Member] Effects of Netting and Allocation of Collateral Liabilites [Member] Interestrateandforeigncurrencyderivativeliabilities [Member] Interest Rate and Foreign Currency Derivative Liabilities [Member] Interest Rate and Foreign Currency Derivative Liabilities [Member] Derivatives Designated As Hedging Instruments Liabilities [Domain] Derivatives Designated As Hedging Instruments Liabilities [Domain] Derivatives Designated As Hedging Instruments Liabilities [Domain] EconomicHedgingInstrumentLiabilites1 [Member] EconomicHedgingInstrumentLiabilites1 [Member] EconomicHedgingInstrumentLiabilites1 [Member] Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain] Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain] Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain] Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items] Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. 0 Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Investments, Fair Value Disclosure Investments, Fair Value Disclosure Derivative Asset Derivative Asset Assets, Fair Value Disclosure Assets, Fair Value Disclosure Total mark-to-market derivative liabilities Derivative Liability Deferred Compensation Liability, Current and Noncurrent Deferred Compensation Liability, Current and Noncurrent Total Liabilities Financial Liabilities Fair Value Disclosure Fair Value, Net Asset (Liability) Fair Value, Net Asset (Liability) Derivative Liability, Fair Value, Amount Not Offset Against Collateral Derivative Liability, Fair Value, Amount Not Offset Against Collateral Mark-to-market derivative liabilities (current liabilities) Derivative Liability, Current Derivative Liability, Noncurrent Derivative Liability, Noncurrent Derivative, Collateral, Right to Reclaim Cash Derivative, Collateral, Right to Reclaim Cash Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Derivative Asset, Notional Amount Derivative Asset, Notional Amount Net assets (liabilities) excluded from nuclear decommissioning trust fund investments Fair Value Net Assets Liabilities Excluded From Nuclear Decommissioning Trust Fund Investments This element represents total net assets (liabilities) excluded from nuclear decommissioning trust fund investment total. The amount consists of payables related to pending securities purchases net of cash, interest receivables and receivables related to pending securities for the respective periods. Collateral received from counterparties, net of collateral paid to counterparties Derivative, Fair Value, Amount Offset Against Collateral, Net Margin Deposit Assets Margin Deposit Assets Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Facility Closing [Member] Facility Closing [Member] Public Utility [Axis] Public Utility [Axis] Utility Plant [Domain] Utility Plant [Domain] Salem [Member] Salem [Member] Nuclear generation facility located in Hancock's Bridge, NJ. Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] Nuclear Plant [Member] Nuclear Plant [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Jointly Owned Utility Plant, Proportionate Ownership Share Jointly Owned Utility Plant, Proportionate Ownership Share Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Cash Collateral Posted Cash Collateral Posted Cash collateral posted related to credit risk. Letters Of Credit Posted Letters Of Credit Posted Letters of credit posted related to credit risk. Cash Collateral Held Cash Collateral Held Cash collateral held related to credit risk. Letters Of Credit Held Letters Of Credit Held Letters of credit held related to credit risk Incremental Collateral For Loss Of Investment Grade Credit Rating Incremental Collateral For Loss Of Investment Grade Credit Rating Incremental collateral amount required to be provided related to its financial instruments, including derivatives, non-derivatives, normal purchase normal sales contracts and applicable payables and receivables, if the credit rating is downgraded below investment grade. Supplemental Financial Information [Abstract] Supplemental Financial Information [Abstract] Supplemental Cash Flow Information [Table] Schedule disclosing additional information about a registrants statement of cash flows Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Unamortized Energy Contracts [Member] Unamortized Energy Contracts [Member] Unamortized Energy Contracts [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Supplemental Cash Flow Information [Line Items] Supplemental Cash Flow Information [Line Items] Supplemental Cash Flow Information [Line Items] Depreciation, Amortization and Accretion [Abstract] Depreciation, Amortization and Accretion, Net [Abstract] Property, plant and equipment Depreciation Amortization of regulatory assets Amortization of Regulatory Asset Amortization of intangible assets, net Amortization of Intangible Assets Amortization of energy contract assets and liabilities Amortization of Power Contracts Emission Credits Nuclear fuel Amortization of Nuclear Fuel Lease ARO accretion Asset Retirement Obligation, Accretion Expense Total depreciation, amortization and accretion Depreciation, Amortization and Accretion, Net Other Non-Cash Operating Activities [Abstract] Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Pension and non-pension postretirement benefit costs Pension and Other Postretirement Benefits Cost (Reversal of Cost) Provision for uncollectible accounts Accounts Receivable, Credit Loss Expense (Reversal) Other decommissioning-related activity Other Decommissioning Related Activity This item represents realized and unrealized gains (losses) for the period as a result of selling and holding marketable securities in nuclear decommissioning trust funds. Additionally, this item includes the elimination of operating revenues, asset retirement obligation accretion, asset retirement cost amortization, investment income and income taxes related to nuclear decommissioning trust fund activity. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement. Energy-related options Energy Related Options Represents the 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. Amortization of rate stabilization deferral Amortization Rate Stabilization Deferral Amortization of deferred costs under BGE rate stabilization Discrete impacts from EIMA and FEJA Impacts Energy Infrastructure Modernization Act Non cash impact recorded to the income statement pursuant to an order and/or ruling by state regulators and/or courts. Long-term incentive plan Employee Benefit and Share-based Payment Arrangement, Noncash Amortization of operating ROU asset Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease Noncash Investing and Financing Items [Abstract] Noncash Investing and Financing Items [Abstract] Acquisition of land Noncash or Part Noncash Acquisition, Fixed Assets Acquired Income Statement [Abstract] Supplemental Statement of Operations Information [Table] Supplemental Statement of Operations Information [Table] Schedule disclosing additional information about a registrants statement of operations. Supplemental Statement of Operations Information [Line Items] Supplemental Statement of Operations Information [Line Items] Supplemental Statement of Operations Information Line Item Utility taxes Utilities Operating Expense, Taxes Property Real Estate Tax Expense Payroll Other Labor-related Expenses Debt Disclosure [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Commercial Paper [Member] Commercial Paper [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Corporate, Non-Segment [Member] Corporate, Non-Segment [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Outstanding Commercial Paper Commercial Paper Average Interest Rate on Commercial Paper Borrowings Short-term Debt, Weighted Average Interest Rate, at Point in Time Fair Value of Financial Assets and Liabilities (All Registrants) Fair Value Disclosures [Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Pepco Holdings LLC [Member] Statement [Line Items] Statement [Line Items] Customer allowance for uncollectible accounts Accounts Receivable, Allowance for Credit Loss, Current Other allowance for uncollectible accounts Allowance for Doubtful Other Receivables, Current Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Common Stock, Shares Authorized Common Stock, Shares Authorized Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Treasury Stock, Shares held Treasury Stock, Shares Variable Interest Entity [Abstract] Variable Interest Entity [Abstract] Variable Interest Entity Disclosure (All Registrants) Variable Interest Entity Disclosure [Text Block] Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Table] Schedule that discloses total realized and unrealized gains/losses included in income for assets and liabilities with unobservable inputs measured on a recurring basis. Pepco Holdings Inc [Member] PEPCO Holdings Inc [Member] PEPCO Holdings Inc [Member] Operating Revenue [Member] Operating Revenue [Member] This element represents the gains (losses) included in earnings that are recognized in operating revenues. Purchased Power And Fuel [Member] Purchased Power And Fuel [Member] Total costs incurred and are directly related to energy commodities and services provided during the reporting period. Operating and Maintenance [Member] Operating and Maintenance [Member] This element represents the gains (losses) included in earnings that are recognized in operating and maintenance expense. Other, net [Member] Other, net [Member] This element represents the gains (losses) included in earnings that recognized in Other, net. Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items] Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Accounting Policies [Abstract] Basis of Accounting, Policy [Policy Text Block] Basis of Accounting, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Revenues [Policy Text Block] Revenue [Policy Text Block] Lessee, Leases [Policy Text Block] Lessee, Leases [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Regulated Operations [Abstract] Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Clean Energy Legislation [Member] Clean Energy Legislation [Member] Clean Energy Legislation [Member] Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Initial Revenue Requirement Increase (Decrease) Public Utilities, Requested Rate Increase (Decrease), Amount Annual Reconciliation Increase (Decrease) Revenue Exepected adjustment to revenue to be recorded in the prior year. Total Revenue Requirement Increase (Decrease) Public Utilities, Requested Rate Increase (Decrease), Amended, Amount Allowed Return on Rate Base, Percentage Public Utilities, Approved Equity Capital Structure, Percentage Allowed Return on Equity, Percentage Public Utilities, Approved Return on Equity, Percentage Proposed Capital Expenditure Proposed Capital Expenditure Proposed Capital Expenditure Cap on Equity Component of Rate of Return on Common Equity in Federal Energy Regulatory Committee Complaint Cap on Equity Component of Rate of Return on Common Equity in Federal Energy Regulatory Committee Complaint The maximum percentage allowed for the equity component of the rate of return on common equity in the Federal Energy Regulatory Committee Complaint. Other Operating Income Other Operating Income Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information [Table] Operating cash flows from operating leases Operating Lease, Payments Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Commitments and Contingencies Disclosure [Abstract] Other Commitments [Table] Other Commitments [Table] Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Rate credits Rate Bill Credits [Member] Rate Bill Credits [Member] Energy efficiency Energy Efficiency Program [Member] Energy Efficiency Program [Member] Charitable contributions Charitable Contributions [Member] Charitable Contributions [Member] Delivery system modernization Delivery System Modernization [Member] Delivery System Modernization [Member] Green sustainability fund Green Sustainability Fund [Member] Green Sustainability Fund [Member] Workforce development Workforce Development [Member] Workforce Development [Member] Other Other1 [Member] Other1 [Member] Remaining commitment Remaining Commitment [Member] Remaining Commitment [Member] Other Commitments [Line Items] Other Commitments [Line Items] Other Commitment Other Commitment Income Tax Disclosure [Abstract] Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Table] Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Table] Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items] Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items] Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items] Effective Income Tax Rate Reconciliation, Percent [Abstract] Effective Income Tax Rate Reconciliation, Percent [Abstract] U.S. Federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Increase (decrease) due to: Adjustments To Reconcile Federal Statutory Income Tax Rate To Effective Income Tax Rate Continuing Operations [Abstract] Adjustments to reconcile the domestic federal statutory tax rate to a company's effective income tax rate abstract. State income taxes, net of Federal income tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Qualified nuclear decommissioning trust fund income Effective Income Tax Rate Reconciliation, Qualified Decommissioning Investment Income, Percent Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to qualified decommissioning investment income taxes paid. Amortization of investment tax credit, including deferred taxes on basis difference Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Percent Plant basis differences Effective Income Tax Rate Reconciliation, Deduction, Other, Percent Production tax credits and other credits Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent Noncontrolling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent Excess deferred tax amortization Effective Income Tax Rate Reconciliation, Change in Enacted Tax Law, Percent Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to change in enacted tax law, excluding changes in the income tax rates. Tax Cuts and Jobs Act of 2017 Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Effective Income Tax Rate Reconciliation, Tax Settlement, Percent Effective Income Tax Rate Reconciliation, Tax Settlement, Percent Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases Future Minimum Payments Due [Table] Operating Leases Future Minimum Payments Due [Table] For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within one year of the balance sheet date relating to leases defined as operating. Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Real Estate Leases and Railroad Licenses [Member] Real Estate Leases and Railroad Licenses [Member] Real Estate Leases and Railroad Licenses [Member] Electrical Conduit System [Member] Electrical Conduit System [Member] Electrical Conduit System [Member] Operating Leases Future Minimum Payments Due [Line Items] Operating Leases Future Minimum Payments Due [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Remaining Years Operating Leases, Future Minimum Payments, Due Thereafter Total Minimum Future Lease Payments Operating Leases, Future Minimum Payments Due Derivative [Table] Derivative [Table] Not Designated as Hedging Instrument, Economic Hedge [Member] Not Designated as Hedging Instrument, Economic Hedge [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Commonwealth Edison Co Affiliate [Member] Commonwealth Edison Co Affiliate [Member] Commonwealth Edison Co Affiliate. PECO Energy Co Affiliate [Member] PECO Energy Co Affiliate [Member] Peco Energy Co Related Party Affiliate Baltimore Gas And Electric Company Affiliate [Member] Baltimore Gas And Electric Company Affiliate [Member] Baltimore Gas and Electric Related Party Affiliate Other Current Assets [Member] Other Current Assets [Member] Derivative, by Nature [Axis] Derivative, Name [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Foreign Exchange Contract [Member] Foreign Exchange Contract [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Derivative [Line Items] Derivative [Line Items] Long-term Purchase Commitment, Minimum Energy Volume Required Long-term Purchase Commitment, Minimum Energy Volume Required Expected Generation Hedged In Next Twelve Months Expected Generation Hedged In Next Twelve Months The percent for the expected/target percentage of future generation being hedged at an electric generation company in the next twelve months. The percentage of expected generation hedged is calculated as 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 affiliates to serve their retail load. Expected Generation Hedged In Year Two Expected Generation Hedged In Year Two The percent for the expected/target percentage of future generation being hedged at an electric generation company in year two. The percentage of expected generation hedged is calculated as 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 affiliates to serve their retail load. Expected generation Hedged In Year Three Expected Generation Hedged In Year Three The percent for the expected/target percentage of future generation being hedged at an electric generation company in year three. The percentage of expected generation hedged is calculated as 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 affiliates to serve their retail load. Derivative, Notional Amount Derivative, Notional Amount Net receivable from electric utility Due From Affiliate Current Electric Utility Amount of receivables due from a electric entity that is affiliated with the reporting entity by means of direct or indirect ownership, due within 1 year (or 1 business cycle). Net receivable from affiliated electric and gas utility Due From Affiliate Current Electric Gas Utility Amount of receivables due from a electric and gas entity that is affiliated with the reporting entity by means of direct or indirect ownership, due within 1 year (or 1 business cycle). Derivative Instruments (All Registrants) Derivative Instruments and Hedging Activities Disclosure [Text Block] Environmental Remediation Obligations [Abstract] Nuclear Decommissioning Additional Narrative Information [Table] Nuclear Decommissioning Additional Narrative Information [Table] Assets, Total [Member] Assets, Total [Member] Nuclear Decommissioning [Member] Nuclear Decommissioning [Member] Represents estimated future nuclear decommissioning costs that exceed (regulatory asset) or are less than (regulatory liability) the associated decommissioning trust fund assets. Oyster Creek [Member] Oyster Creek [Member] Oyster Creek [Member] Three Mile Island [Member] Three Mile Island [Member] Three Mile Island [Member] Nuclear Decommissioning Additional Narrative Information [Line Items] Nuclear Decommissioning Additional Narrative Information [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Asset Retirement Obligation, Period Increase (Decrease) Asset Retirement Obligation Revision Of Estimate In Operating And Maintenance Expense Asset Retirement Obligation Revision Of Estimate In Operating And Maintenance Expense Net amount of the increase (decrease) in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation which is recorded in operating and maintenance expense. Asset Retirement Obligation, Revision of Estimate Asset Retirement Obligation, Revision of Estimate Decommissioning Fund Investments Assets held for sale Disposal Group, Including Discontinued Operation, Assets, Current Membership Interest [Member] Membership Interest [Member] An ownership interest in a limited liability company. Common Stock [Member] Common Stock [Member] Other Paid-in-Capital [Member] Other Additional Capital [Member] Retained Earnings, Unappropriated/Undistributed [Member] Retained Earnings, Unappropriated [Member] Retained Earnings, Appropriated Retained Earnings, Appropriated [Member] Treasury Stock [Member] Treasury Stock [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Other Comprehensive Income (Loss) [Member] Other Comprehensive Income (Loss) [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Shares, Issued Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance Stockholders' Equity Attributable to Parent Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Stock issued during period, shares, long-term incentive plan activity Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture Stock issued during period, value, long-term incentive plan activity Shares Issued, Value, Share-based Payment Arrangement, before Forfeiture Stock issued during period, shares, employee stock purchase plan Stock Issued During Period, Shares, Employee Stock Purchase Plans Stock issued during period, value, employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Changes in equity of noncontrolling interests Noncontrolling Interest, Period Increase (Decrease) Sale of noncontrolling interests Noncontrolling Interest, Increase from Sale of Parent Equity Interest Appropriation of retained earnings for future dividends Retained Earnings, Appropriated Common stock dividends Dividends, Common Stock, Cash Distributions to member Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared Contributions from parent Adjustments to Additional Paid in Capital, Other Other comprehensive income (loss), net of income taxes Other Comprehensive Income (Loss), Net of Tax Impact of adoption of Recognition and Measurement of Financial Assets and Liabilities standard Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Ending balance (in shares) Ending balance Ending Balance Ending Balance Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Handley [Member] Handley [Member] Handley [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Payments to Acquire Businesses, Gross Payments to Acquire Businesses, Gross Changes in Accumulated Other Comprehensive Income [Abstract] Changes in Accumulated Other Comprehensive Income [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Reclassification out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Schedule Of Other Comprehensive Income Loss Tax Schedule Of Other Comprehensive Income