Supplemental Financial Information - Taxes Other Than Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Supplemental Statement of Operations Information [Line Items]
Utility taxes	$ 203	$ 184	$ 424	$ 377
Property	94	86	188	173
Payroll	28	32	64	64
Commonwealth Edison Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	71	61	149	121
Property	10	8	20	16
Payroll	7	6	13	13
PECO Energy Co [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	39	32	77	66
Property	4	4	9	9
Payroll	5	4	8	8
Baltimore Gas and Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	20	20	47	45
Property	46	43	92	85
Payroll	4	5	9	9
Pepco Holdings LLC [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	73	71	151	145
Property	33	31	67	63
Payroll	7	7	14	14
Potomac Electric Power Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	67	65	137	132
Property	23	20	46	42
Payroll	1	1	3	3
Delmarva Power and Light Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	5	5	12	11
Property	10	10	20	19
Payroll	1	1	2	3
Atlantic City Electric Company [Member]
Supplemental Statement of Operations Information [Line Items]
Utility taxes	1	0	2	1
Property	0	1	1	1
Payroll	$ 1	$ 1	$ 2	$ 2