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Fair Value of Financial Assets and Liabilities - Fair Value Measurement of Assets and Liabilities, Recurring (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 2 $ 2  
Derivative Asset, Notional Amount 1,043 724  
Derivative, Notional Amount 6,879 6,668  
Unrealized Gain (Loss) on Investments 186 0 $ 0
Margin Deposit Assets 209 511  
Market-to-market derivative liabilities, current 295 247  
Derivative Liability, Noncurrent 473 393  
Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 409 373  
Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 59 110  
Nuclear Decommissioning Trust Fund Investments [Member] | Maturity Less than 30 Days [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Cash 116 90  
Other assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 53 177  
Nuclear Decommissioning Trust Fund Investments [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Financial Instruments Sold, Not yet Purchased, Corporate Debt (62) (48)  
Fair Value Net Assets Liabilities Excluded From Nuclear Decommissioning Trust Fund Investments 181 147  
Derivative, Notional Amount 104 99  
Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 686 639  
Deferred purchase price 639    
Assets, Fair Value Disclosure 17,776 15,584  
Deferred Compensation Liability, Current and Noncurrent (145) (147)  
Total liabilities (910) (763)  
Fair Value, Net Asset (Liability) 16,866 14,821  
Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (765) (616)  
Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (4,265) (5,154)  
Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (25) (49)  
Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 3,525 4,587  
Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 14,780 13,500  
Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 305 452  
Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 7,525 6,542  
Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4,926 4,735  
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,770 1,678  
Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,997 1,939  
Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 56 42  
Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 101 90  
Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,002 986  
Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 841 762  
Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 504 402  
Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 679 607  
Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 283 262  
Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 60 50  
Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 91 81  
Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 11 12  
Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 121 119  
Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 195    
Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,193 1,183  
Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 4,258 4,744  
Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 44 97  
Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (3,109) (3,658)  
Fair Value, Inputs, Level 1 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net (67) 163  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 686 639  
Deferred purchase price 0    
Assets, Fair Value Disclosure 7,137 6,156  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (142) 0  
Fair Value, Net Asset (Liability) 6,995 6,156  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (142) 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (682) (1,071)  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 540 1,071  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 5,967 5,526  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 210 365  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 3,886 3,353  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,871 1,808  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,871 1,808  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 151 131  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 60 50  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 91 81  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 195    
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 138 (140)  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 745 768  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (607) (908)  
Fair Value, Inputs, Level 2 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net 321 551  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 639    
Assets, Fair Value Disclosure 5,052 4,061  
Deferred Compensation Liability, Current and Noncurrent (145) (147)  
Total liabilities (176) (322)  
Fair Value, Net Asset (Liability) 4,876 3,739  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (31) (175)  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (1,928) (2,855)  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (21) (34)  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 1,918 2,714  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 3,981 3,605  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 95 87  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 2,077 1,801  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,809 1,717  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,485 1,421  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 126 131  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 56 42  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 101 90  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 41 33  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 98 90  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 11 12  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 87 78  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 334 366  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,914 2,491  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 17 37  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (1,597) (2,162)  
Fair Value, Inputs, Level 3 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net 162 214  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 0    
Assets, Fair Value Disclosure 1,252 1,509  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (592) (441)  
Fair Value, Net Asset (Liability) 660 1,068  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (592) (441)  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (1,655) (1,228)  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (4) (15)  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 1,067 802  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 497 511  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 285 257  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 285 257  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 212 254  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 721 957  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,599 1,485  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 27 60  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (905) (588)  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 0    
Assets, Fair Value Disclosure 4,335 3,858  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 4,335 3,858  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4,335 3,858  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,562 1,388  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 961 953  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 961 953  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 629 508  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 504 402  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 679 607  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Exelon Generation Co L L C [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value 2 2  
Derivative Asset, Notional Amount 1,043 724  
Unrealized Gain (Loss) on Investments 186 0 $ 0
Margin Deposit Assets 209 511  
Market-to-market derivative liabilities, current 262 215  
