Consolidated Statements of Comprehensive Income (Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net Income (Loss)	$ 118	$ 112	$ (270)	$ 242
Other Comprehensive Income from Continuing Operations
Loss on treasury rate locks reclassified into income		1	1	1
Pension and other postretirement benefit plans	1	1	2	(4)
Other comprehensive (loss) income, before income taxes	1	2	3	(3)
Income tax expense (benefit) related to other comprehensive income		2	1	(1)
Other comprehensive income (loss) from continuing operations, net of income taxes	1		2	(2)
Other Comprehensive Income from Discontinued Operations, Net of Income Taxes		4	6	18
Comprehensive Income (Loss)	$ 119	$ 116	$ (262)	$ 258