Stockholders' Equity - Activity Related to Stock Option Plans (Details)	9 Months Ended
	Sep. 30, 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)	1,217,273
Options outstanding, number of shares granted (in shares)	(1,217,273)
Options outstanding, number of shares, exercised (in shares)	(1,239,343)
Options outstanding, number of shares expired (in shares)	(5,343)
Shares available for grant, ending balance (in shares)	20,484,812
Options outstanding, number of shares, ending balance (in shares)	18,649,397
Options vested and exercisable, number of shares, ending balance (in shares)	18,649,397
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	531.34
Options outstanding, weighted-average exercise price, exercised (dollars per share) | $ / shares	81.47
Options expired, weighted-average exercise price (dollars per share) | $ / shares	32.57
Options outstanding, weighted-average exercise price, ending balance (dollars per share) | $ / shares	199.74
Options outstanding, weighted-average exercise price, vested and exercisable (dollars per share) | $ / shares	$ 199.74