Consolidated Statements 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 ($)	Accumulated Other Comprehensive (Loss) Income [Member] USD ($)	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	$ 4,304	$ 2	$ 3,325	$ 1,040	$ (63)	$ 1,502		$ 705	$ 797	$ 852		$ 347	$ 505	$ 802	$ 26	$ 576	$ 200
Balance, Shares at Dec. 31, 2011		227,500,190					100				1,000				8,546,017
Net Income (loss)	285			285		126			126	73			73	35			35
Other comprehensive income (loss)	15				15
Capital contribution from Parent						50		50		60		60
Dividends on common stock	(248)			(248)		(35)			(35)					(35)			(35)
Issuance of common stock:
Original issue shares, net	19		19
Original issue shares, net, shares		854,060
DRP original shares	32		32
DRP original shares, shares	2,000,000	1,661,177
Net activity related to stock-based awards	7		7
Balance at Dec. 31, 2012	4,414	2	3,383	1,077	(48)	1,643		755	888	985		407	578	802	26		200
Balance, Shares at Dec. 31, 2012		230,015,427					100				1,000				8,546,017
Net Income (loss)	(430)					23				26				9
Balance at Mar. 31, 2013
Balance at Dec. 31, 2012	4,414	2	3,383	1,077	(48)	1,643		755	888	985			578	802	26	576	200
Balance, Shares at Dec. 31, 2012		230,015,427					100				1,000				8,546,017
Net Income (loss)	(212)			(212)		150			150	89			89	50			50
Other comprehensive income (loss)	14				14
Capital contribution from Parent						175		175						75		75
Dividends on common stock	(270)			(270)		(46)			(46)	(30)			(30)	(60)			(60)
Issuance of common stock:
Original issue shares, net	332	1	331
Original issue shares, net, shares		18,734,128
DRP original shares	30		30
DRP original shares, shares	2,000,000	1,575,343
Net activity related to stock-based awards	7		7
Balance at Dec. 31, 2013	4,315	3	3,751	595	(34)	1,922		930	992	1,044			637	867	26	651	190
Balance, Shares at Dec. 31, 2013	250,324,898	250,324,898				100	100			1,000	1,000			8,546,017	8,546,017
Balance at Sep. 30, 2013
Net Income (loss)	58					24				28				9
Balance at Dec. 31, 2013	4,315					1,922				1,044				867	26
Balance, Shares at Dec. 31, 2013	250,324,898					100	100			1,000	1,000			8,546,017	8,546,017
Net Income (loss)	75					32				37				10
Balance at Mar. 31, 2014
Balance at Dec. 31, 2013	4,315	3	3,751	595	(34)	1,922		930	992	1,044		407	637	867	26		190
Balance, Shares at Dec. 31, 2013	250,324,898	250,324,898				100	100			1,000	1,000			8,546,017	8,546,017
Net Income (loss)	242			242		171			171	104			104	45			45
Other comprehensive income (loss)	(12)				(12)
Capital contribution from Parent						80		80		130		130
Dividends on common stock	(272)			(272)		(86)			(86)	(100)			(100)	(26)			(26)
Issuance of common stock:
Original issue shares, net	14		14
Original issue shares, net, shares		1,310,276
DRP original shares	28		28
DRP original shares, shares	1,000,000	1,122,575
Net activity related to stock-based awards	7		7
Net activity related to stock-based awards, shares		(29,065)
Balance at Dec. 31, 2014	4,322	3	3,800	565	(46)	2,087		1,010	1,077	1,178		537	641	886	26	651	209
Balance, Shares at Dec. 31, 2014	252,728,684	252,728,684				100	100			1,000	1,000			8,546,017	8,546,017
Balance at Sep. 30, 2014
Net Income (loss)	35					26				25				6
Balance at Dec. 31, 2014	$ 4,322					$ 2,087				$ 1,178				$ 886	$ 26	$ 651
Balance, Shares at Dec. 31, 2014	252,728,684					100	100			1,000	1,000			8,546,017	8,546,017