Regulatory Matters - Schedule of Completed Rate Cases (Details) - USD ($) $ in Millions	Mar. 02, 2022	Feb. 23, 2022	Dec. 23, 2021	Dec. 22, 2021	Dec. 01, 2021	Nov. 18, 2021	Jul. 14, 2021	Jun. 28, 2021	Jun. 08, 2021	Apr. 16, 2021	Mar. 31, 2021	Mar. 30, 2021	Feb. 26, 2021	Dec. 16, 2020	Sep. 11, 2020	Jun. 01, 2020
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)										$ 51
Approved Revenue Requirement Increase (Decrease)					$ 46
Approved Return on Equity, Percentage					7.36%
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)					$ 37
Approved Return on Equity, Percentage					7.36%
Public Utilities, Approved Equity Capital Structure, Percentage					5.72%
Basis points for ComEd's Revenue Requirement					580
Commonwealth Edison Co [Member] | Illinois 2021 Electric Distribution Base Rate Case 2020 Reconciliation | 2020
Regulatory Matters Completed Rate Cases [Line Items]
Approved Return on Equity, Percentage					7.29%
Public Utilities Requested Rate Increase (Decrease), Prior Year Annual Reconciliation					$ 9
Public Utilities, Approved Equity Capital Structure, 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 | 2020
Regulatory Matters Completed 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 Completed Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)												$ 246
Approved Revenue Requirement Increase (Decrease)						$ 132
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															$ 203
Approved Revenue Requirement Increase (Decrease)														$ 140
Approved Return on Equity, Percentage														9.50%
Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2021
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														$ 59
Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														39
Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2023
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														42
Baltimore Gas and Electric Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | Offsets | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage				25.00%
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															$ 108
Approved Revenue Requirement Increase (Decrease)														$ 74
Approved Return on Equity, Percentage														9.65%
Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2021
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														$ 53
Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														11
Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | 2023
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)														$ 10
Baltimore Gas and Electric Company [Member] | Maryland 2020 Gas Distribution Base Rate Case [Member] | Offsets | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage				50.00%
Potomac Electric Power 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											$ 104
Approved Revenue Requirement Increase (Decrease)								$ 52
Approved Return on Equity, Percentage								9.55%
Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)								$ 21
Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2023
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)								16
Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | 2024
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)								$ 15
Potomac Electric Power Company [Member] | Maryland 2020 Electric Distribution Base Rate Case [Member] | Offsets | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage		25.00%
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member]
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount																$ 136
Approved Revenue Requirement Increase (Decrease)									$ 109
Approved Return on Equity, Percentage									9.275%
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2021
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)									$ 42
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)									67
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | Offsets | 2021
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)									(22)
Potomac Electric Power Company [Member] | District of Columbia 2019 Electric Distribution Base Rate Case [Member] | Offsets | 2022
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)									$ (40)
Delmarva Power and Light Company [Member] | Maryland 2021 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ 27
Approved Revenue Requirement Increase (Decrease)	$ 13
Approved Return on Equity, Percentage	9.60%
Atlantic City Electric Company [Member] | New Jersey 2020 Electric Distribution Base Rate Case
Regulatory Matters Completed Rate Cases [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount													$ 67
Approved Revenue Requirement Increase (Decrease)							$ 41
Approved Return on Equity, Percentage							9.60%
Atlantic City Electric Company [Member] | New Jersey 2020 Electric Distribution Base Rate Case | Tax Benefits
Regulatory Matters Completed Rate Cases [Line Items]
Approved Revenue Requirement Increase (Decrease)							$ 11