Dispositions (Selected Information Regarding the Results of Operations of Peoples) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2010		Dec. 31, 2009
Operating revenue	$ 67		$ 432
Income (loss) before income taxes	(134)	[1]	42	[2]
Income tax charge related to re-establishment of certain regulatory assets			$ 22

[1] Includes a loss and other charges related to the sale of Peoples.

[2] Includes the impact of a $22 million charge due to a reduction of the previously established regulatory asset and a loss and other charges related to the sale.