CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 1,795	$ 1,401	$ 1,228
Other comprehensive income (loss), net of reclassification adjustments:
Foreign currency translation	43	(15)	(37)
Unrealized (losses) gains on investments, net	(7)	11	(16)
Tax benefit (expense) on unrealized gains/losses on investments, net	1	(1)	3
Change in unrealized gains/losses on hedging activities, net	(242)	74	(69)
Tax benefit (expense) on unrealized gains/losses on hedging activities, net	4	(1)	0
Other comprehensive (loss) income, net of tax	(201)	68	(119)
Comprehensive income	$ 1,594	$ 1,469	$ 1,109