Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 413	$ 428
Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	293	303
PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	27	27
Baltimore Gas and Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	14	14
Pepco Holdings LLC
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	76	81
Potomac Electric Power Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	74	79
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	328	338
Accrual For MGP Investigation And Remediation [Member] | Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	292	302
Accrual For MGP Investigation And Remediation [Member] | PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	25	25
Accrual For MGP Investigation And Remediation [Member] | Baltimore Gas and Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	11	11
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