Regulatory Matters - Capitalized Ratemaking Amounts Not Recognized (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 110	$ 57
Commonwealth Edison Co
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	32	8
PECO Energy Co
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	0	0
Baltimore Gas and Electric Company
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	33	28
Pepco Holdings LLC
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	45	21
Potomac Electric Power Company
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	34	18
Delmarva Power & Light Company
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	1	2
Atlantic City Electric Company
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 10	$ 1