Stockholders' Equity - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 22,525
Net current period other comprehensive income (loss)	$ (47)	$ 15	(62)	$ 37
Ending balance	17,445		17,445
Foreign Currency Translation, Net of Tax
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			53	47
Net unrealized gain (loss)			(12)	(19)
Reclassifications to net income			0	0
Net current period other comprehensive income (loss)			(12)	(19)
Ending balance	41	28	41	28
Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1	(52)
Net unrealized gain (loss)			42	53
Reclassifications to net income			(17)	0
Net current period other comprehensive income (loss)			25	53
Ending balance	26	1	26	1
Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			31	85
Net unrealized gain (loss)			(25)	99
Reclassifications to net income			(50)	(96)
Net current period other comprehensive income (loss)			(75)	3
Ending balance	(44)	88	(44)	88
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			85	80
Net unrealized gain (loss)			5	133
Reclassifications to net income			(67)	(96)
Net current period other comprehensive income (loss)	(47)	15	(62)	37
Ending balance	$ 23	$ 117	$ 23	$ 117