Income Taxes - Allocation of Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Commonwealth Edison Co
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	$ 13	$ 1	$ 1
PECO Energy Co
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	19	47	19
Baltimore Gas and Electric Company
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	0	0	0
Pepco Holdings LLC
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	10	28	17
Potomac Electric Power Company
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	4	23	16
Delmarva Power and Light Company [Member]
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	0	3	0
Atlantic City Electric Company
Income Taxes [Line Items]
Allocation Of Federal Tax Benefit Under Tax Sharing Agreement	$ 2	$ 2	$ 0