Supplemental Financial Information - Taxes Other Than Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Supplemental Statement of Operations Information [Line Items]
Utility taxes	$ 229	$ 220
Property	105	99
Payroll	34	32
Commonwealth Edison Co
Supplemental Statement of Operations Information [Line Items]
Utility taxes	75	74
Property	9	10
Payroll	9	7
PECO Energy Co
Supplemental Statement of Operations Information [Line Items]
Utility taxes	41	40
Property	4	4
Payroll	5	5
Baltimore Gas and Electric Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	31	29
Property	53	50
Payroll	5	5
Pepco Holdings LLC
Supplemental Statement of Operations Information [Line Items]
Utility taxes	82	77
Property	38	35
Payroll	7	7
Potomac Electric Power Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	74	68
Property	26	24
Payroll	2	2
Delmarva Power and Light Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	8	8
Property	11	11
Payroll	1	1
Atlantic City Electric Company
Supplemental Statement of Operations Information [Line Items]
Utility taxes	0	1
Property	1	0
Payroll	$ 1	$ 1