Derivative Financial Instruments - Summary of Counterparty Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 933	$ 1,155
External Counterparties | Commodity Contract [Member] | Collateral [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	112	297
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Commonwealth Edison Co
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	105	77
External Counterparties | Commodity Contract [Member] | Collateral [Member] | PECO Energy Co
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	0	0
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Baltimore Gas and Electric Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	1	23
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Pepco Holdings LLC
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	6	197
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Potomac Electric Power Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	0	26
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Delmarva Power and Light Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	1	121
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Atlantic City Electric Company
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 5	$ 50