Derivative Financial Instruments - Narrative (Details) MWh in Millions, $ in Millions	1 Months Ended
	Jun. 30, 2012 MWh	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Derivative [Line Items]
Other		$ 964	$ 766
Commonwealth Edison Co [Member]
Derivative [Line Items]
Long-term Purchase Commitment, Minimum Energy Volume Required | MWh	1.3
Other		161	133
PECO Energy Co [Member]
Derivative [Line Items]
Other		41	35
Incremental Collateral For Loss Of Investment Grade Credit Rating		39
Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Other		61	48
Incremental Collateral For Loss Of Investment Grade Credit Rating		62
Delmarva Power and Light Company [Member]
Derivative [Line Items]
Other		88	59
Incremental Collateral For Loss Of Investment Grade Credit Rating		16
Atlantic City Electric Company [Member]
Derivative [Line Items]
Other		18	12
Pepco Holdings LLC [Member]
Derivative [Line Items]
Other		215	171
Commodity Contract [Member] | External Counterparties | Collateral [Member]
Derivative [Line Items]
Other		192
Commodity Contract [Member] | Commonwealth Edison Co [Member] | External Counterparties | Collateral [Member]
Derivative [Line Items]
Other		72	41
Commodity Contract [Member] | Delmarva Power and Light Company [Member] | External Counterparties | Collateral [Member]
Derivative [Line Items]
Other		73	$ 43
Commodity Contract [Member] | Pepco Holdings LLC [Member] | External Counterparties | Collateral [Member]
Derivative [Line Items]
Other		$ 86