Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)	$ 0	$ 18
Derivative Liability, Noncurrent	67	201
Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	664	524
Derivative Asset	24
Assets, Fair Value Disclosure	903	752
Deferred Compensation Liability, Current and Noncurrent	(68)	(131)
Total Liabilities	(135)	(350)
Fair Value, Net Asset (Liability)	768	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	(67)	(219)
Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	384	464
Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	225	49
Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	83	44
Fair Value, Recurring [Member] \| Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	215	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 Funds [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	8	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	96	98
Fair Value, Recurring [Member] \| Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	24	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	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] \| 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 Funds [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] \| 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 equivalents	0	0
Assets, Fair Value Disclosure	65	71
Deferred Compensation Liability, Current and Noncurrent	(68)	(131)
Total Liabilities	(68)	(131)
Fair Value, Net Asset (Liability)	(3)	(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	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	8	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	57	61
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	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0
Assets, Fair Value Disclosure	63	37
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(67)	(219)
Fair Value, Net Asset (Liability)	(4)	(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	(67)	(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	39	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 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	39	37
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	24	0
Commonwealth Edison Co [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Mark-to-market derivative liabilities (current liabilities)	0	18
Derivative Liability, Noncurrent	67	201
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	354	237
Derivative Asset	24	0
Assets, Fair Value Disclosure	378	237
Total mark-to-market derivative liabilities	(67)	(219)
Deferred Compensation Liability, Current and Noncurrent	(7)	(10)
Total Liabilities	(74)	(229)
Fair Value, Net Asset (Liability)	304	8
Mark-to-market derivative liabilities (current liabilities)	0	18
Derivative Liability, Noncurrent	(67)	201
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	39	105
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	95	42
Commonwealth Edison Co [Member] \| Fair Value, Recurring [Member] \| Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	83	43
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 Funds [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 equivalents	354	237
Derivative Asset	0
Assets, Fair Value Disclosure	354	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)	354	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 Funds [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 equivalents	0	0
Derivative Asset	0
Assets, Fair Value Disclosure	0	0
Total mark-to-market derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	(7)	(10)
Total Liabilities	(7)	(10)
Fair Value, Net Asset (Liability)	(7)	(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 Funds [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] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	0	0
Derivative Asset	24
Assets, Fair Value Disclosure	24	0
Total mark-to-market derivative liabilities	(67)	(219)
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	(67)	(219)
Fair Value, Net Asset (Liability)	(43)	(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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Commonwealth Edison Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
PECO Energy Co [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	10	9
Derivative Asset	0
Assets, Fair Value Disclosure	33	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)	26	27
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	93	35
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	23	27
PECO Energy Co [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	8	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 equivalents	10	9
Derivative Asset	0
Assets, Fair Value Disclosure	18	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)	18	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	8	11
PECO Energy Co [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	8	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 equivalents	0	0
Derivative Asset	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 Funds [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 equivalents	0	0
Derivative Asset	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
PECO Energy Co [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1	0
Derivative Asset	0
Assets, Fair Value Disclosure	8	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)	4	7
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	20	51
Baltimore Gas and Electric Company [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	129	4
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 Funds [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 equivalents	1	0
Derivative Asset	0
Assets, Fair Value Disclosure	8	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)	8	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 Funds [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 equivalents	0	0
Derivative Asset	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 Funds [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 equivalents	0	0
Derivative Asset	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Baltimore Gas and Electric Company [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0	0
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	266	110
Assets, Fair Value Disclosure	403	255
Deferred Compensation Liability, Current and Noncurrent	(14)	(18)
Total Liabilities	(14)	(18)
Fair Value, Net Asset (Liability)	389	237
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	186	100
Pepco Holdings LLC [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1	3
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	137	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	10	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	8	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	60	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 equivalents	266	110
Assets, Fair Value Disclosure	335	183
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	335	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	69	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 Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	10	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 equivalents	0	0
Assets, Fair Value Disclosure	30	37
Deferred Compensation Liability, Current and Noncurrent	(14)	(18)
Total Liabilities	(14)	(18)
Fair Value, Net Asset (Liability)	16	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	30	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 Funds [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	8	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 equivalents	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
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	38	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 Funds [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	38	35
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	76	31
Assets, Fair Value Disclosure	195	151
Deferred Compensation Liability, Current and Noncurrent	(1)	(2)
Total Liabilities	(1)	(2)
Fair Value, Net Asset (Liability)	194	149
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	21	34
Potomac Electric Power Company [Member] \| Fair Value, Recurring [Member] \| Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1	3
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 equivalents	76	31
Assets, Fair Value Disclosure	135	89
Deferred Compensation Liability, Current and Noncurrent	0	0
Total Liabilities	0	0
Fair Value, Net Asset (Liability)	135	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 equivalents	0	0

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($)
$ in Millions