Goodwill and Other Intangible Assets and Liablities Intangible Assets and Liabilities Carrying Amount (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	$ 647	$ 661
Intangible assets, accumulated amortization	253	231
Intangible liabilities, gross carrying amount	1,403	1,403
Intangible liabilities, accumulated amortization	932	836
Amortization of Intangible Assets	36	39	$ 58
Amortization of intangible Liabilities	96	$ 100	$ 115
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of intangible assets, 2018	33
Amortization of intangible liabilities, 2018	90
Amortization of intangible assets, 2019	31
Amortization of intangible liabilities, 2019	27
Amortization of intangible assets, 2020	31
Amortization of intangible liabilities, 2020	26
Amortization of intangible assets, 2021	31
Amortization of intangible liabilities, 2021	24
Amortization of intangible assets, 2022	31
Amortization of intangible liabilities, 2022	$ 23