Intangible Assets - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross	$ 1,095	$ 1,091
Accumulated Amortization	(916)	(919)
Net	179	172
Unamortized Energy Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	448	448
Accumulated Amortization	(393)	(454)
Net	55	(6)
Exelon Generation Co L L C [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	330	326
Accumulated Amortization	(243)	(215)
Net	87	111
Exelon Generation Co L L C [Member] | Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	222	222
Accumulated Amortization	(218)	(197)
Net	4	25
Business Services Company [Member] | Licensing Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	95	95
Accumulated Amortization	(62)	(53)
Net	33	42
Pepco Holdings LLC [Member] | Unamortized Energy Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	(1,515)	(1,515)
Accumulated Amortization	1,280	1,188
Net	$ (235)	$ (327)