Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 12,805	$ 11,392
Other comprehensive income (loss) before reclassifications	(1)	11
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(14)	(18)
Ending balance	13,682	11,977
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(624)	(629)
Other comprehensive income (loss) before reclassifications	(9)	1
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(2)	0
Ending balance	(635)	(628)
Unrealized gain (loss) on forward contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	8	23
Other comprehensive income (loss) before reclassifications	3	11
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(12)	(17)
Ending balance	(1)	17
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	5	(1)
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	0	(1)
Ending balance	2	3
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(619)	(601)
Ending balance	$ (634)	$ (608)