Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 434	$ 409
Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	312	325
PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	28	25
Baltimore Gas and Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	9	9
Pepco Holdings LLC
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	82	46
Potomac Electric Power Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	80	44
Delmarva Power and Light Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	1	1
Atlantic City Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	1	1
Accrual For MGP Investigation And Remediation [Member]
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	345	355
Accrual For MGP Investigation And Remediation [Member] | Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	311	324
Accrual For MGP Investigation And Remediation [Member] | PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	26	23
Accrual For MGP Investigation And Remediation [Member] | Baltimore Gas and Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	8	8
Accrual For MGP Investigation And Remediation [Member] | Pepco Holdings LLC
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] | Potomac Electric Power Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] | Delmarva Power and Light Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Accrual For MGP Investigation And Remediation [Member] | Atlantic City Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 0	$ 0