Regulatory Matters - Schedule of Pending Rate Cases (Details) - USD ($) $ in Millions								12 Months Ended
	Mar. 31, 2021	Mar. 30, 2021	Feb. 26, 2021	Feb. 02, 2021	Sep. 30, 2020	Jun. 01, 2020	Apr. 16, 2020	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)							$ 51
Requested Return on Equity, Percentage							7.36%
Public Utilities, Requested Rate Increase (Decrease), Initial Revenue Requirement, Amount							$ 40
Public Utilities Requested Rate Increase (Decrease), Prior Year Annual Reconciliation							$ 11
Requested Return on Distribution Rate Base, Percentage							5.72%
Basis points for ComEd's Revenue Requirement							580
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case 2020 Reconciliation
Regulatory Matters Pending Rate Cases [Line Items]
Requested Return on Equity, Percentage							7.29%
Requested Return on Distribution Rate Base, Percentage							5.69%
Basis points for ComEd's Revenue Requirement							580
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case 2020 Reconciliation | Performance Metrics Penalty
Regulatory Matters Pending Rate Cases [Line Items]
Basis points for ComEd's Revenue Requirement							7
PECO Energy Co [Member] | Pennsylvania 2021 Electric Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)		$ 246
Requested Return on Equity, Percentage		10.95%
PECO Energy Co [Member] | Pennsylvania 2020 Natural Gas Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)					$ 69
Requested Return on Equity, Percentage					10.95%
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended						$ 136			$ 63	$ 73
Requested Return on Equity, Percentage						9.70%
Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended	$ 104							$ 52	$ 52
Requested Return on Equity, Percentage	10.20%
Delmarva Power and Light Company [Member] | Delaware 2020 Electric Distribution Base Rate Case [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended				$ 23
Requested Return on Equity, Percentage				10.30%
Atlantic City Electric Company [Member] | New Jersey 2020 Electric Distribution Base Rate Case
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended			$ 67
Requested Return on Equity, Percentage			10.30%