Supplemental Financial Information - Taxes Other Than Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Supplemental Statement of Operations Information [Line Items]
Utility taxes	$ 244	$ 215	$ 667	$ 592
Property	99	98	287	271
Payroll	28	33	92	97
Commonwealth Edison Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	84	67	233	188
Property	10	13	30	30
Payroll	7	7	21	20
PECO Energy Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	51	41	126	107
Property	4	5	12	13
Payroll	5	4	14	12
Baltimore Gas and Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	22	21	70	66
Property	50	46	142	131
Payroll	4	5	13	14
Pepco Holdings LLC [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	87	86	238	231
Property	35	34	103	97
Payroll	7	7	21	21
Potomac Electric Power Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	79	80	216	212
Property	23	23	70	65
Payroll	2	2	5	5
Delmarva Power and Light Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	7	6	19	17
Property	11	10	31	30
Payroll	1	1	4	4
Atlantic City Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	1	0	3	2
Property	1	1	2	2
Payroll	$ 0	$ 1	$ 2	$ 2