Goodwill and Other Asset Impairments (Details) - USD ($)		3 Months Ended	9 Months Ended
		Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 72,000,000
Goodwill, ending balance		$ 0	0
Operating Segments | East
Goodwill [Line Items]
Goodwill impairment charge, before tax		466,000,000	466,000,000
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]		72,000,000
Provisional goodwill recognized during the period	[2]		394,000,000
Goodwill impairment charge, before tax		(466,000,000)	(466,000,000)
Goodwill, ending balance	[1]	0	0
Accumulated impairment losses		$ 466,000,000	$ 466,000,000	$ 0

[1] There were no accumulated impairment losses related to goodwill at December 31, 2014 and $466 million at September 30, 2015.

[2] Recognized as a result of the acquisition of RJS Power. See Note 7 for additional information.