Commitments And Contingencies (Rate Proceedings) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	6 Months Ended	0 Months Ended			1 Months Ended			6 Months Ended	0 Months Ended	1 Months Ended		6 Months Ended
	Oct. 31, 2010	Jun. 30, 2011	Jul. 08, 2011 Delmarva Power & Light Co/De [Member]	May 25, 2011 Delmarva Power & Light Co/De [Member]	May 25, 2011 Delmarva Power & Light Co/De [Member]	Feb. 28, 2011 Delmarva Power & Light Co/De [Member]	Dec. 31, 2010 Delmarva Power & Light Co/De [Member]	Aug. 31, 2010 Delmarva Power & Light Co/De [Member]	Jun. 30, 2011 Delmarva Power & Light Co/De [Member]	Feb. 09, 2011 DCPSC [Member]	Aug. 31, 2010 Maryland [Member]	Dec. 31, 2009 Maryland [Member]	Jun. 30, 2011 Maryland [Member]
Effect of proposed change on gas cost rate	0.10%
Return on equity, percentage				10.00%			10.75%		11.00%	10.00%	9.83%	10.75%
Rate increase implemented						$ 7.7		$ 2.5		$ 5.8
Proposed rate increase			42
Requested rate change					12.2		17.8		10.2			40.0	28.2
Approved rate change											7.8
Increase in annual revenue if rate change occurs		$ 8.5