Fair Value of Financial Assets and Liabilities - Fair Value Measurement of Assets and Liabilities, Recurring (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Market-to-market derivative liabilities, current	$ 74	$ 8
Derivative Liability, Noncurrent	106	83
Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	334	345
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	334	345
Restricted cash [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	149	81
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	149	81
Other assets
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	174	117
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	174	117
Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	618	664
Assets, Fair Value Disclosure	861	891
Obligations, Fair Value Disclosure	75	75
Total liabilities	(254)	(166)
Fair Value, Net Asset (Liability)	607	725
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	618	664
Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	133	84
Fair Value, Recurring [Member] | Interest Rate Derivative Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	46	7
Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	24	4
Fair Value, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	22	3
Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	231	216
Fair Value, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	67	62
Fair Value, Recurring [Member] | Mutual Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	53	49
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	7
Fair Value, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	104	98
Fair Value, Recurring [Member] | Interest Rate Derivative Assets
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	12	11
Fair Value, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	11	6
Fair Value, Recurring [Member] | Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1	5
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	618	664
Assets, Fair Value Disclosure	738	775
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	738	775
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	618	664
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	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]
Trading Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	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]
Trading Liabilities, 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	120	111
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	67	62
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	53	49
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] | Interest Rate Derivative Assets
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] | 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 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	80	76
Obligations, Fair Value Disclosure	75	75
Total liabilities	(121)	(82)
Fair Value, Net Asset (Liability)	(41)	(6)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	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]
Trading Liabilities, Fair Value Disclosure	46	7
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	24	4
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]
Trading Liabilities, Fair Value Disclosure	22	3
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	68	65
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	7
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	61	58
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	12	11
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	11	6
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	1	5
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	43	40
Obligations, Fair Value Disclosure	0	0
Total liabilities	(133)	(84)
Fair Value, Net Asset (Liability)	(90)	(44)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	133	84
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]
Trading Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Derivatives Designated as Hedging Instruments Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
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]
Trading Liabilities, 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	43	40
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	43	40
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, 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
Commonwealth Edison Co
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Market-to-market derivative liabilities, current	27	5
Derivative Liability, Noncurrent	106	79
Commonwealth Edison Co | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	86	42
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	86	42
Commonwealth Edison Co | Restricted cash [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	147	77
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	147	77
Commonwealth Edison Co | Other assets
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	174	117
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	174	117
Commonwealth Edison Co | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	453	392
Derivative Asset	0
Assets, Fair Value Disclosure	453	392
Obligations, Fair Value Disclosure	8	8
Total liabilities	(141)	(92)
Fair Value, Net Asset (Liability)	312	300
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	453	392
Commonwealth Edison Co | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	133	84
Commonwealth Edison Co | 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 | 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 | 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 | 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	453	392
Assets, Fair Value Disclosure	453	392
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	453	392
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	453	392
Commonwealth Edison Co | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Commonwealth Edison Co | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	8	8
Total liabilities	(8)	(8)
Fair Value, Net Asset (Liability)	(8)	(8)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Commonwealth Edison Co | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Commonwealth Edison Co | 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 | 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 | 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 | Fair Value, Inputs, Level 3 [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Market-to-market derivative liabilities, current	27	5
Derivative Liability, Noncurrent	106	79
Commonwealth Edison Co | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	(133)	(84)
Fair Value, Net Asset (Liability)	(133)	(84)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Commonwealth Edison Co | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	133	84
Commonwealth Edison Co | 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 | 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 | 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 | 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 | 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	58
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	42	58
PECO Energy Co | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	9	10
Assets, Fair Value Disclosure	36	32
Obligations, Fair Value Disclosure	8	7
Total liabilities	(8)	(7)
Fair Value, Net Asset (Liability)	28	25
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	9	10
PECO Energy Co | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
PECO Energy Co | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	27	22
PECO Energy Co | Fair Value, Recurring [Member] | Mutual Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	9	7
PECO Energy Co | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	18	15
PECO Energy Co | 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	9	10
Assets, Fair Value Disclosure	18	17
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	18	17
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	9	10
PECO Energy Co | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
PECO Energy Co | 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	7
PECO Energy Co | 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	7
PECO Energy Co | 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 | 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	18	15
Obligations, Fair Value Disclosure	8	7
Total liabilities	(8)	(7)
Fair Value, Net Asset (Liability)	10	8
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
PECO Energy Co | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
PECO Energy Co | 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	18	15
PECO Energy Co | 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 | 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	18	15
PECO Energy Co | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
PECO Energy Co | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
PECO Energy Co | 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 | 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 | 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 | 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 | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	47	43
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	47	43
Baltimore Gas and Electric Company | Restricted cash [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	1
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	1
Baltimore Gas and Electric Company | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	23
Assets, Fair Value Disclosure	9	30
