Supplemental Financial Information - Taxes Other Than Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Supplemental Statement of Operations Information [Line Items]
Utility taxes	$ 248	$ 244	$ 695	$ 665
Property	111	104	323	300
Payroll	33	31	100	93
Commonwealth Edison Co
Supplemental Statement of Operations Information [Line Items]
Utility taxes	80	82	229	228
Property	7	9	25	27
Payroll	9	8	27	22
PECO Energy Co
Supplemental Statement of Operations Information [Line Items]
Utility taxes	51	50	134	128
Property	5	4	14	12
Payroll	4	4	13	13
Baltimore Gas and Electric Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	25	23	78	73
Property	57	53	164	153
Payroll	5	5	14	14
Pepco Holdings LLC
Supplemental Statement of Operations Information [Line Items]
Utility taxes	92	89	254	236
Property	41	38	119	108
Payroll	7	7	22	22
Potomac Electric Power Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	84	82	230	213
Property	28	25	81	73
Payroll	2	2	6	5
Delmarva Power and Light Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	7	6	21	20
Property	12	12	35	34
Payroll	1	1	3	3
Atlantic City Electric Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	1	1	3	3
Property	1	1	2	1
Payroll	$ 0	$ 1	$ 2	$ 3