Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance		$ 48	$ (2)
Other Comprehensive Income (Loss) before Reclassifications		(1)	(1)
Accumulated Other Comprehensive Income (Loss), Ending balance		46	(3)
Pension and Retiree Health and Welfare Benefit Items [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance	[1]	50	0
Other Comprehensive Income (Loss) before Reclassifications	[1]	0	0
Accumulated Other Comprehensive Income (Loss), Ending balance	[1]	49	0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts reclassified from AOCI		(1)	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and Retiree Health and Welfare Benefit Items [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts reclassified from AOCI	[1]	(1)	0
Equity Method Investee [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning balance		(2)	(2)
Other Comprehensive Income (Loss) before Reclassifications		(1)	(1)
Accumulated Other Comprehensive Income (Loss), Ending balance		(3)	(3)
Equity Method Investee [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts reclassified from AOCI		$ 0	$ 0

[1] Amounts are net of tax.