Loss Tax [Table Text Block] Schedule Of Other Comprehensive Income Loss Tax Commitments and Contingencies (All Registrants) Commitments and Contingencies Disclosure [Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Current assets Variable Interest Entity, Consolidated, Assets, Current Noncurrent assets Variable Interest Entity, Consolidated, Assets, Noncurrent Total assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Current liabilities Variable Interest Entity, Consolidated, Liabilities, Current Noncurrent liabilities Variable Interest Entity, Consolidated, Liabilities, Noncurrent Total liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Commitments And Contingencies Additional Narrative Information [Table] Commitments And Contingencies Additional Narrative Information [Table] Commitments And Contingencies Additional Narrative Information [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Project [Axis] Project [Axis] Project [Domain] Project [Domain] Other Solar Projects [Member] Other Solar Projects [Member] Wind Assets [Member] Wind Assets [Member] Wind Assets [Member] Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Environmental Remediation Site [Domain] Environmental Remediation Site [Domain] West Lake [Member] West Lake [Member] West Lake [Member] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Nuclear Insurance Premiums [Member] Nuclear Insurance Premiums [Member] Retrospective nuclear insurance premiums related to ANI under the Price-Anderson Act and participation in NEIL Claim Type [Axis] Claim Type [Axis] Claim Type Claim Type [Domain] Claim Type [Domain] [Domain] for Claim Type Open Claims [Member] Open Claims [Member] Open Claims Estimated Future Claims [Member] Estimated Future Claims [Member] Estimated Future Claims Commitments And Contingencies Additional Narrative Information [Line Items] Commitments And Contingencies Additional Narrative Information [Line Items] Commitments And Contingencies Additional Narrative Information [Line Items] Business Acquisition, Expected New Generation Mwh Business Acquisition, Expected New Generation Mwh The expected capacity of new generation development related to the acquisition settlement. Other Non-Financial Commitment OtherNonFinancialCommitment1 OtherNonFinancialCommitment1 Purchase Commitment Purchase Commitment Purchase Commitment Accrued Insurance, Current Accrued Insurance, Current Loss Contingency, Undiscounted Amount of Insurance-related Assessment Liability Loss Contingency, Undiscounted Amount of Insurance-related Assessment Liability Maximum liability per nuclear incident Nuclear Insurance Financial Protection Pool Nuclear Operator Maximum Total Assessment Maximum total assessment to be paid by a nuclear operator for a nuclear incident, under the financial protection pool mandated by the Price-Anderson Act. The total amount is calculated by multiplying the total nuclear reactors operated, by the maximum assessment per nuclear reactor. Nuclear financial protection pool value Nuclear Insurance Financial Protection Pool Value Total funds available for nuclear insurance liability claims in a financial protection pool mandated by the Price-Anderson Act. Prepaid Reinsurance Premiums Prepaid Reinsurance Premiums Estimated Insurance Recoveries Estimated Insurance Recoveries Mgp Site Contingency Approved Cleanup Count Mgp Site Contingency Approved Cleanup Count Number of individual manufactured gas plant sites at which the respective state environmental agency has approved a cleanup plan. Mgp Site Contingency Count Mgp Site Contingency Count Total number of individual manufactured gas plant sites with associated possible environmental loss contingencies related to remediation. Mgp Site Contingency Monitoring Count Mgp Site Contingency Monitoring Count Number of individual manufactured gas plant sites where monitoring or remediation activities are occurring. Accrual for Environmental Loss Contingencies, Gross Accrual for Environmental Loss Contingencies, Gross Accrual for Environmental Loss Contingencies, Component Amount Accrual for Environmental Loss Contingencies, Component Amount Liability for Asbestos and Environmental Claims, Gross Liability for Asbestos and Environmental Claims, Gross Open Asbestos Related Personal Injury Claims Loss Contingency, Pending Claims, Number Supplemental Balance Sheet Information [Table] Schedule disclosing additional information about a registrants assets and liabilities in their statement of financial position. Supplemental Balance Sheet Information [Line Items] Supplemental Balance Sheet Information [Line Items] Supplemental Balance Sheet Information. Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents, Current Restricted cash included in other long-term assets Restricted Cash and Cash Equivalents, Noncurrent Total cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Receivables [Abstract] Receivables [Abstract] Unbilled customer revenues Unbilled Receivables, Current Accrued Expenses [Abstract] Accrued Liabilities [Abstract] Compensation-related accruals Accrued Compensation Current Carrying value as of the balance sheet date of obligations incurred and payable for payroll, employee benefits, incentive compensation and vacation. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Taxes accrued Taxes Payable, Current Interest accrued Interest Payable, Current Credit Risk Exposure [Axis] Credit Risk Exposure [Axis] Credit risk exposure segregated by type of scenario. Credit Risk Exposure [Domain] Credit Risk Exposure [Domain] Major categories of credit risk based on the nature and risk. Total Exposure Before Credit Collateral [Member] Total Exposure Before Credit Collateral [Member] Total counterparty exposure before applying/netting collateral. Credit Collateral [Member] Credit Collateral [Member] Credit collateral associated with counterparty exposure. Net Exposure [Member] Net Exposure [Member] Net counterparty exposure after application/netting of collateral. Number Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] Number Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] Number of counterparties greater than 10% of net exposure. Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure [Member] Net exposure of counterparties greater than 10% of net exposure. Investment grade Investment Grade External Credit Rating Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) with external credit-rating that could be used to describe the current status and performance risk of derivatives and guarantee obligations that connote investment grade. Non-investment grade Non Investment Grade External Credit Rating Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) with external credit-rating that could be used to describe the current status and performance risk of derivatives and guarantee obligations that connote non-investment grade. No external ratings - internally rated - investment grade Investment Grade Internal Credit Rating Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) with an entity's internal risk assessment as having low risk. No external ratings - internally rated - non-investment grade Noninvestment Grade Internal Credit Rating Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) with an entity's internal risk assessment as having high risk. Financial institutions Financial Institutions Credit Risk Exposure Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) from group of counterparties comprised of financial institutions. Investor-owned utilities, marketers and power producers Investor Owned Utilities Marketers And Power Producers Credit Risk Exposure Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) from group of counterparties comprised of investor-owned utilities, marketers and power producers. Energy Cooperatives And Municipalities Energy Cooperatives And Municipalities Net credit exposure from energy cooperatives and municipalities Other Other Credit Risk Exposure Credit exposure for all derivative instruments, normal purchase-normal sale, and related payables and receivables (net of collateral and instruments that are subject to master netting agreements) from group of counterparties not separately identified elsewhere. Total Total Credit Risk Exposure Total credit risk exposure. Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Adjustments to reconcile net income to net cash flows provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization Impairment of long-lived assets Impairment of Long-Lived Assets Held-for-use Gain on sales of assets and businesses Gain (Loss) on Sale of Assets and Asset Impairment Charges Deferred income taxes and amortization of investment tax credits Deferred Income Taxes and Tax Credits Net fair value changes related to derivatives Unrealized Gain (Loss) on Derivatives Net realized and unrealized (gains) losses on NDT funds Gain (Loss) on Investments Other non-cash operating activities Other Noncash Income (Expense) Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Receivables Receivables from and payables to affiliates, net Change in Receivables From Payables To Affiliates, Net The net change in related receivables and payables from entities that are affiliated with the reporting entity by means of direct or indirect ownership. A positive value indicates a decrease in the net receivable or an increase in the net payable, while a negative value indicates an increase in the net receivable or a decrease in the net payable. Inventories Increase (Decrease) in Inventories Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Option premiums received (paid), net Changes In Option Premiums Collected Received The net change during the reporting period in option premiums collected and paid. Options reflect the right or obligation to buy or sell an energy-related commodity and are classified in current and long-term mark-to-market derivative assets and liabilities. Collateral (posted) received, net Increase (Decrease) Cash Collateral from Counterparties Income taxes Increase (Decrease) in Income Taxes Payable Pension and non-pension postretirement benefit contributions Payment for Pension and Other Postretirement Benefits Other assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash flows provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Increase (Decrease) in Restricted Cash Increase (Decrease) in Restricted Cash Proceeds from NDT fund sales Proceeds from Sale and Maturity of Other Investments Investment in NDT funds Payments to Acquire Other Investments Acquisition of assets and businesses, net Proceeds from sales of assets and businesses Proceeds from Sale of Property Held-for-sale Changes in Exelon/PHI intercompany money pool Increase (Decrease) Due from Affiliates Other investing activities Payments for (Proceeds from) Other Investing Activities Net cash flows used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Changes in short-term borrowings Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less Proceeds from short-term borrowings with maturities greater than 90 days Proceeds from Short-term