Regulatory Matters - Capitalized Ratemaking Amounts Not Recognized (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 57	$ 43
Commonwealth Edison Co [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	8	1
PECO Energy Co [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	0	0
Baltimore Gas and Electric Company [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	28	37
Pepco Holdings LLC [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	21	5
Potomac Electric Power Company [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	18	3
Delmarva Power & Light Company [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	2	2
Atlantic City Electric Company [Member]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 1	$ 0