Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance		$ (2)	$ 245
Other Comprehensive Income (Loss) before Reclassifications		(1)	4
Amounts reclassified from accumulated other comprehensive income (loss)		0	(1)
Accumulated Other Comprehensive Income (Loss), Ending balance		(3)	248
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance	[1]	0	251
Other Comprehensive Income (Loss) before Reclassifications	[1]	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	(1)
Accumulated Other Comprehensive Income (Loss), Ending balance	[1]	0	250
Equity Method Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance		(2)	(6)
Other Comprehensive Income (Loss) before Reclassifications		(1)	4
Amounts reclassified from accumulated other comprehensive income (loss)		0	0
Accumulated Other Comprehensive Income (Loss), Ending balance		$ (3)	$ (2)

[1] Amounts are net of tax.