Consolidated Statement Of Equity (USD $) In Millions, except Share data, unless otherwise specified	Total USD ($)	Common Stock [Member] USD ($)	Premium On Stock [Member] USD ($)	Retained Earnings [Member] USD ($)	Accumulated Other Comprehensive Loss [Member] USD ($)	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, 2011	$ 4,336	$ 2	$ 3,325	$ 1,072	$ (63)	$ 1,502		$ 705	$ 797	$ 852		$ 347	$ 505	$ 802	$ 26	$ 576	$ 200
Common Stock, Shares, Outstanding at Dec. 31, 2011	227,500,190	227,500,190				100	100			1,000	1,000			8,546,017	8,546,017
Net income	68			68		24			24	21			21	2			2
Other comprehensive income	8				8
Dividends on common stock	(61)			(61)
Issuance of common stock:
Original issue shares, net	9		9
Original issue shares, net, shares		319,037
Shareholder DRP original shares, value	8		8
Shareholder DRP original shares, shares		424,888
Net activity related to stock-based awards	(2)		(2)
BALANCE at Mar. 31, 2012	4,366	2	3,340	1,079	(55)	1,526			821	873		347	526	804	26	576	202
Common Stock, Shares, Outstanding at Mar. 31, 2012		228,244,115					100				1,000				8,546,017
BALANCE at Dec. 31, 2011	4,336					1,502		705		852		347		802	26	576
Common Stock, Shares, Outstanding at Dec. 31, 2011	227,500,190					100	100			1,000	1,000			8,546,017	8,546,017
Net income	130					51				34				16
BALANCE at Jun. 30, 2012	4,384					1,603				886		347		803	26	576
Common Stock, Shares, Outstanding at Jun. 30, 2012	228,851,815					100	100			1,000	1,000			8,546,017	8,546,017
BALANCE at Mar. 31, 2012	4,366	2	3,340	1,079	(55)	1,526		705	821	873		347	526	804	26	576	202
Common Stock, Shares, Outstanding at Mar. 31, 2012		228,244,115					100				1,000				8,546,017
Net income	62			62		27			27	13			13	14			14
Other comprehensive income	4				4
Capital Contribution						50		50
Dividends on common stock	(62)			(62)										(15)			(15)
Issuance of common stock:
Original issue shares, net	3		3
Original issue shares, net, shares		186,820
Shareholder DRP original shares, value	8		8
Shareholder DRP original shares, shares		420,880
Net activity related to stock-based awards	3		3
BALANCE at Jun. 30, 2012	$ 4,384	$ 2	$ 3,354	$ 1,079	$ (51)	$ 1,603		$ 755	$ 848	$ 886		$ 347	$ 539	$ 803	$ 26	$ 576	$ 201
Common Stock, Shares, Outstanding at Jun. 30, 2012	228,851,815	228,851,815				100	100			1,000	1,000			8,546,017	8,546,017