Regulatory Matters - Schedule of Completed Rate Cases (Details) - USD ($) $ in Millions											12 Months Ended
	Jan. 06, 2021	Dec. 16, 2020	Dec. 09, 2020	Oct. 09, 2020	Sep. 11, 2020	Jul. 14, 2020	Apr. 23, 2020	Apr. 16, 2020	Dec. 04, 2019	Apr. 08, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commonwealth Edison Co [Member] | Illinois 2019 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount										$ (6)
Public Utilities, Approved Rate Increase (Decrease), Amount									$ (17)							$ (68)
Public Utilities, Approved Return on Equity, Percentage									8.91%
Basis points for ComEd's Revenue Requirement															580
Public Utilities, Approved Equity Capital Structure, Percentage															6.51%
Public Utilities, Interim Rate Increase (Decrease), Amount															$ 51
Commonwealth Edison Co [Member] | Illinois 2020 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount								$ (11)
Public Utilities, Approved Rate Increase (Decrease), Amount			$ (14)												$ (64)
Public Utilities, Approved Return on Equity, Percentage			8.38%
Basis points for ComEd's Revenue Requirement														580
Public Utilities, Approved Equity Capital Structure, Percentage														6.28%
Public Utilities, Interim Rate Increase (Decrease), Amount														$ 50
Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member]
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount					$ 137
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 81
Public Utilities, Approved Return on Equity, Percentage		9.50%
Public Utilities, Interim Rate Increase (Decrease), Amount											$ 42	$ 39	$ 59
Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member]
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount					$ 91
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 21
Public Utilities, Approved Return on Equity, Percentage		9.65%
Public Utilities, Interim Rate Increase (Decrease), Amount											$ 10	$ 11	$ 53
Delmarva Power & Light Company [Member] | Maryland 2019 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount							$ 17
Public Utilities, Approved Rate Increase (Decrease), Amount						$ 12
Public Utilities, Approved Return on Equity, Percentage						9.60%
Delmarva Power & Light Company [Member] | Delaware 2020 Gas Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount				$ 7
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 2
Public Utilities, Approved Return on Equity, Percentage	9.60%