Revenue from Contracts with Customers - Change in Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	$ 130	$ 131	$ 133	$ 98	$ 100	$ 101
Revenues recognized	(2)	(1)	(2)	(2)	(2)	(1)
Ending Balance - Contract Liabilities	128	130	131	96	98	100
Pepco Holdings LLC
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	130	131	133	98	100	101
Revenues recognized	(2)	(1)	(2)	(2)	(2)	(1)
Ending Balance - Contract Liabilities	128	130	131	96	98	100
Potomac Electric Power Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	104	105	107	78	80	81
Revenues recognized	(2)	(1)	(2)	(1)	(2)	(1)
Ending Balance - Contract Liabilities	102	104	105	77	78	80
Delmarva Power and Light Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	13	13	13	10	10	10
Revenues recognized	0	0	0	0	0	0
Ending Balance - Contract Liabilities	13	13	13	10	10	10
Atlantic City Electric Company
Contract Liabilities [Roll Forward]
Beginning Balance - Contract Liabilities	13	13	13	10	10	10
Revenues recognized	0	0	0	(1)	0	0
Ending Balance - Contract Liabilities	$ 13	$ 13	$ 13	$ 9	$ 10	$ 10