Revenue from Contracts with Customers - Change in Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	$ 126	$ 127	$ 131	$ 133
Revenues recognized	(3)	(1)	(1)	(2)
Ending Balance - Contract Liabilities	123	126	130	131
Pepco Holdings LLC
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	126	127	131	133
Revenues recognized	(3)	(1)	(1)	(2)
Ending Balance - Contract Liabilities	123	126	130	131
Potomac Electric Power Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	100	101	105	107
Revenues recognized	(2)	(1)	(1)	(2)
Ending Balance - Contract Liabilities	98	100	104	105
Delmarva Power and Light Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	13	13	13	13
Revenues recognized	(1)	0	0	0
Ending Balance - Contract Liabilities	12	13	13	13
Atlantic City Electric Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	13	13	13	13
Revenues recognized	0	0	0	0
Ending Balance - Contract Liabilities	$ 13	$ 13	$ 13	$ 13