Discontinued Operations (Operating Results of Conectiv Energy) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended							12 Months Ended
	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
(Loss) income from discontinued operations, net of income taxes	$ (4)	$ (1)	$ 2	$ 19	$ (4)	$ (130)	$ 8	$ (3)	$ (107)	$ 12
Conectiv Energy [Member]
(Loss) income from operations of discontinued operations, net of income taxes								(1)	6	12
Net losses from dispositions of assets and businesses of discontinued operations, net of income taxes								(2)	(113)
(Loss) income from discontinued operations, net of income taxes								$ (3)	$ (107)	$ 12