Subsequent Events Subsequent Events - Narrative (Details) - Exelon Generation Co L L C [Member] - Subsequent Event [Member] $ in Millions	Dec. 31, 2018 USD ($)
Subsequent Event [Line Items]
Net long-lived assets	$ 750
Non-recourse debt	510
Antelope Valley [Member]
Subsequent Event [Line Items]
Net long-lived assets	1,990
Antelope Valley [Member] | ExGenRenewablesIVNov2024 [Member]
Subsequent Event [Line Items]
Non-recourse debt	$ 830