Debt, Maturing in More than Three Months Repayments on short-term borrowings with maturities greater than 90 days Repayments of Short-term Debt, Maturing in More than Three Months Issuance of long-term debt Proceeds from Issuance of Long-term Debt Retirement of long-term debt Repayments of Long-term Debt Changes in Exelon/PHI intercompany money pool Increase (Decrease) in Due to Affiliates, Current Contributions from parent Proceeds from Contributions from Parent Dividends paid on common stock Payments of Ordinary Dividends, Common Stock Proceeds from employee stock plans Proceeds from Stock Plans Distributions to member Payments of Distributions to Affiliates Contributions from member Proceeds from Contributions from Affiliates Other financing activities Proceeds from (Payments for) Other Financing Activities Net cash flows provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Increase (Decrease) in cash, cash equivalents and restricted cash Cash and Cash Equivalents, Period Increase (Decrease) Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Repayments of Related Party Debt Repayments of Related Party Debt Proceeds from (Repurchase of) Redeemable Preferred Stock Proceeds from (Repurchase of) Redeemable Preferred Stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Supplemental Cash Flow Information Increase (Decrease) in capital expenditures not paid Capital Expenditures Incurred but Not yet Paid Change in PPE related to ARO update Costs Incurred, Asset Retirement Obligation Incurred Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Electrical Contracting Business [Member] Electrical Contracting Business [Member] Electrical Contracting Business [Member] Business Dispositions [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities, Current Proceeds from Divestiture of Businesses Proceeds from Divestiture of Businesses Asset Retirement Obligation Revision Of Estimate In Operating And Maintenance Expense Commercial Paper Borrowings Schedule of Short-term Debt [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] TMI,OysterCreek [Member] TMOysterCreek [Member] TMOysterCreek [Member] Accelerated depreciation Restructuring and Related Cost, Accelerated Depreciation Accelerated nuclear fuel amortization Nuclear Fuel Amortization The amount of capitalized nuclear fuel costs that are charged to fuel expense during the period using the unit-of-production method. Operating and maintenance Other Cost and Expense, Operating Restructuring and Related Cost, Incurred Cost Restructuring and Related Cost, Incurred Cost Changes in Accumulated Other Comprehensive Income Note [Text Block] Comprehensive Income (Loss) Note [Text Block] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Gains (Losses) on Cash Flow Hedges Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Unrealized Gains (Losses) on Marketable Securities Pension and Non-Pension Postretirement Benefit Plan Items Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Foreign Currency Items Accumulated Foreign Currency Adjustment Attributable to Parent [Member] AOCI of Investments in Unconsolidated Affiliates Accumulated Equity Investment [Member] Total Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Movement in Accumulated Other Comprehensive Income [Roll Forward] Movement in Accumulated Other Comprehensive Income [Roll Forward] Movement in Accumulated Other Comprehensive Income [Roll Forward] OCI before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from AOCI Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Other comprehensive income Impact of adoption of Recognition and Measurement of Financial Assets and Liabilities standard(c) Marketable Securities, Unrealized Gain (Loss) Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017. Accrual For Environmental Loss Contingencies [Table] Accrual For Environmental Loss Contingencies [Table] Accrual For MGP Investigation And Remediation [Member] Accrual For MGP Investigation And Remediation [Member] Represents the portion of the total environmental investigation and remediation reserve related to manufactured gas plant investigation and remediation. Accrual For Environmental Loss Contingencies [Line Items] Accrual For Environmental Loss Contingencies [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Total environmental investigation and remediation reserve ASSETS Assets [Abstract] Current Assets Assets, Current [Abstract] Cash and cash equivalents Restricted cash and cash equivalents Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current [Abstract] Customer Accounts Receivable, after Allowance for Credit Loss, Current Other Other Receivables Mark-to-market derivative assets, current Derivative Asset, Current Receivable from affiliates, current Accounts Receivable, Related Parties, Current Receivable from Exelon/PHI intercompany money pool Due from Affiliate, Current Unamortized energy contract assets, current Energy Marketing Contracts Assets, Current Inventories, net Inventory, Net [Abstract] Fossil fuel and emission allowances Energy Related Inventory, Natural Gas in Storage Materials and supplies Inventory, Raw Materials and Supplies, Net of Reserves Inventories, net Inventory, Net Prepaid utility taxes Prepaid Taxes Renewable energy credits Renewable Energy Credits, Current Carrying value as of the balance sheet date of renewable energy credits purchased Regulatory assets, current Regulatory Assets, Current Other Other Assets, Current Total current assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net Deferred debits and other assets Other Assets, Noncurrent [Abstract] Regulatory assets, noncurrent Regulatory Assets, Noncurrent Nuclear decommissioning trust funds Investments Long-term Investments Goodwill Goodwill Receivable from affiliates, noncurrent Accounts Receivable, Related Parties, Noncurrent Mark-to-market derivative assets, noncurrent Derivative Asset, Noncurrent Prepaid pension asset Assets for Plan Benefits, Defined Benefit Plan Unamortized energy contract assets, noncurrent Energy Marketing Contracts Assets, Noncurrent Deferred income taxes Deferred Tax Assets, Net, Noncurrent Other Other Assets, Noncurrent Total deferred debits and other assets Deferred Costs and Other Assets Total assets Assets Liabilities and Equity [Abstract] Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Short-term borrowings Short-term Debt Long-term debt due within one year Long-term Debt and Lease Obligation, Current Accounts payable Accounts Payable, Current Accrued expenses Accrued Liabilities, Current Payable to affiliates, current Accounts Payable, Related Parties, Current Borrowings from Exelon/PHI intercompany money pool Due to Affiliate, Current Customer deposits Customer Deposits, Current Regulatory liabilities, current Regulatory Liability, Current Mark-to-market derivative liabilities, current Unamortized energy contract liabilities, current Energy Marketing Contract Liabilities, Current Renewable energy credit obligation Energy Marketing Accounts Payable Merger related obligation Broker-Dealer, Payable to Customer Current portion of DC PLUG obligation Accrued Liabilities and Other Liabilities Other Other Liabilities, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Long-term debt to financing trusts Due to Affiliate, Noncurrent Long-term debt to affiliates Notes Payable, Related Parties, Noncurrent Deferred credits and other liabilities Other Liabilities, Noncurrent [Abstract] Deferred income taxes and unamortized investment tax credits Deferred Income Taxes and Other Tax Liabilities, Noncurrent Asset retirement obligations, noncurrent Asset Retirement Obligations, Noncurrent Pension obligations Liability, Defined Benefit Pension Plan, Noncurrent Non-pension postretirement benefit obligations Liability, Other Postretirement Defined Benefit Plan, Noncurrent Spent nuclear fuel obligation Spent Nuclear Fuel Obligation, Noncurrent Payables to affiliates, noncurrent Accounts Payable, Related Parties, Noncurrent Regulatory liabilities, noncurrent Regulatory Liability, Noncurrent Mark-to-market derivative liabilities, noncurrent Unamortized energy contract liabilities, noncurrent Energy Marketing Contract Liabilities, Noncurrent Other Other Liabilities, Noncurrent Total deferred credits and other liabilities Deferred Credits and Other Liabilities Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Shareholders' equity Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Treasury stock, at cost Treasury Stock, Value Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss, net Accumulated Other Comprehensive Income (Loss), Net of Tax Other paid-in capital Additional Paid in Capital Retained deficit unappropriated Retained Earnings, Unappropriated Retained earnings appropriated Total shareholders’ equity Equity Members Equity Including Portion Attributable To Noncontrolling Interest [Abstract] Members' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Member’s equity Members' Equity [Abstract] Membership interest Members' Capital Total members' equity Members' Equity Noncontrolling Interests Members' Equity Attributable to Noncontrolling Interest Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total equity Total liabilities and shareholders’ equity Liabilities and Equity Variable Interest Entity, Consolidated, Assets, Pledged Variable Interest Entity, Consolidated, Assets, Pledged Variable Interest Entity, Consolidated, Liabilities, No Recourse Lessee Disclosure [Abstract] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Significant Lease, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Contracted Generation [Member] Long-term Contract for Purchase of Electric Power [Member] Long-term Contract for Purchase of Electric Power Real Estate [Member] Real Estate [Member] Vehicles & Equipment [Member] Vehicles [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Lessee, Operating Lease, Description Lessee, Operating Lease, Description Remaining lease terms Lessee, Operating Lease, Term of Contract Options to extend the term Lessee, Operating Lease, Option to Extend Options to terminate within Lessee, Operating Lease, Option to Terminate Income Tax Additional Narrative Information [Table] Income Tax Additional Narrative Information [Table] Income Tax Additional Disclosure [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] ILLINOIS ILLINOIS Income Tax Additional Narrative Information [Line Items] Income Tax Additional Narrative Information [Line Items] Income Tax Additional Disclosure [Line Items] Unrecognized Tax Benefits, Period Increase (Decrease) Unrecognized Tax Benefits, Period Increase (Decrease) Decrease in Unrecognized Tax Benefits is Reasonably Possible Decrease in Unrecognized Tax Benefits is Reasonably Possible Unrecognized tax benefits that if recognized would affect the effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Effective income tax rate Lessee, Operating Lease, Liability, Payment, Due [Abstract] Schedule of Lessee, Operating Lease, Liability, Maturity [Table] Schedule of Lessee, Operating Lease, Liability, Maturity [Table] Schedule of Lessee, Operating Lease, Liability, Maturity Schedule of Lessee, Operating Lease, Liability, Maturity [Line Items] Schedule of Lessee, Operating Lease, Liability, Maturity [Line Items] [Line Items] for Schedule of Lessee, Operating Lease, Liability, Maturity 2019 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four Remaining Years Lessee, Operating Lease, Liability, Payments, Due after Year Five Total Lessee, Operating Lease, Liability, Payments, Due Interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Total Operating Lease Liabilities Operating Lease, Liability Investments [Member] Finite-Lived Intangible Assets [Member] Payment Guarantee [Member] Payment Guarantee [Member] Financial Guarantee [Member] Financial Guarantee [Member] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] CENG [Member] CENG [Member] Represents a joint venture relating to a nuclear generation and operation business. Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] ATF [Member] ATF [Member] ATF [Member] Number Of Variable Interest Entities Consolidated Number Of Variable Interest Entities Consolidated The number of variable interest entities (VIEs) consolidated. Number of Variable Interest Entities not consolidated by equity holders Number Of Variable Interest Entities Not Consolidated The number of variable interest entities (VIEs) not consolidated. Guarantor Obligations, Current Carrying Value Guarantor Obligations, Current Carrying Value Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Due from Affiliates Due from Affiliates Guarantor Obligations, Maximum Exposure, Undiscounted Guarantor Obligations, Maximum Exposure, Undiscounted Cash Remitted To VIE Cash Remitted To VIE Cash Remitted To VIE Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] EEPF395Aug2020 [Member] EEPF395Aug2020 [Member] EEPF395Aug2020 [Member] [Member] EEPF346Aug2020 [Member] EEPF346Aug2020 [Member] EEPF346Aug2020 [Member] FMB400Mar2049 [Member] FMB400Mar2049 [Member] FMB400Mar2049 [Member] FMB345Jun2029 [Member] FMB345Jun2029 [Member] FMB345Jun2029 [Member] Medco170Sep2022 [Member] Medco170Sep2022 [Member] Medco170Sep2022 [Member] FMB350May2029 [Member] FMB350May2029 [Member] FMB350May2029 [Member] FMB414May2049 [Member] FMB414May2049 [Member] FMB414May2049 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Notes Payable, Other Payables [Member] Notes Payable, Other Payables [Member] Long-term Debt [Member] Long-term Debt [Member] First Mortgage Bonds [Member] First Mortgage Bonds [Member] Bonds that are backed by the first claim on the proceeds from the sale of a specific asset or set of assets in the event that the company is liquidated. Tax-exempt Money Market Funds [Member] Tax-exempt Money Market Funds [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Interest Rate Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Face Amount Debt Instrument, Face Amount Statement of Stockholders' Equity [Abstract] Common Stock, Dividends, Per Share, Declared Common Stock, Dividends, Per Share, Declared Antelope Valley [Member] Antelope Valley [Member] Antelope Valley is a wholly owned indirect subsidiary of EGR IV ExGen Renewables IV, LLC [Member] ExGen Renewables IV, LLC [Member] ExGen Renewables IV, LLC [Member] Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities Capacity of facility of company owned solar distribution generation facilities. Long-lived assets Net Assets Impairment of long-lived assets Derivative Contract [Domain] Summary of the derivative fair value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] Credit-Risk Related Contingent Credit- Risk Related Contingent Features [Table Text Block] Table format of information on the sources of credit risk exposure faced by the entity for all derivative instruments and detail of credit exposure by type of counterparty Fair Value of Derivatives with Credit- Risk Related Contingent Features [Table Text Block] [Table Text Block] Fair Value of Derivatives with Credit- Risk Related Contingent Features [Table Text Block] [Table Text Block] Fair Value of Derivatives with Credit- Risk Related Contingent Features [Table Text Block] [Table Text Block] Cash Collateral and Letters of Credit on Derivative Contracts [Table Text Block] Cash Collateral and Letters of Credit on Derivative Contracts [Table Text Block] Cash Collateral and Letters of Credit on Derivative Contracts [Table Text Block] Prior service costs Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Actuarial losses Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Other Comprehensive Income (Loss), Tax Other Comprehensive Income (Loss), Tax Change in unrealized gains (losses) on investments in unconsolidated affiliates Other Comprehensive Income Unrealized Gain Loss On Equity Investments Arising During Period Tax Tax effect of the change in unrealized gains and losses from equity investments held during the period being reported on. Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Supplemental Financial Information (All Registrants) Additional Financial Information Disclosure [Text Block] Retirement Benefits [Abstract] Retirement Benefits (All Registrants) Pension and Other Postretirement Benefits Disclosure [Text Block] Public Utility, Property, Plant and Equipment [Table] Public Utility, Property, Plant and Equipment [Table] Public Utility, Property, Plant and Equipment [Line Items] Public Utility, Property, Plant and Equipment [Line Items] Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes Balance Sheet Related Disclosures [Abstract] Implications of Potential Early Plant Retirement [Table] Implications of Potential Early Plant Retirement [Table] Implications of Potential Early Plant Retirement Mystic Generating Station [Member] Mystic Generating Station [Member] Mystic Generating Station [Member] Implications of Potential Early Plant Retirement [Line Items] Implications of Potential Early Plant Retirement [Line Items] [Line Items] for Implications of Potential Early Plant Retirement Materials and supplies inventory Inventory, Raw Materials, Gross Fuel inventory Energy Related Inventory, Other Fossil Fuel Completed plant, net Construction work in progress Construction in Progress, Gross Asset retirement obligation Asset Retirement Obligation Analysis and reconciliation of reportable segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Analysis and reconciliation of reportable segment revenues for Generation Revenue from External Customers by Geographic Areas [Table Text Block] Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Schedule Of Nuclear Decommissioning [Table] Schedule Of Nuclear Decommissioning [Line Items] Schedule Of Nuclear Decommissioning [Line Items] Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of Change in Asset Retirement Obligation [Table Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Equity Securities without Readily Determinable Fair Value, Amount Equity Securities without Readily Determinable Fair Value, Amount Segment Information (All Registrants) Segment Reporting Disclosure [Text Block] Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Unrecognized Tax Benefits Unrecognized Tax Benefits Aggregate fair value of derivatives with credit-risk-related contingent features Derivative Liability, Fair Value, Gross Liability Offsetting fair value of in-the-money contracts under master netting agreements Offsetting fair value of in-the-money contracts under master netting agreements Offsetting fair value of in-the-money contracts under master netting agreements - This amount represents the offsetting fair value of in-the-money derivative contracts under legally enforceable master netting agreements with the same counterparty, which reduces the amount of any liability for which a Registrant could potentially be required to post collateral. Contractual right of offset related to derivative assets Derivative Liability, Fair Value, Amount Offset Against Collateral Net liability position after contractual right of offset Net Asset Liability Position After Contractual Right Of Offset The net asset or liability position as of the balance sheet date after applying the contractual right of offset related to derivative instruments with credit-risk-related contingent features with the same counterparty under master netting agreements. Credit-risk-related contingent features stipulate that if the Company 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. Revenue from Contracts with Customers [Text Block] Revenue from Contract with Customer [Text Block] Other, Net [Abstract] Other Nonoperating Income (Expense) [Abstract] Decommissioning-Related Activities [Abstract] Gain Loss On Nuclear Decommissioning Trust Fund Investments [Abstract] Gain / loss on nuclear decommissioning trust fund investments abstract. Net realized income on NDT funds - Regulatory agreement units Realized Gain Loss Investment Income Nuclear Decommissioning Trust Funds Regulatory Accounting This item represents investment income and realized gains (losses) for the period as a result of selling marketable securities held in nuclear decommissioning trust funds and classified as trading securities. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement. Net realized income on NDT funds - Non-regulatory agreement units Realized Gain Loss Investment Income Nuclear Decommissioning Trust Funds Nonregulatory Accounting This item represents investment income and realized gains (losses) for the period as a result of selling marketable securities held in nuclear decommissioning trust funds classified as trading securities. Net unrealized (losses) gains on NDT funds - Regulatory agreement units Unrealized Gain Loss Nuclear Decommissioning Trust Funds Regulatory Accounting This item represents unrealized gains (losses) for the period as a result of holding marketable securities held in nuclear decommissioning trust funds and classified as trading securities. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement. Net unrealized (losses) gains on NDT funds - Non-regulatory agreement units Unrealized Gain Loss Nuclear Decommissioning Trust Funds Nonregulatory Accounting This item represents unrealized gains (losses) included in earnings for the period as a result of holding marketable securities held in nuclear decommissioning trust funds and classified as trading securities. Regulatory offset to NDT fund-related activities Regulatory Offset Nuclear Decommissioning Trust Fund Activity This item represents the contractual elimination of nuclear decommissioning trust fund-related activity, which may include realized income (losses), unrealized income (losses), asset retirement obligation accretion, asset retirement cost amortization, investment income and related income taxes. