Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, tax	$ (1)	$ (2)	$ 17	$ (15)
Unrealized gains (losses), tax	0	3	9	2
Reclassification adjustment for losses (gains) included in “Other income (expense), net,” tax	$ 0	$ 0	$ 0	$ 0