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, 2013	$ 4,315	$ 3	$ 3,751	$ 595	$ (34)	$ 1,922		$ 930	$ 992	$ 1,044		$ 407	$ 637	$ 867	$ 26	$ 651	$ 190
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2013	250,324,898	250,324,898				100	100			1,000	1,000			8,546,017	8,546,017
Net income	75			75		32			32	37			37	10			10
Other comprehensive income (loss)	1				1
Capital contribution from Parent						80		80
Dividends on common stock	(68)			(68)						(20)			(20)	(26)			(26)
Issuance of common stock:
Original issue shares, net	3		3
Original issue shares, net, shares		284,022
Shareholder DRP original issue shares	8		8
Shareholder DRP original issue shares, shares		374,003
Net activity related to stock-based awards	2		2
BALANCE at Mar. 31, 2014	4,336	3	3,764	602	(33)	2,034		1,010	1,024	1,061			654	851	26	651	174
Common Stock, Shares, Outstanding, Ending Balance at Mar. 31, 2014		250,982,923					100				1,000				8,546,017
BALANCE at Dec. 31, 2013	4,315					1,922				1,044		407		867	26	651
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2013	250,324,898					100	100			1,000	1,000			8,546,017	8,546,017
Net income	207					145				79				39
Other comprehensive income (loss)	1
BALANCE at Sep. 30, 2014	4,362					2,101		1,010		1,233		537		880	26	651
Common Stock, Shares, Outstanding, Ending Balance at Sep. 30, 2014	251,879,809					100	100			1,000	1,000			8,546,017	8,546,017
BALANCE at Mar. 31, 2014	4,336	3	3,764	602	(33)	2,034			1,024	1,061		407	654	851	26	651	174
Common Stock, Shares, Outstanding, Beginning Balance at Mar. 31, 2014		250,982,923					100				1,000				8,546,017
Net income	53			53		46			46	19			19	6			6
Other comprehensive income (loss)	(2)				(2)
Capital contribution from Parent										130		130
Dividends on common stock	(68)			(68)		(46)			(46)
Issuance of common stock:
Original issue shares, net	4		4
Original issue shares, net, shares		252,240
Shareholder DRP original issue shares	7		7
Shareholder DRP original issue shares, shares		263,245
Net activity related to stock-based awards	5		5
BALANCE at Jun. 30, 2014	4,335	3	3,780	587	(35)	2,034		1,010	1,024	1,210		537	673	857	26	651	180
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2014		251,498,408					100				1,000				8,546,017
Net income	79			79		67			67	23			23	23			23
Other comprehensive income (loss)	2				2
Dividends on common stock	(68)			(68)
Issuance of common stock:
Original issue shares, net	3		3
Original issue shares, net, shares		136,096
Shareholder DRP original issue shares	7		7
Shareholder DRP original issue shares, shares		245,305
Net activity related to stock-based awards	4		4
Net activity related to stock-based awards, shares
BALANCE at Sep. 30, 2014	$ 4,362	$ 3	$ 3,794	$ 598	$ (33)	$ 2,101		$ 1,010	$ 1,091	$ 1,233		$ 537	$ 696	$ 880	$ 26	$ 651	$ 203
Common Stock, Shares, Outstanding, Ending Balance at Sep. 30, 2014	251,879,809	251,879,809				100	100			1,000	1,000			8,546,017	8,546,017