Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 410	$ 428
Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	290	303
PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	31	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	75	81
Potomac Electric Power Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	73	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
Environmental Remediation
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	328	338
Environmental Remediation | Commonwealth Edison Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	289	302
Environmental Remediation | PECO Energy Co
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	28	25
Environmental Remediation | Baltimore Gas and Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	11	11
Environmental Remediation | Pepco Holdings LLC
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Environmental Remediation | Potomac Electric Power Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Environmental Remediation | Delmarva Power and Light Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	0	0
Environmental Remediation | Atlantic City Electric Company
Site Contingency [Line Items]
Total environmental investigation and remediation reserve	$ 0	$ 0