Jointly Owned Electric Utility Plant - Ownership Interests in Jointly Owned Electric Plants and Transmission Facilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) V mi	Dec. 31, 2020 USD ($)
Delaware And New Jersey [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Miles of transmission voltage lines | mi	151.3
Transmission line capacity | V	500
Delaware River Crossing [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Miles of transmission voltage lines | mi	2.5
Transmission line capacity | V	500
New Freedom Switching [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Transmission line capacity | V	500
Nuclear Plant [Member] | Quad Cities [Member] | Exelon Generation Co L L C [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	75.00%
Plant	$ 1,211	$ 1,188
Accumulated depreciation	715	670
Construction work in progress	$ 11	13
Nuclear Plant [Member] | Peach Bottom [Member] | Exelon Generation Co L L C [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	50.00%
Plant	$ 1,515	1,506
Accumulated depreciation	628	601
Construction work in progress	$ 12	13
Nuclear Plant [Member] | Salem [Member] | Exelon Generation Co L L C [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	42.59%
Plant	$ 756	717
Accumulated depreciation	299	265
Construction work in progress	$ 20	39
Nuclear Plant [Member] | Nine Mile Point [Member] | Exelon Generation Co L L C [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	82.00%
Plant	$ 1,002	990
Accumulated depreciation	222	187
Construction work in progress	41	25
Electric Transmission [Member] | Delaware And New Jersey [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Plant	103	103
Accumulated depreciation	55	54
Construction work in progress	$ 0	$ 0
PECO Energy Co [Member] | Delaware And New Jersey [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	42.55%
PECO Energy Co [Member] | Delaware River Crossing [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	42.55%
Delmarva Power & Light Company [Member] | Delaware And New Jersey [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	1.00%
Delmarva Power & Light Company [Member] | Delaware River Crossing [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	7.45%
Atlantic City Electric Company [Member] | Delaware And New Jersey [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	13.90%
Atlantic City Electric Company [Member] | Delaware River Crossing [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	7.45%
Atlantic City Electric Company [Member] | New Freedom Switching [Member]
Schedule Of Jointly Owned Utility Plant Net Ownership [Abstract]
Ownership interest	21.78%