Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 12,805	$ 11,392
Other comprehensive income (loss) before reclassifications	2	9
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(11)	(10)
Ending balance	13,021	11,596
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(624)	(629)
Other comprehensive income (loss) before reclassifications	(12)	2
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(2)	0
Ending balance	(638)	(627)
Unrealized gain (loss) on forward contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	8
Other comprehensive income (loss) before reclassifications	10
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(9)
Ending balance	9
Unrealized gain (loss) on forward contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		23
Other comprehensive income (loss) before reclassifications		13
Amounts reclassified from accumulated other comprehensive income (loss) into earnings		(11)
Ending balance		25
Unrealized gain (loss) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3)	5
Other comprehensive income (loss) before reclassifications	4	(6)
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	0	1
Ending balance	1	0
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(619)	(601)
Ending balance	$ (628)	$ (602)