Leases - Lessee - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	$ 65	$ 66	$ 93
Commonwealth Edison Co
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	2	3	3
PECO Energy Co
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	0	0	0
Baltimore Gas and Electric Company
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	15	16	46
Pepco Holdings LLC
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	37	37	39
Finance lease, principal payments	15	13	10
Potomac Electric Power Company
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	7	8	8
Finance lease, principal payments	5	5	3
Delmarva Power & Light Company
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	9	9	9
Finance lease, principal payments	6	5	4
Atlantic City Electric Company
Supplemental Cash Flow Information [Line Items]
Operating cash flows from operating leases	3	4	4
Finance lease, principal payments	$ 4	$ 3	$ 3