Consolidated Statement of Equity (USD $) In Millions, except Share data	Total USD ($)	Common Stock [Member] USD ($)	Premium on Stock [Member] USD ($)	Accumulated Other Comprehensive (Loss) Income [Member] USD ($)	Retained Earnings [Member] USD ($)	Potomac Electric Power Co [Member] USD ($)	Potomac Electric Power Co [Member] Common Stock [Member]	Potomac Electric Power Co [Member] Premium on Stock [Member] USD ($)	Potomac Electric Power Co [Member] Retained Earnings [Member] USD ($)	Delmarva Power & Light Co/De [Member] USD ($)	Delmarva Power & Light Co/De [Member] Common Stock [Member]	Delmarva Power & Light Co/De [Member] Premium on Stock [Member] USD ($)	Delmarva Power & Light Co/De [Member] Retained Earnings [Member] USD ($)	Atlantic City Electric Co [Member] USD ($)	Atlantic City Electric Co [Member] Common Stock [Member] USD ($)	Atlantic City Electric Co [Member] Premium on Stock [Member] USD ($)	Atlantic City Electric Co [Member] Retained Earnings [Member] USD ($)
BALANCE at Dec. 31, 2012	$ 4,414	$ 2	$ 3,383	$ (48)	$ 1,077	$ 1,643		$ 755	$ 888	$ 985		$ 407	$ 578	$ 802	$ 26	$ 576	$ 200
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2012	230,015,427	230,015,427				100	100			1,000	1,000			8,546,017	8,546,017
Net (loss) income	(430)				(430)	23			23	26			26	9			9
Other comprehensive income	6			6
Capital contribution from Parent						175		175
Dividends on common stock	(67)				(67)
Original issue shares, net	321		321
Original issue shares, net, shares		18,268,100
Shareholder DRP original shares, value	8		8
Shareholder DRP original shares, shares		370,787
Net activity related to stock-based awards	(6)		(6)
Net activity related to stock-based awards, shares		(102,933)
BALANCE at Mar. 31, 2013	4,246	2	3,706	(42)	580	1,841		930	911	1,011		407	604	811	26		209
Common Stock, Shares, Outstanding, Ending Balance at Mar. 31, 2013		248,551,381					100				1,000				8,546,017
BALANCE at Dec. 31, 2012	4,414					1,643				985		407		802	26	576
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2012	230,015,427					100	100			1,000	1,000			8,546,017	8,546,017
Net (loss) income	(270)					126				61				41
BALANCE at Sep. 30, 2013	4,302					1,898		930		1,016		407		893	26	651
Common Stock, Shares, Outstanding, Ending Balance at Sep. 30, 2013	249,713,980					100	100			1,000	1,000			8,546,017	8,546,017
BALANCE at Mar. 31, 2013	4,246	2	3,706	(42)	580	1,841			911	1,011		407	604	811	26	576	209
Common Stock, Shares, Outstanding, Beginning Balance at Mar. 31, 2013		248,551,381					100				1,000				8,546,017
Net (loss) income	42				42	37			37	12			12	7			7
Other comprehensive income	1			1
Capital contribution from Parent														75		75
Dividends on common stock	(67)				(67)	(15)			(15)	(20)			(20)
Original issue shares, net	2		2
Original issue shares, net, shares		91,424
Shareholder DRP original shares, value	7		7
Shareholder DRP original shares, shares		364,312
Net activity related to stock-based awards	5		5
Net activity related to stock-based awards, shares		102,933
BALANCE at Jun. 30, 2013	4,236	2	3,720	(41)	555	1,863		930	933	1,003		407	596	893	26	651	216
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2013		249,110,050					100				1,000				8,546,017
Net (loss) income	118				118	66			66	23			23	25			25
Other comprehensive income	1			1
Dividends on common stock	(67)				(67)	(31)			(31)	(10)			(10)	(25)			(25)
Original issue shares, net	3		3
Original issue shares, net, shares		189,408
Shareholder DRP original shares, value	8		8
Shareholder DRP original shares, shares		414,522
Net activity related to stock-based awards	3		3
BALANCE at Sep. 30, 2013	$ 4,302	$ 2	$ 3,734	$ (40)	$ 606	$ 1,898		$ 930	$ 968	$ 1,016		$ 407	$ 609	$ 893	$ 26	$ 651	$ 216
Common Stock, Shares, Outstanding, Ending Balance at Sep. 30, 2013	249,713,980	249,713,980				100	100			1,000	1,000			8,546,017	8,546,017