Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Jan. 01, 2021
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings/Undistributed earnings (losses)	$ 4,028		$ 16,942
Deferred income taxes and unamortized investment tax credits	11,089		10,611
Net income (loss)	598	$ (264)
Atlantic City Electric Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings/Undistributed earnings (losses)	(8)		(15)
Deferred income taxes and unamortized investment tax credits	692		682
Net income (loss)	26	14
Pepco Holdings LLC [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings/Undistributed earnings (losses)	(182)		(210)
Deferred income taxes and unamortized investment tax credits	2,723		$ 2,675
Net income (loss)	130	128
Atlantic City Electric Company [Member] | Atlantic City Electric Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings/Undistributed earnings (losses)				$ 8
Regulatory Liabilities				11
Deferred income taxes and unamortized investment tax credits				$ 3
Net income (loss)		$ 1
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 8