Derivative Financial Instruments - Summary of Counterparty Collateral (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 976	$ 1,155
Commonwealth Edison Co [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	189	191
Baltimore Gas and Electric Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	34	55
Pepco Holdings LLC [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	149	330
Potomac Electric Power Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	75	93
Delmarva Power and Light Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	17	136
Atlantic City Electric Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	12	58
External Counterparties | Commodity Contract [Member] | Collateral [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	81	297
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Commonwealth Edison Co [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	73	77
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Baltimore Gas and Electric Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	1	23
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Pepco Holdings LLC [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	8	197
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Potomac Electric Power Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	1	26
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Delmarva Power and Light Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	1	121
External Counterparties | Commodity Contract [Member] | Collateral [Member] | Atlantic City Electric Company [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Other	$ 6	$ 50