Leases - Lessor - Components of Operating Lease Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	$ 5	$ 4	$ 5
Variable lease income	1	1	1
Commonwealth Edison Co
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	0	0	0
Variable lease income	0	0	0
PECO Energy Co
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	0	0	0
Variable lease income	0	0	0
Baltimore Gas and Electric Company
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	0	0	0
Variable lease income	0	0	0
Pepco Holdings LLC
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	4	4	4
Variable lease income	1	1	1
Potomac Electric Power Company
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	0	0	0
Variable lease income	0	0	0
Delmarva Power & Light Company
Schedule of Operating Lease, Lease Income [Line Items]
Operating lease income	3	3	3
Variable lease income	$ 1	$ 1	$ 1