Derivative Financial Instruments - Summary of Counterparty Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 675	$ 577
External Counterparties \| Commodity Contract [Member] \| Collateral [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	312	223
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Commonwealth Edison Co
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	231	192
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| PECO Energy Co
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	18	6
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Baltimore Gas and Electric Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	4	4
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Pepco Holdings LLC
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	59	21
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Potomac Electric Power Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	21	13
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Delmarva Power and Light Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	2	3
External Counterparties \| Commodity Contract [Member] \| Collateral [Member] \| Atlantic City Electric Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 36	$ 5