Commitments and Contingencies - Schedule of Spent Nuclear Fuel Obligation (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Spent Nuclear Fuel Obligation [Line Items]
Spent Nuclear Fuel Obligation, Noncurrent	$ 1,210	$ 1,208
Spent Nuclear Fuel One Time Fee			$ 34
Exelon Generation Co L L C [Member]
Spent Nuclear Fuel Obligation [Line Items]
Spent Nuclear Fuel Obligation, Noncurrent	1,210	1,208
Spent Nuclear Fuel One Time Fee			$ 277
Exelon Generation Co L L C [Member] | Nuclear Plant [Member]
Spent Nuclear Fuel Obligation [Line Items]
Spent Nuclear Fuel Obligation, Noncurrent	1,083	1,082
Exelon Generation Co L L C [Member] | Fitzpatrick [Member]
Spent Nuclear Fuel Obligation [Line Items]
Spent Nuclear Fuel Obligation, Noncurrent	$ 127	$ 126