Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 12,805	$ 11,392
Other comprehensive income (loss) before reclassifications	(8)	29
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	5	(47)
Ending balance	15,037	12,805
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(619)	(601)
Ending balance	(622)	(619)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(624)	(629)
Other comprehensive income (loss) before reclassifications	37	5
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	(2)	0
Ending balance	(589)	(624)
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	(6)	0
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	4	(8)
Ending balance	(5)	(3)
Unrealized gain (loss) on forward contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	8	23
Other comprehensive income (loss) before reclassifications	(39)	24
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	3	(39)
Ending balance	$ (28)	$ 8