Derivative Liability, Noncurrent 205 123  
Exelon Generation Co L L C [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 171 177  
Exelon Generation Co L L C [Member] | Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 20 58  
Exelon Generation Co L L C [Member] | Nuclear Decommissioning Trust Fund Investments [Member] | Maturity Less than 30 Days [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Cash 116 90  
Exelon Generation Co L L C [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Financial Instruments Sold, Not yet Purchased, Corporate Debt (62) (48)  
Fair Value Net Assets Liabilities Excluded From Nuclear Decommissioning Trust Fund Investments 181 147  
Derivative, Notional Amount 104 99  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 124 214  
Deferred purchase price 639    
Assets, Fair Value Disclosure 16,992 14,951  
Deferred Compensation Liability, Current and Noncurrent (42) (41)  
Total liabilities (506) (356)  
Fair Value, Net Asset (Liability) 16,486 14,595  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (464) (315)  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (3,964) (4,853)  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (25) (49)  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 3,525 4,587  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 14,780 13,500  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 305 452  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 7,525 6,542  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4,926 4,735  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,770 1,678  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,997 1,939  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 56 42  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 101 90  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,002 986  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 841 762  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 504 402  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 679 607  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 61 54  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4 4  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 29 25  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 28 25  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 195    
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,193 1,183  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 4,258 4,744  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 44 97  
Exelon Generation Co L L C [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (3,109) (3,658)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net (67) 163  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 124 214  
Deferred purchase price 0    
Assets, Fair Value Disclosure 6,457 5,629  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (142) 0  
Fair Value, Net Asset (Liability) 6,315 5,629  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (142) 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (682) (1,071)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 540 1,071  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 5,967 5,526  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 210 365  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 3,886 3,353  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,871 1,808  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,871 1,808  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 33 29  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4 4  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 29 25  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 195    
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 138 (140)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 745 768  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (607) (908)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net 321 551  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 639    
Assets, Fair Value Disclosure 4,982 3,996  
Deferred Compensation Liability, Current and Noncurrent (42) (41)  
Total liabilities (73) (216)  
Fair Value, Net Asset (Liability) 4,909 3,780  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (31) (175)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (1,928) (2,855)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (21) (34)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 1,918 2,714  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 3,981 3,605  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 95 87  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 2,077 1,801  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,809 1,717  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,485 1,421  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 126 131  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 56 42  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 101 90  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 41 33  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 28 25  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 28 25  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 334 366  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,914 2,491  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 17 37  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (1,597) (2,162)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Fair Value, Amount Offset Against Collateral, Net 162 214  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 0    
Assets, Fair Value Disclosure 1,218 1,468  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (291) (140)  
Fair Value, Net Asset (Liability) 927 1,328  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (291) (140)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (1,354) (927)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (4) (15)  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 1,067 802  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 497 511  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 285 257  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 285 257  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 212 254  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 721 957  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 1,599 1,485  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 27 60  
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset (905) (588)  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Deferred purchase price 0    
Assets, Fair Value Disclosure 4,335 3,858  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 4,335 3,858  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 4,335 3,858  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents NDT [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities Nuclear Decommissioning Trust Fund      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 1,562 1,388  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 961 953  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | State and municipal debt [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Other Fixed Income [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 961 953  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Credit [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 629 508  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Private Equity Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 504 402  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Real Estate Funds [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 679 607  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0    
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Commodity Derivative Assets [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Economic Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Proprietary Trading [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Exelon Generation Co L L C [Member] | Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member] | Effects of Netting and Allocation of Collateral [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Commonwealth Edison Co [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Market-to-market derivative liabilities, current 33 32  
