Stock Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Shares Subject to Option
Balance at January 1, 2020 (in shares)		33,855,948
Options granted (in shares)		2,314,790
Options exercised (in shares)	[1]	(4,210,414)
Options canceled (in shares)		(262,968)
Balance at March 31, 2020 (in shares)		31,697,356	33,855,948
Weighted- Average Exercise or Grant Price Per Share
Balance at January 1, 2020 (in dollars per share)		$ 36.19
Options granted (in dollars per share)		58.97
Options exercised (in dollars per share)	[1]	28.62
Options canceled (in dollars per share)		41.20
Balance at March 31, 2020 (in dollars per share)		$ 38.31	$ 36.19
Average Remaining Contractual Term
Average remaining contractual term		6 years	5 years
Aggregate Intrinsic Value
Aggregate intrinsic value		$ 378	$ 640
Aggregate intrinsic value options exercised	[1]	120
Cash received from options exercised		119
Actual tax benefit realized and recorded in the provision for income taxes for the tax deductions from the option exercises		$ 17
Annual grant to eligible employees
Shares Subject to Option
Options granted (in shares)		2,280,440
Weighted- Average Exercise or Grant Price Per Share
Options granted (in dollars per share)		$ 59.04
Additional options issued
Shares Subject to Option
Options granted (in shares)		34,350
Weighted- Average Exercise or Grant Price Per Share
Options granted (in dollars per share)		$ 54.59

[1] Cash received from options exercised was $119 million in the three months ended March 31, 2020. The actual tax benefit realized and recorded in the provision for income taxes for the tax deductions from the option exercises totaled $17 million in the three months ended March 31, 2020.