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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, 2022
Dec. 31, 2021
Dec. 31, 2020
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Derivative, Notional Amount $ 3,434 $ 3,481  
Unrealized Gain (Loss) on Investments (16) (160) $ 186
Market-to-market derivative liabilities, current 8 18  
Derivative Liability, Noncurrent 83 201  
Cash and Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 345 464  
Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 81 49  
Other assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 117 44  
Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 664 524  
Assets, Fair Value Disclosure 891 752  
Deferred Compensation Liability, Current and Noncurrent (75) (131)  
Total liabilities (166) (350)  
Fair Value, Net Asset (Liability) 725 402  
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) 0  
Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (4) 0  
Fair Value, Recurring [Member] | Interest Rate Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (7) 0  
Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (84) (219)  
Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 216 228  
Fair Value, Recurring [Member] | Cash Equivalents [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 62 60  
Fair Value, Recurring [Member] | Mutual Fund [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 49 60  
Fair Value, Recurring [Member] | Fixed Income Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 7 10  
Fair Value, Recurring [Member] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 98 98  
Fair Value, Recurring [Member] | Designated as Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 6 0  
Fair Value, Recurring [Member] | Economic Hedges [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 5 0  
Fair Value, Recurring [Member] | Interest Rate Derivative Assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 11 0  
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 664 524  
Assets, Fair Value Disclosure 775 644  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 775 644  
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 0 0  
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Domain]      
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] | Interest Rate Derivative Liabilities [Domain]      
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] | Mark-to-Market Derivative Liabilities [Domain]      
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] | Rabbi Trust Investments [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 111 120  
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 62 60  
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 49 60  
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] | Designated as Hedging Instrument [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] | Economic Hedges [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] | Interest Rate Derivative Assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
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 76 71  
Deferred Compensation Liability, Current and Noncurrent (75) (131)  
Total liabilities (82) (131)  
Fair Value, Net Asset (Liability) (6) (60)  
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 (3) 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (4) 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Interest Rate Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (7) 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 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 65 71  
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 7 10  
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 58 61  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Designated as Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 6 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 5 0  
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Interest Rate Derivative Assets      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 11 0  
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 40 37  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (84) (219)  
Fair Value, Net Asset (Liability) (44) (182)  
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 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Interest Rate Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Domain]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Total mark-to-market derivative liabilities (84) (219)  
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 40 37  
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 40 37  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Designated as Hedging Instrument [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Economic Hedges [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Derivative Asset 0 0  
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Interest Rate Derivative Assets      
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]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 0  
Commonwealth Edison Co [Member]      
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]      
Market-to-market derivative liabilities, current 5 18  
Derivative Liability, Noncurrent 79 201  
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 42 105  
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 77 42  
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 117 43  
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 392 237  
Derivative Asset 0    
Assets, Fair Value Disclosure 392 237  
Total mark-to-market derivative liabilities (84) (219)  
Deferred Compensation Liability, Current and Noncurrent (8) (10)  
Total liabilities (92) (229)  
Fair Value, Net Asset (Liability) 300 8  
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 392 237  
Assets, Fair Value Disclosure 392 237  
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) 392 237  
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) (10)  
Total liabilities (8) (10)  
Fair Value, Net Asset (Liability) (8) (10)  
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 5 18  
Derivative Liability, Noncurrent 79 201  
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 (84) (219)  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities (84) (219)  
Fair Value, Net Asset (Liability) (84) (219)  
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  
Commonwealth Edison Co [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]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 58 35  
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 10 9  
Assets, Fair Value Disclosure 32 36  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (7) (9)  
Total liabilities (7) (9)  
Fair Value, Net Asset (Liability) 25 27  
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 27  
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 7 11  
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 15 16  
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 10 9  
Assets, Fair Value Disclosure 17 20  
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 20  
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 7 11  
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 7 11  
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 15 16  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (7) (9)  
Total liabilities (7) (9)  
Fair Value, Net Asset (Liability) 8 7  
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 15 16  
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 15 16  
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  
PECO Energy Co [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]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 43 51  
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 4  
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 23 0  
Assets, Fair Value Disclosure 30 14  
Total mark-to-market derivative liabilities 0 0  
Deferred Compensation Liability, Current and Noncurrent (4) (7)  
Total liabilities (4) (7)  
Fair Value, Net Asset (Liability) 26 7  
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 7 14  
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 7 14  
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 23 0  
Assets, Fair Value Disclosure 30 14  
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) 30 14  
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 7 14  
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 7 14  
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 (4) (7)  
Total liabilities (4) (7)  
Fair Value, Net Asset (Liability) (4) (7)  
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  
Baltimore Gas and Electric Company [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]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 165 100  
Pepco Holdings LLC [Member] | Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 3 3  
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 205 110  
Assets, Fair Value Disclosure 343 255  
Deferred Compensation Liability, Current and Noncurrent (14) (18)  
Total liabilities (14) (18)  
Fair Value, Net Asset (Liability) 329 237  
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 138 145  
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 59 59  
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 11 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 7 10  
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 61 62  
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 205 110  
Assets, Fair Value Disclosure 275 183  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 275 183  
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 70 73  
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 59 59  
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 11 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 29 37  
Deferred Compensation Liability, Current and Noncurrent (14) (18)  
Total liabilities (14) (18)  
Fair Value, Net Asset (Liability) 15 19  
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 29 37  
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 7 10  
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 22 27  
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 39 35  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 39 35  
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 39 35  
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 39 35  
Pepco Holdings LLC [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]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 45 34  
Potomac Electric Power Company [Member] | Restricted cash [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Cash and Cash Equivalents, Fair Value Disclosure 3 3  
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 51 31  
Assets, Fair Value Disclosure 170 151  
Deferred Compensation Liability, Current and Noncurrent (1) (2)  
Total liabilities (1) (2)  
Fair Value, Net Asset (Liability) 169 149  
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 119 120  
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 59 58  
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 62  
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 51 31  
Assets, Fair Value Disclosure 110 89  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 110 89  
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 59 58  
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 59 58  
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 22 27  
Deferred Compensation Liability, Current and Noncurrent (1) (2)  
Total liabilities (1) (2)  
Fair Value, Net Asset (Liability) 21 25  
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 22 27  
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] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 22 27  
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 38 35  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 38 35  
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 38 35  
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] | 6311 Life Insurance [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Investments, Fair Value Disclosure 38 35  
Potomac Electric Power Company [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]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 31 28  
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 121 43  
Assets, Fair Value Disclosure 121 43  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 121 43  
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] | 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 121 43  
Assets, Fair Value Disclosure 121 43  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 121 43  
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] | 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] | 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] | 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 Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Assets, Fair Value Disclosure 0 0  
Total liabilities 0 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 71 29  
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 1 0  
Assets, Fair Value Disclosure 1 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 1 0  
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] | 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 1 0  
Assets, Fair Value Disclosure 1 0  
Deferred Compensation Liability, Current and Noncurrent 0 0  
Total liabilities 0 0  
Fair Value, Net Asset (Liability) 1 0  
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] | 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] | 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] | 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 Measured at Net Asset Value Per Share [Member] | Fair Value, Recurring [Member]      
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]      
Assets, Fair Value Disclosure 0 0  
Total liabilities $ 0 $ 0