Supplemental Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 616	$ 445	$ 300	$ 407
Restricted cash	552	482	435	566
Restricted cash included in other long-term assets	65	174	212	117
Total cash, restricted cash, and cash equivalents	1,233	1,101	947	1,090
Accrued Expenses [Abstract]
Compensation-related accruals	546	661
Taxes accrued	203	221
Interest accrued	431	414
Other	569	557
Commonwealth Edison Co
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	109	110	79	67
Restricted cash	481	402	360	327
Restricted cash included in other long-term assets	65	174	212	117
Total cash, restricted cash, and cash equivalents	655	686	651	511
Accrued Expenses [Abstract]
Compensation-related accruals	165	206
Taxes accrued	89	204
Interest accrued	92	148
PECO Energy Co
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	28	42	43	59
Restricted cash	9	9	9	9
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	37	51	52	68
Accrued Expenses [Abstract]
Compensation-related accruals	68	87
Taxes accrued	19	96
Interest accrued	55	49
Baltimore Gas and Electric Company
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	330	47	15	43
Restricted cash	0	1	1	24
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	330	48	16	67
Accrued Expenses [Abstract]
Compensation-related accruals	70	81
Taxes accrued	28	75
Interest accrued	74	44
Other	48	9
Pepco Holdings LLC
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	100	180	121	198
Restricted cash	22	24	25	175
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	122	204	146	373
Accrued Expenses [Abstract]
Compensation-related accruals	100	107
Taxes accrued	101	137
Interest accrued	85	72
Potomac Electric Power Company
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	20	48	31	45
Restricted cash	20	24	25	54
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	40	72	56	99
Accrued Expenses [Abstract]
Compensation-related accruals	28	27
Taxes accrued	89	116
Interest accrued	38	38
Delmarva Power and Light Company
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	8	16	5	31
Restricted cash	2	0	1	121
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	10	16	6	152
Accrued Expenses [Abstract]
Compensation-related accruals	19	17
Taxes accrued	15	30
Interest accrued	27	13
Atlantic City Electric Company
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	17	21	14	72
Restricted cash	0	0	0	0
Restricted cash included in other long-term assets	0	0	0	0
Total cash, restricted cash, and cash equivalents	17	21	$ 14	$ 72
Accrued Expenses [Abstract]
Compensation-related accruals	12	12
Taxes accrued	5	10
Interest accrued	$ 18	$ 15