Income Taxes - Components of Income Tax Expense (Benefit) from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Current federal tax expense (benefit)	$ 51	$ (24)	$ (152)
Deferred federal income tax expense (benefit)	193	106	89
Investment tax credit amortization	(2)	(3)	(2)
Current state and local tax expense (benefit)	4	(13)	(46)
Deferred state and local income tax expense (benefit)	128	283	149
Income taxes	374	349	38
Commonwealth Edison Co
Income Taxes [Line Items]
Current federal tax expense (benefit)	130	29	(30)
Deferred federal income tax expense (benefit)	45	117	113
Investment tax credit amortization	(1)	(1)	(1)
Current state and local tax expense (benefit)	(13)	(6)	(41)
Deferred state and local income tax expense (benefit)	153	125	131
Income taxes	314	264	172
PECO Energy Co
Income Taxes [Line Items]
Current federal tax expense (benefit)	63	13	1
Deferred federal income tax expense (benefit)	(36)	18	20
Investment tax credit amortization	0	0	0
Current state and local tax expense (benefit)	0	(4)	0
Deferred state and local income tax expense (benefit)	(7)	52	(9)
Income taxes	20	79	12
Baltimore Gas and Electric Company
Income Taxes [Line Items]
Current federal tax expense (benefit)	67	(1)	(18)
Deferred federal income tax expense (benefit)	16	(3)	34
Investment tax credit amortization	0	0	0
Current state and local tax expense (benefit)	0	0	0
Deferred state and local income tax expense (benefit)	50	12	(51)
Income taxes	133	8	(35)
Pepco Holdings LLC
Income Taxes [Line Items]
Current federal tax expense (benefit)	71	16	18
Deferred federal income tax expense (benefit)	(8)	(23)	(52)
Investment tax credit amortization	(1)	(1)	(1)
Current state and local tax expense (benefit)	15	2	0
Deferred state and local income tax expense (benefit)	39	15	77
Income taxes	116	9	42
Potomac Electric Power Company
Income Taxes [Line Items]
Current federal tax expense (benefit)	54	9	22
Deferred federal income tax expense (benefit)	(28)	(2)	(17)
Investment tax credit amortization	0	0	0
Current state and local tax expense (benefit)	12	0	1
Deferred state and local income tax expense (benefit)	13	(16)	9
Income taxes	51	(9)	15
Delmarva Power & Light Company
Income Taxes [Line Items]
Current federal tax expense (benefit)	25	(2)	2
Deferred federal income tax expense (benefit)	(6)	2	(14)
Investment tax credit amortization	0	0	0
Current state and local tax expense (benefit)	6	0	1
Deferred state and local income tax expense (benefit)	10	14	53
Income taxes	35	14	42
Atlantic City Electric Company
Income Taxes [Line Items]
Current federal tax expense (benefit)	9	6	1
Deferred federal income tax expense (benefit)	13	(15)	(26)
Investment tax credit amortization	0	0	0
Current state and local tax expense (benefit)	0	0	0
Deferred state and local income tax expense (benefit)	14	12	12
Income taxes	$ 36	$ 3	$ (13)