Consolidated Statement Of Equity (USD $) In Millions, except Share data	Total USD ($)	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, 2012	$ 4,446	$ 2	$ 3,383	$ 1,109	$ (48)	$ 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)	(102,933)	(6)
BALANCE at Mar. 31, 2013	$ 4,278	$ 2	$ 3,706	$ 612	$ (42)	$ 1,841		$ 930	$ 911	$ 1,011		$ 407	$ 604	$ 811	$ 26	$ 576	$ 209
Common Stock, Shares, Outstanding, Ending Balance at Mar. 31, 2013	248,551,381	248,551,381				100	100			1,000	1,000			8,546,017	8,546,017