Income Taxes Income Taxes (Reconcilation of Valuation Allowance of Deferred Tax Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Acquisitions	$ 40	$ 0	$ 0
Valuation Allowance of Deferred Tax Assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	248	427	349
Change in assessment (a)	17	(5)	(4)
Current year operations	38	39	100
Foreign currency and other	(32)	(213)	(18)
Balance at end of year	311	$ 248	$ 427
Deferred Tax Asset, Foreign Currency Adjustments
Movement in Valuation Allowances and Reserves [Roll Forward]
Net operating loss	$ 176