Obligations, Fair Value Disclosure	4	4
Total liabilities	(4)	(4)
Fair Value, Net Asset (Liability)	5	26
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	23
Baltimore Gas and Electric Company | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | 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	7
Baltimore Gas and Electric Company | Fair Value, Recurring [Member] | Mutual Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	9	7
Baltimore Gas and Electric Company | 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 | 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	23
Assets, Fair Value Disclosure	9	30
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	9	30
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	23
Baltimore Gas and Electric Company | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | 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	7
Baltimore Gas and Electric Company | 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	7
Baltimore Gas and Electric Company | 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 | 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
Obligations, Fair Value Disclosure	4	4
Total liabilities	(4)	(4)
Fair Value, Net Asset (Liability)	(4)	(4)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mark-to-Market Derivative Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Trading Liabilities, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company | 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 | 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 | 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 | 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 | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	96	165
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	96	165
Pepco Holdings LLC | Restricted cash [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	3
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	3
Pepco Holdings LLC | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	107	205
Assets, Fair Value Disclosure	249	343
Obligations, Fair Value Disclosure	13	14
Total liabilities	(13)	(14)
Fair Value, Net Asset (Liability)	236	329
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	107	205
Pepco Holdings LLC | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	142	138
Pepco Holdings LLC | Fair Value, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	64	59
Pepco Holdings LLC | Fair Value, Recurring [Member] | Mutual Fund [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	9	11
Pepco Holdings LLC | 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	7
Pepco Holdings LLC | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	62	61
Pepco Holdings LLC | 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	107	205
Assets, Fair Value Disclosure	180	275
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	180	275
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	107	205
Pepco Holdings LLC | 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	73	70
Pepco Holdings LLC | 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	64	59
Pepco Holdings LLC | 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	11
Pepco Holdings LLC | 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 | 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 | 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	29
Obligations, Fair Value Disclosure	13	14
Total liabilities	(13)	(14)
Fair Value, Net Asset (Liability)	15	15
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Pepco Holdings LLC | 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	29
Pepco Holdings LLC | 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 | 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 | 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	7
Pepco Holdings LLC | 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	21	22
Pepco Holdings LLC | 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	41	39
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	41	39
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Pepco Holdings LLC | 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	41	39
Pepco Holdings LLC | 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 | 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 | 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 | 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	41	39
Pepco Holdings LLC | 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 | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	48	45
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	48	45
Potomac Electric Power Company | Restricted cash [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	3
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	3
Potomac Electric Power Company | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	23	51
Assets, Fair Value Disclosure	148	170
Obligations, Fair Value Disclosure	1	1
Total liabilities	(1)	(1)
Fair Value, Net Asset (Liability)	147	169
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	23	51
Potomac Electric Power Company | Fair Value, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	125	119
Potomac Electric Power Company | Fair Value, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	63	59
Potomac Electric Power Company | Fair Value, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	62	60
Potomac Electric Power Company | 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	51
Assets, Fair Value Disclosure	86	110
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	86	110
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	23	51
Potomac Electric Power Company | 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	63	59
Potomac Electric Power Company | 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	63	59
Potomac Electric Power Company | 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 | 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	21	22
Obligations, Fair Value Disclosure	1	1
Total liabilities	(1)	(1)
Fair Value, Net Asset (Liability)	20	21
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Potomac Electric Power Company | 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	21	22
Potomac Electric Power Company | 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 | 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	21	22
Potomac Electric Power Company | 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	41	38
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	41	38
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Potomac Electric Power Company | 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	41	38
Potomac Electric Power Company | 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 | 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	41	38
Potomac Electric Power Company | 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 | 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	31
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	15	31
Delmarva Power & Light Company | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	121
Assets, Fair Value Disclosure	1	121
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	1	121
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	121
Delmarva Power & Light Company | 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 | 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 | 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 | 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	121
Assets, Fair Value Disclosure	1	121
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	1	121
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	1	121
Delmarva Power & Light Company | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Delmarva Power & Light Company | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Delmarva Power & Light Company | 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 | 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 | 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 | 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 | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	21	71
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	21	71
Atlantic City Electric Company | Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	1
Assets, Fair Value Disclosure	0	1
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	1
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	1
Atlantic City Electric Company | 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 | 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 | 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 | 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	1
Assets, Fair Value Disclosure	0	1
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	1
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	1
Atlantic City Electric Company | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Atlantic City Electric Company | 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 | 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 | 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 | 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
Obligations, Fair Value Disclosure	0	0
Total liabilities	0	0
Fair Value, Net Asset (Liability)	0	0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Atlantic City Electric Company | 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 | 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 | 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 | 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