Derivative Liability, Noncurrent 268 269  
Commonwealth Edison Co [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 83 90  
Commonwealth Edison Co [Member] | Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 37 33  
Commonwealth Edison Co [Member] | Other assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 43 163  
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 285 280  
Assets, Fair Value Disclosure 285 280  
Total mark-to-market derivative liabilities (301) (301)  
Deferred Compensation Liability, Current and Noncurrent (8) (8)  
Total liabilities (309) (309)  
Fair Value, Net Asset (Liability) (24) (29)  
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 285 280  
Assets, Fair Value Disclosure 285 280  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 285 280  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (8) (8)  
Total liabilities (8) (8)  
Fair Value, Net Asset (Liability) (8) (8)  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Market-to-market derivative liabilities, current 33 32  
Derivative Liability, Noncurrent 268 269  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Total mark-to-market derivative liabilities (301) (301)  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (301) (301)  
Fair Value, Net Asset (Liability) (301) (301)  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
PECO Energy Co [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
PECO Energy Co [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 18 12  
PECO Energy Co [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 8 15  
Assets, Fair Value Disclosure 30 34  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (9) (9)  
Total liabilities (9) (9)  
Fair Value, Net Asset (Liability) 21 25  
PECO Energy Co [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 22 19  
PECO Energy Co [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 9 8  
PECO Energy Co [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 13 11  
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 8 15  
Assets, Fair Value Disclosure 17 23  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 17 23  
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 9 8  
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 9 8  
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 13 11  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (9) (9)  
Total liabilities (9) (9)  
Fair Value, Net Asset (Liability) 4 2  
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 13 11  
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 13 11  
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Baltimore Gas and Electric Company [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 24 24  
Baltimore Gas and Electric Company [Member] | Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 1 1  
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 120 0  
Assets, Fair Value Disclosure 130 8  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (5) (5)  
Total liabilities (5) (5)  
Fair Value, Net Asset (Liability) 125 3  
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 10 8  
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 10 8  
Baltimore Gas and Electric Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 120 0  
Assets, Fair Value Disclosure 130 8  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 130 8  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 10 8  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 10 8  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (5) (5)  
Total liabilities (5) (5)  
Fair Value, Net Asset (Liability) (5) (5)  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 74 57  
Pepco Holdings LLC [Member] | Other assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 10 14  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 86 124  
Assets, Fair Value Disclosure 226 259  
Deferred Compensation Liability, Current and Noncurrent (17) (19)  
Total liabilities (17) (19)  
Fair Value, Net Asset (Liability) 209 240  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 140 135  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 55 44  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 14 14  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 11 12  
Pepco Holdings LLC [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 60 65  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 86 124  
Assets, Fair Value Disclosure 155 182  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 155 182  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 69 58  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 55 44  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 14 14  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 37 36  
Deferred Compensation Liability, Current and Noncurrent (17) (19)  
Total liabilities (17) (19)  
Fair Value, Net Asset (Liability) 20 17  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 37 36  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 11 12  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 26 24  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 34 41  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 34 41  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Potomac Electric Power Company [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Potomac Electric Power Company [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 30 29  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 35 34  
Assets, Fair Value Disclosure 150 144  
Deferred Compensation Liability, Current and Noncurrent (2) (2)  
Total liabilities (2) (2)  
Fair Value, Net Asset (Liability) 148 142  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 115 110  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 53 43  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 2 2  
Potomac Electric Power Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 60 65  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 35 34  
Assets, Fair Value Disclosure 88 77  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 88 77  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 53 43  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 53 43  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 28 26  
Deferred Compensation Liability, Current and Noncurrent (2) (2)  
Total liabilities (2) (2)  
Fair Value, Net Asset (Liability) 26 24  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 28 26  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 2 2  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 26 24  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 34 41  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 34 41  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 34 41  
Delmarva Power & Light Company [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Delmarva Power & Light Company [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 15 13  
Delmarva Power & Light Company [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Delmarva Power & Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Unrealized Gain (Loss) on Investments 0    
Atlantic City Electric Company [Member] | Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 17 12  
Atlantic City Electric Company [Member] | Other assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 10 14  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 13 16  
Assets, Fair Value Disclosure 13 16  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 13 16  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 13 16  
Assets, Fair Value Disclosure 13 16  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 13 16  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 0 0  
Assets, Fair Value Disclosure 0 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 0 0  
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure $ 0 $ 0