Revenue from Contracts with Customers - Change in Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Contract Liabilities [Roll Forward]
Contract with Customer, Liability, Current	$ 105	$ 107	$ 113	$ 116	$ 109	$ 118
Revenues recognized, contract liabilities	(2)	(2)	(3)	(2)
Pepco Holdings LLC [Member]
Contract Liabilities [Roll Forward]
Contract with Customer, Liability, Current	105	107	113	116	109	118
Revenues recognized, contract liabilities	(2)	(2)	(3)	(2)
Potomac Electric Power Company [Member]
Contract Liabilities [Roll Forward]
Contract with Customer, Liability, Current	84	85	91	92	87	94
Revenues recognized, contract liabilities	(1)	(2)	(1)	(2)
Delmarva Power and Light Company [Member]
Contract Liabilities [Roll Forward]
Contract with Customer, Liability, Current	11	11	11	12	11	12
Revenues recognized, contract liabilities	0	0	(1)	0
Atlantic City Electric Company [Member]
Contract Liabilities [Roll Forward]
Contract with Customer, Liability, Current	10	11	11	12	$ 11	$ 12
Revenues recognized, contract liabilities	$ (1)	$ 0	$ (1)	$ 0