Intangible Assets and Goodwill Accumulated Amortization Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Amortization [Roll Forward]
Balance at January 1	$ 400	$ 283
Amortization	117	117	$ 70
Foreign currency translation and other	51	0
Balance at December 31	$ 568	$ 400	$ 283