Regulatory Matters - Capitalized Ratemaking Amount Not Recognized (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 67	$ 98
Commonwealth Edison Co
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	10	12
PECO Energy Co
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	0	0
Baltimore Gas and Electric Company
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	31	47
Pepco Holdings LLC
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	26	39
Potomac Electric Power Company
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	11	22
Delmarva Power and Light Company
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	0	1
Atlantic City Electric Company
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Amount of Allowance for Earnings on Equity Capitalized for Rate Making Purposes	$ 15	$ 16