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement. Decommissioning-related activities Gain Loss Investment Income Nuclear Decommissioning Trust Funds This item represents the total investment income and realized and unrealized gains (losses) included in earnings for the period as a result of selling and holding marketable securities held in nuclear decommissioning trust funds and classified as trading securities. AFUDC - Equity Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Non-service net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Leases [Abstract] Supplemental Balance Sheet Information [Table] Other Deferred Debits and Other Assets [Member] Other Noncurrent Assets [Member] Other Current Liabilities [Member] Other Current Liabilities [Member] Other Deferred Credits and Other Liabilities [Member] Other Noncurrent Liabilities [Member] Other deferred debits and other assets Other current liabilities Other deferred credits and other liabilities Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Letters of Credit Financial Standby Letter of Credit [Member] Surety Bonds Surety Bond [Member] Financing trust guarantees Guarantee of Indebtedness of Others [Member] Guaranteed lease residual values Guarantee Obligations [Member] Lessor, Operating Lease, Term of Contract Regulatory Matters Completed Rate Cases [Table] Regulatory Matters Completed Rate Cases [Table] Regulatory Matters Completed Rate Cases [Table] Electric Distribution [Member] Electric Distribution [Member] Electricity [Member] Electricity [Member] Gas Distribution [Member] Gas Distribution [Member] Regulatory Matters Completed Rate Cases [Line Items] Regulatory Matters Completed Rate Cases [Line Items] [Line Items] for Regulatory Matters Completed Rate Cases [Table] Requested Revenue Requirement Increase (Decrease) Approved Revenue Requirement Increase (Decrease) Public Utilities, Approved Rate Increase (Decrease), Amount Approved Return on Equity, Percentage Schedule of Components of Lease Cost [Table] Schedule of Components of Lease Cost [Table] Schedule of Components of Lease Cost Schedule of Components of Lease Cost [Line Items] Schedule of Components of Lease Cost [Line Items] [Line Items] for Schedule of Components of Lease Cost Operating Lease Costs Operating Lease, Cost Variable Lease Costs Variable Lease, Cost Short-term Lease Costs Short-term Lease, Cost Total Lease Costs Lease, Cost Sublease Income Sublease Income Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term Operating Lease Weighted Average Discount Rate, Percent Operating Lease, Weighted Average Discount Rate, Percent Contract with Customer, Asset and Liability [Table Text Block] Contract with Customer, Asset and Liability [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Commitments And Contingencies Tables Disclosure [Table] Commitments And Contingencies Tables Disclosure [Table] Commitments And Contingencies Tables Disclosure [Line Items] Commitments And Contingencies Tables Disclosure [Line Items] Other Commitments Other Commitments [Table Text Block] Accrued environmental liabilities Schedule of Environmental Loss Contingencies by Site [Table Text Block] Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss [Abstract] Inventory, net Materials and Supplies Other current assets NDT funds Total noncurrent assets Assets, Noncurrent Accounts payable Accrued expenses Unamortized energy contract liabilities Total current liabilities Long-term debt Asset retirement obligations Unamortized energy contract liabilities Total noncurrent liabilities Total Deferred Credits And Other Liabilities Total deferred credits and other liabilities. Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Reported Value Measurement [Member] Reported Value Measurement [Member] Estimate of Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Financing Trusts [Member] Financing Trusts [Member] Financing Trusts represent nonconsolidated affiliates recorded as an investment on the Registrants' Consolidated Balance Sheets. Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Long-term debt (including amounts due within one year) Debt Instrument, Fair Value Disclosure Long-term debt to financing trust Spent Nuclear Fuel Obligation, Noncurrent Lessee, Finance and Operating Leases [Text Block] Lessee, Finance and Operating Leases [Text Block] The entire disclosure for finance and operating leases of lessee. Includes, but is not limited to, description of lessee's finance and operating leases and maturity analysis of finance and operating leases liability Lessor, Operating Leases [Text Block] Lessor, Operating Leases [Text Block] Fair Value Measurement Inputs and Valuation Techniques [Table] Economic Hedges [Member] Economic Hedges [Member] Economic Hedges [Member] Derivative [Member] Derivative [Member] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Discounted Cash Flow [Member] Valuation, Income Approach [Member] Option Model Valuation Technique [Member] Option Model Valuation Technique [Member] Option model approach valuation technique used to measure fair value. Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Derivative Asset, Fair Value, Amount Not Offset Against Collateral Derivative Asset, Fair Value, Amount Not Offset Against Collateral Fair Value Measurement Inputs and Valuation Techniques [Abstract] Forward power price assets Fair Value Inputs Forward Power Price Assets This element represents the forward power market price used to calculate the change in fair value of the derivative instrument. Forward gas price assets Fair Value Inputs Forward Gas Price Assets This element represents the forward power market price used to calculate the change in fair value of the derivative instrument. Derivative Asset (Liability) Net, Measurement Input Derivative Asset (Liability) Net, Measurement Input Forward heat rate Fair Value Inputs Forward Heat Rate This element represents the factor that is multiplied with the forward price of natural gas to calculate a forward power curve. Natural gas has greater liquidity tenor than power and is commonly used to calculate this curve. Fair Value Inputs Renewable Factor Fair Value Inputs Renewable Factor This element represents a factor to adjust an around the clock forward power price and quantity to be in line with an applicable renewable facility. Solar units generally produce more power in the summer days and wind units generally produce more power in the spring and fall evenings. Derivatives Fair Value Footnotes [Abstract] Derivatives Fair Value Footnotes [Abstract] Lessor, Lease, Description [Table] Lessor, Lease, Description [Table] Lessor, Lease, Description [Line Items] Lessor, Lease, Description [Line Items] Lessor, Operating Lease, Description Lessor, Operating Lease, Description Remaining lease terms Options to extend the term Lessor, Operating Lease, Option to Extend Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Interest Income (Expense), Nonoperating, Net Interest Income (Expense), Nonoperating, Net Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income Tax Expense (Benefit) Income Tax Expense (Benefit) Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Amortization of pension and other postretirement benefit plan items Tax benefit Reclassification from AOCI, Current Period, Tax Amounts reclassified from AOCI Income statement expense (pre-tax) Schedule of Other Operating Cost and Expense, by Component [Table Text Block] Implications of Potential Early Plant Retirement on Balance Sheet [Table Text Block] Implications of Potential Early Plant Retirement on Balance Sheet [Table Text Block] [Table Text Block] for Implications of Potential Early Plant Retirement on the Balance Sheet Cover page. Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] VIRGINIA VIRGINIA Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Junior Subordinated Debt [Member] Junior Subordinated Debt [Member] Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] All Exchanges [Domain] All Exchanges [Domain] CHICAGO STOCK EXCHANGE, INC [Member] CHICAGO STOCK EXCHANGE, INC [Member] NEW YORK STOCK EXCHANGE, INC. [Member] NEW YORK STOCK EXCHANGE, INC. [Member] Document Quarterly Report Document Quarterly Report Document Type Document Type Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Tax Identification Number Entity Tax Identification Number Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Central Index Key Entity Central Index Key Amendment Flag Amendment Flag Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Plan, Defined Benefit [Member] Pension Plan [Member] Other Postretirement Benefit Plan, Defined Benefit [Member] Other Postretirement Benefits Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Increase (Decrease) in Obligation, Pension Benefits Increase (Decrease) in Obligation, Pension Benefits Increase (Decrease) in Obligation, Other Postretirement Benefits Increase (Decrease) in Obligation, Other Postretirement Benefits Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax Defined Benefit Plan Amounts Recognized In Regulatory Assets Before Tax Defined Benefit Plan Amounts Recognized In Regulatory Assets Before Tax The aggregate net gain or loss and net prior service cost or credit recognized in regulatory assets, including amounts arising during the period and reclassification adjustments of regulatory assets as a result of being recognized as components of net periodic benefit cost for the period. Defined Benefit Plan Amounts Recognized In Regulatory Liabilities Before Tax Defined Benefit Plan Amounts Recognized In Regulatory Liabilities Before Tax Increase in regulatory liabilities due to updated valuation received by Exelon for its legacy pension and other postretirement benefit obligations. Expected return on assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Not Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument, Trading [Member] Collateral [Member] Collateral [Member] Collateral [Member] Netting [Member] Netting [Member] Netting [Member] Commodity Contract [Member] Commodity Contract [Member] Mark-to-market derivatives assets Total mark-to-market derivative assets Derivative Liability, Current Derivative Liability, Noncurrent Total mark-to-market derivative liabilities Total mark-to-market derivative net assets (liabilities) Derivative, Fair Value, Net Derivative Liability, Fair Value, Amount Offset Against Collateral Schedule of Defined Benefit Plans Disclosures [Table] Pension and other post retirement benefit [Member] Pension and other post retirement benefit [Member] Pension and other post retirement benefit [Member] Pension and Other Postretirement Benefits Cost (Reversal of Cost) Operating Lease, Lease Income [Abstract] Schedule of Operating Lease, Lease Income [Table] Schedule of Operating Lease, Lease Income [Table] Schedule of Operating Lease, Lease Income Components Schedule of Operating Lease, Lease Income [Line Items] Schedule of Operating Lease, Lease Income [Line Items] [Line Items] for Schedule of Operating Lease, Lease Income Components Operating Lease Income Operating Lease, Lease Income, Lease Payments Variable Lease Income Operating Lease, Variable Lease Income Nuclear Decommissioning (Exelon and Generation) Asset Retirement Obligation Disclosure [Text Block] Commercial Agreement Variable Interest Entities [Member] Commercial Agreement Variable Interest Entities [Member] Equity Investment VIE [Member] Equity Investment VIE [Member] Equity Investment VIE [Member] Carrying amount of equity method investments Contract intangible asset Total assets Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets Total liabilities Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities Exelon's ownership interest in VIE Investments In Nonconsolidated Variable Interest Entities This element represents the total investments in variable interest entities as of the balance sheet date. Other ownership interests in VIE Other Nonconsolidated Variable Interest Entity Ownership Interests The carrying value of other ownership interests as of the balance sheet date. Registrants' maximum exposure to loss Regulatory Matters (All Registrants) Public Utilities Disclosure [Text Block] Unrealized Gain (Loss) on Derivatives Regulatory Matters Additional Narrative Information [Table] Regulatory Matters Additional Narrative Information [Table] Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Energy Efficiency Costs [Member] Energy Efficiency Costs [Member] Energy Efficiency Costs [Member] Electric Distribution Formula Rate Annual Reconciliations [Member] Electric Distribution Formula Rate Annual Reconciliations [Member] Electric Distribution Formula Rate Annual Reconciliations [Member] Under Recovered Energy and Natural Gas Costs [Member] Under Recovered Energy and Natural Gas Costs [Member] Represents the under-recovered (regulatory asset) purchased power and/or gas supply related costs recoverable from customers. An under recovery means that the actual costs of electricity or natural gas realized by the regulated utility were more than the rates charged to customers during the period and are recoverable from customers. DC PLUG Charge [Member] DC PLUG Charge [Member] DC PLUG Charge [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Generation commodities and services Energy Commodities and Service [Member] License and Service [Member] License and Service [Member] Conowingo [Member] Conowingo [Member] Conowingo [Member] Deferred Income Tax Charge [Member] Deferred Income Tax Charge [Member] Removal Costs [Member] Removal Costs [Member] Zero Emission Standard [Member] Zero Emission Standard [Member] Zero Emission Standard [Member] Valuation Adjustment [Axis] Valuation Adjustment [Axis] ValuationAdjustment [Domain] ValuationAdjustment [Domain] One-Time Revenue Adjustment [Member] One-Time Revenue Adjustment [Member] One-Time Revenue Adjustment [Member] Regulatory Matters Additional Narrative Information [Line Items] Regulatory Matters Additional Narrative Information [Line Items] Regulatory Matters Additional Narrative Information [Line Items] Public Utilities, Requested Equity Capital Structure, Percentage Revenue Payments to Acquire Property, Plant, and Equipment Amount of Impairment to Carrying Amount of Regulatory Assets Amount of Impairment to Carrying Amount of Regulatory Assets Increase (Decrease) in Regulatory Assets Increase (Decrease) in Other Regulatory Assets Public Utilities, Requested Return on Equity, Percentage Increase (Decrease) in Regulatory Liabilities Increase (Decrease) in Regulatory Liabilities Revenue from Contract with Customer, Including Assessed Tax Revenue from Contract with Customer, Including Assessed Tax Jointly Owned Utility Plant, Proportionate Ownership Interest, percentage Competitive businesses other revenues License Costs Cost of Goods and Services Sold Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract] Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Table] Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Table] Schedule of Lessor, Operating Lease, Payments to be Received, Maturity Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items] Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items] [Line Items] for Schedule of Lessor, Operating Lease, Payments to be Received, Maturity 2019 Lessor, Operating Lease, Payments to be Received, Remainder of Fiscal Year 2020 Lessor, Operating Lease, Payments to be Received, Next Twelve Months 2021 Lessor, Operating Lease, Payments to be Received, Two Years 2022 Lessor, Operating Lease, Payments to be Received, Three Years 2023 Lessor, Operating Lease, Payments to be Received, Four Years Remaining years Lessor, Operating Lease, Payments to be Received, Thereafter Total Lessor, Operating Lease, Payments to be Received Income Taxes (All Registrants) Income Tax Disclosure [Text Block] DOE Project Financing, 2.82% January 5, 2037 [Member] DOE Project Financing, 2.82% January 5, 2037 [Member] ExGenRenewablesIVNov2024 [Member] ExGenRenewablesIVNov2024 [Member] ExGenRenewablesIVNov2024 [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Line of Credit [Member] Line of Credit [Member] Non Recourse Debt [Member] Non Recourse Debt [Member] Short-term Bank Loans and Notes Payable Short-term Bank Loans and Notes Payable Debt Instrument, Interest Rate Terms Debt Instrument, Interest Rate Terms Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Long-term Line of Credit Long-term Line of Credit Non-Recourse Debt Non-Recourse Debt Regulatory Matters Pending Rate Cases [Table] Regulatory Matters Pending Rate Cases [Table] Regulatory Matters Pending Rate Cases [Table] Jurisdiction [Axis] Jurisdiction [Axis] Statutory Accounting Practices, Jurisdiction [Domain] Statutory Accounting Practices, Jurisdiction [Domain] MARYLAND MARYLAND DISTRICT OF COLUMBIA DISTRICT OF COLUMBIA Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Forecast [Member] Forecast [Member] Regulatory Matters Pending Rate Cases [Line Items] Regulatory Matters Pending Rate Cases [Line Items] Line Items for Regulatory Matters Pending Rate Cases [Table] Requested Revenue Requirement Increase (Decrease), Amended Requested Return on Equity, Percentage Requested Return on Distribution Rate Base, Percentage Asset Impairment Charges [Text Block] Asset Impairment Charges [Text Block] Schedule of Segment Reporting Information, by Segment [Table] Oil and Gas, Purchased [Member] Oil and Gas, Purchased [Member] Electricity, US Regulated Electricity, US Regulated [Member] Electricity, Generation [Member] Electricity, Generation [Member] Natural Gas, US Regulated Natural Gas, US Regulated [Member] Service, Other [Member] Service, Other [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Corporate and Other [Member] Corporate and Other [Member] Generation Mid Atlantic [Member] Generation Mid Atlantic [Member] Represents the Mid-Atlantic segment of Exelon Corporation and Exelon Generation Company, LLC. Generation Midwest [Member] Generation Midwest [Member] Represents the Midwest segment of Exelon Corporation and Exelon Generation Company, LLC. Operating Segments [Member] Operating Segments [Member] Intersegment Eliminations [Member] Intersegment Eliminations [Member] PotomacElectricPowerCompanyAffiliate [Member] PotomacElectricPowerCompanyAffiliate [Member] PotomacElectricPowerCompanyAffiliate [Member] DelmarvaPowerandLightCompanyAffiliate [Member] DelmarvaPowerandLightCompanyAffiliate [Member] DelmarvaPowerandLightCompanyAffiliate [Member] AtlanticCityElectricCompanyAffiliate [Member] AtlanticCityElectricCompanyAffiliate [Member] AtlanticCityElectricCompanyAffiliate [Member] Revenue from Contract with Customer, Including Assessed Tax Revenues Revenues Operating revenues from affiliates Revenue from Related Parties Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Operating Expenses Operating Expenses Interest Revenue (Expense), Net Interest Revenue (Expense), Net Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income taxes Net income (loss) Assets Schedule of Energy Efficiency Formula Rate Updates [Table] Schedule of Energy Efficiency Formula Rate Updates [Table] Schedule of Energy Efficiency Formula Rate Updates [Table] Schedule of Energy Efficiency Formula Rate Updates [Line Items] Schedule of Energy Efficiency Formula Rate Updates [Line Items] [Line Items] for Schedule of Energy Efficiency Formula Rate Updates [Table] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Revenue from Contract with Customer [Member] Contracts with Customers [Member] Contracts with Customers [Member] Generation New York [Member] Generation New York [Member] Generation ERCOT [Member] Generation ERCOT [Member] Generation Other Regions [Member] Generation Other Regions [Member] Generation Reportable Segments Total [Member] Generation Reportable Segments Total [Member] Generation Natural Gas [Member] Generation Natural Gas [Member] Generation Natural Gas [Member] Generation All Other Segments [Member] Generation All Other Segments [Member] Operating segments that do not meet the quantitative thresholds and thus are not classified as reportable segments for which there is an accounting requirement to report separate financial information on those components in the entity's financial statements. Unrealized Gain (Loss) on Securities Unrealized Gain (Loss) on Securities Early Plant Retirements (Exelon and Generation) Implications Of Potential Early Retirement Disclosure [Text Block] implications of potential early retirement disclosure [Text Block] Public Utilities General Disclosures [Table Text Block] Public Utilities General Disclosures [Table Text Block] Significant Accounting Policies [Text Block] Significant Accounting Policies [Text Block] Business Description [Text Block] Business Description and Basis of Presentation [Text Block] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] VIE - Assets and Liabilities of VIEs which Creditors or Beneficiaries have no Recourse [Table Text Block] Variable Interest Entity - Assets and Liabilities of Variable Interest Entity which Creditors or Beneficiaries have no Recourse [Table Text Block] Variable Interest Entity Disclosure - Summary of Unconsolidated Variable Interest Entity - Assets and Liabilities of Variable Interest Entity which Creditors or Beneficiaries have no Recourse [Table Text Block] VIE - Summary of Unconsolidated VIEs [Table Text Block] Variable Interest Entity Disclosure - Summary of Unconsolidated Variable Interest Entity [Table Text Block] Variable Interest Entity Disclosure - Summary of Unconsolidated Variable Interest Entity [Table Text Block] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Atlantic City Electric Co Affiliate [Member] Atlantic City Electric Co Affiliate [Member] Atlantic City Electric Co Affiliate [Member] Regulation Status [Axis] Regulation Status [Axis] Regulated and Unregulated Operation [Domain] Regulated and Unregulated Operation [Domain] Rate-Regulated Electric Revenues [Member] Rate-Regulated Electric Revenues [Member] Rate-Regulated Electric Revenues [Member] Rate-Regulated Natural Gas Revenues [Member] Rate-Regulated Natural Gas Revenues [Member] Rate-Regulated Natural Gas Revenues [Member] Regulated Operation [Member] Regulated Operation [Member] Other Regulated Revenue [Member] Other Regulated Revenue [Member] Other Regulated Revenue [Member] Residential [Member] Residential [Member] Residential [Member] Small Commercial & Industrial [Member] Small Commercial & Industrial [Member] Small Commercial & Industrial [Member] Large Commercial & Industrial [Member] Large Commercial & Industrial [Member] Large Commercial & Industrial [Member] Public Authorities & Electric Railroads [Member] Public Authorities & Electric Railroads [Member] Public Authorities & Electric Railroads [Member] Transportation [Member] Transportation [Member] Transportation [Member] Revenue, Major Customer [Line Items] Revenue, Major Customer [Line Items] Revenue from Related Parties Revenue Net Of Purchase Power And Fuel From External Customers Amount of revenues net of purchased power and fuel expense from external customers. Intersegment Revenue Net Of Purchase Power And Fuel Segment Reporting Information, Intersegment Revenue Net of Purchased Power and Fuel Expense Revenue Net of Purchase Power And Fuel Amount of total revenues net of purchased power and fuel expense for Generation Nuclear Fuel Amortization Debt and Credit Agreements (All Registrants) Debt Disclosure [Text Block] Calculation of Net Periodic Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Allocated Portion of Pension and Postretirement Benefit Costs Schedule of Costs of Retirement Plans [Table Text Block] Defined Contribution Savings Plans Defined Contribution Plan Disclosures [Table Text Block] Rate-regulated utility revenues Public Utilities [Member] Operating revenues Revenues [Abstract] Revenues from alternative revenue programs Regulated Operating Revenue Total operating revenues Operating expenses Costs and Expenses [Abstract] Purchased power and/or fuel Cost, Direct Material Purchased power and/or fuel from affiliates Related Party Transaction, Purchases from Related Party Operating and maintenance Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses Operating and maintenance from affiliates Related Party Transaction, Expenses from Transactions with Related Party Depreciation and amortization Cost, Depreciation and Amortization Taxes other than income Taxes, Miscellaneous Total operating expenses Costs and Expenses Gain on sales of assets and businesses Gain (Loss) on Disposition of Other Assets Operating income Operating Income (Loss) Other income and (deductions) Nonoperating Income (Expense) [Abstract] Interest expense, net Interest Expense Interest expense to affiliates Interest Expense, Related Party Other, net Other Nonoperating Income (Expense) Total other income and (deductions) Nonoperating Income (Expense) Income before income taxes Equity in losses of unconsolidated affiliates Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Net income Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income (loss) attributable to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Net income attributable to membership interest Net Income (Loss) Attributable to Parent Other comprehensive (loss) income, net of income taxes Other Comprehensive Income (Loss), Net of Tax [Abstract] Prior service benefit reclassified to periodic benefit cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Actuarial loss reclassified to periodic benefit cost Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Pension and non-pension postretirement benefit plan valuation adjustment Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Unrealized (loss) gain on cash flow hedges Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized (loss) gain on investments in unconsolidated affiliates Other Comprehensive Income Unrealized Income Loss On Equity Investments Arising During Period Net Of Tax Change in accumulated income and losses from certain equity investments during the period being reported on, net of tax. Unrealized gain (loss) on foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to common shareholders/membership interest Comprehensive Income (Loss), Net of Tax, Attributable to Parent Average shares of common stock outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic average shares of common stock outstanding Weighted Average Number of Shares Outstanding, Basic Assumed exercise and/or distributions of stock-based awards Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted average shares of common stock outstanding Weighted Average Number of Shares Outstanding, Diluted Earnings per average common share: Earnings Per Share, Basic and Diluted [Abstract] Basic earnings per average common share Earnings Per Share, Basic Diluted earnings per average common share Earnings Per Share, Diluted Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Change in Contract with Customer, Asset and Liability [Table] Change in Contract with Customer, Asset and Liability [Table] Change in Contract with Customer, Asset and Liability [Table] Change in Contract with Customer, Asset and Liability [Line Items] Change in Contract with Customer, Asset and Liability [Line Items] [Line Items] for Change in Contract with Customer, Asset and Liability [Table] Contract Assets Contract with Customer, Asset, Net, Current Contract Liabilities Contract with Customer, Liability, Current Consideration (received) due, contract assets Contract with Customer, Asset, Reclassified to Receivable Consideration received (due), contract liabilities Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Modification of Contract Revenues recognized, contract assets Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress Revenues recognized, contract liabilities Contract with Customer, Liability, Revenue Recognized Taxes Other Than Income Schedule Of Taxes Excluding Income And Excise Taxes [Table Text Block] This element may be used to capture the table showing the different components of taxes excluding income and excise taxes. Schedule of Other Nonoperating Income, by Component Schedule of Other Nonoperating Income, by Component [Table Text Block] Cash Flow Supplemental Disclosures Cash Flow, Supplemental Disclosures [Text Block] Supplemental Balance Sheet Disclosures Supplemental Balance Sheet Disclosures [Text Block] Asset Retirement Obligation Roll Forward Analysis [Table] Asset Retirement Obligation Roll Forward Analysis [Table] A table for the reconciliation of the nuclear decommissioning asset retirement obligation from the beginning of a period to the end of a period. Nuclear Decommissioning Asset Retirement Obligation [Member] Nuclear Decommissioning Asset Retirement Obligation [Member] Asset Retirement Obligation Roll Forward Analysis [Line Items] Asset Retirement Obligation Roll Forward Analysis [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Nuclear decommissioning ARO, beginning balance Accretion expense Costs incurred related to decommissioning plants Asset Retirement Obligation, Liabilities Incurred Nuclear decommissioning ARO, ending balance Current portion of ARO Asset Retirement Obligation, Current Proprietary Trading Activities Gain Loss By Income Statement Location [Axis] Proprietary Trading Activities Gain Loss By Income Statement Location [Axis] The income statement location that the gain/loss on proprietary trading activities could be reported under. Proprietary Trading Activities Income Location [Domain] Proprietary Trading Activities Income Location [Domain] The income statement line descriptions that the gain/loss on proprietary trading activities could be reported under. Savings Plan Matching Contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Fair Value of Financial Liabilities Recorded at Amortized Cost Fair Value, by Balance Sheet Grouping [Table Text Block] Assets and liabilities measured and recorded at fair value on recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Text Block] This element represents, for the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table Text Block] Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis, valuation technique Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques [Table Text Block] Mergers, Acquisitions and Dispositions Disclosures [Text Block] Mergers, Acquisitions and Dispositions Disclosures [Text Block] Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table] Summarization of information required and determined to be provided for purposes of reconciling beginning and ending balances of fair value measurements of assets and liabilities using significant unobservable inputs (Level 3). Such reconciliation, separately presenting changes during the period, at a minimum, may include: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Other Investments [Member] Other Investments [Member] Consolidation, Eliminations [Member] Consolidation, Eliminations [Member] Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Total realized / unrealized gains (losses) Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss [Abstract] This element represents total gains or losses for the period (realized and unrealized), arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3). Included in net income Included in noncurrent payables to affiliates Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates. Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable This element represents total gains or losses for the period (realized and unrealized), arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in a payable for nuclear power station decommissioning. Included in regulatory assets Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets Change in collateral Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral Fair value measurement with unobservable inputs reconciliation recurring basis asset liability gain loss change in collateral. Purchases, sales, issuances and settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract] Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract] Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease) Realized Investment Gains (Losses) Realized Investment Gains (Losses) Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of: Amortization of Prior Service Cost (Benefit) and Actuarial Loss [Abstract] Amortization of Prior Service Cost (Benefit) and Actuarial Loss [Abstract] Prior service cost (benefit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Settlement charges Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Net periodic benefit cost Components of Lease Cost [Table Text Block] Lease, Cost [Table Text Block] Supplemental Balance Sheet Information Related to Lessee Right-of-Use Assets and Lease Liabilities [Table Text Block] Supplemental Balance Sheet Information Related to Operating and Finance Lease Right-of-Use Assets and Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Lessee, Operating Lease, Liability, Maturity [Table Text Block] Schedule of Future Minimum Lease Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Supplemental Cash Flow Information Related to Leases [Table Text Block] Schedule of Supplemental Cash Flow Information Related to Leases [Table Text Block] Schedule of Supplemental Cash Flow Information Related to Leases Components of Operating Lease Income [Table Text Block] Operating Lease, Lease Income [Table Text Block] Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block] Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block]