Revenue from Contracts with Customers - Change in Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended
Sep. 30, 2026	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	$ 117	$ 118	$ 119	$ 123	$ 126	$ 127
Revenues recognized	(2)	(1)	(1)	(1)	(3)	(1)
Ending Balance - Contract Liabilities	115	117	118	122	123	126
Pepco Holdings LLC
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	117	118	119	123	126	127
Revenues recognized	(2)	(1)	(1)	(1)	(3)	(1)
Ending Balance - Contract Liabilities	115	117	118	122	123	126
Potomac Electric Power Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	93	94	95	98	100	101
Revenues recognized	(2)	(1)	(1)	(1)	(2)	(1)
Ending Balance - Contract Liabilities	91	93	94	97	98	100
Delmarva Power and Light Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	12	12	12	12	13	13
Revenues recognized	0	0	0	0	(1)	0
Ending Balance - Contract Liabilities	12	12	12	12	12	13
Atlantic City Electric Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	12	12	12	13	13	13
Revenues recognized	0	0	0	0	0	0
Ending Balance - Contract Liabilities	$ 12	$ 12	$ 12	$ 13	$ 13	$ 13