Stockholders' Equity - Activity Related to Stock Option Plans (Details)	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares available for grant, beginning balance (in shares)	21,702,085
Options outstanding, number of shares, beginning balance (in shares)	18,676,810
Options outstanding, number of shares granted (in shares)	(400,126)
Options outstanding, number of shares granted (in shares)	400,126
Options outstanding, number of shares, exercised (in shares)	(488,471)
Options outstanding, number of shares expired (in shares)	(4,648)
Shares available for grant, ending balance (in shares)	21,301,959
Options outstanding, number of shares, ending balance (in shares)	18,583,817
Options vested and exercisable, number of shares, ending balance (in shares)	18,583,817
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding, weighted-average exercise price, beginning balance (dollars per share) | $ / shares	$ 170.23
Options outstanding, weighted-average exercise price, granted (dollars per share) | $ / shares	537.47
Options outstanding, weighted-average exercise price, exercised (dollars per share) | $ / shares	92.45
Options expired, weighted-average exercise price (dollars per share) | $ / shares	30.30
Options outstanding, weighted-average exercise price, ending balance (dollars per share) | $ / shares	180.22
Options outstanding, weighted-average exercise price, vested and exercisable (dollars per share) | $ / shares	$ 180.22