Stock-Based Compensation - Stock Options (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares
Stock Based Compensation
RSUs granted (in shares)	(2,208,000)
RSUs forfeited/cancelled (in shares)	291,000
Employee and non-employee stock options
Stock Based Compensation
Shares available for grant, beginning balance	3,148,000
Additional shares authorized	3,446,000
Options granted (in shares)	(391,000)
Options forfeited (in shares)	33,000
Shares available for grant, end balance	4,319,000	3,148,000
Number of shares
Outstanding, beginning balance (in shares)	6,707,000
Options granted (in shares)	391,000
Options exercised (in shares)	(1,165,000)
Options forfeited (in shares)	(33,000)
Outstanding, end balance (in shares)	5,900,000	6,707,000
Exercisable (in shares)	4,977,000
Vested and expected to vest (in shares)	5,840,000
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 11.19
Granted (in dollars per share) | $ / shares	104.03
Exercised (in dollars per share) | $ / shares	10.14
Forfeited (in dollars per share) | $ / shares	15.00
Outstanding, end balance (in dollars per share) | $ / shares	17.54	$ 11.19
Exercisable (in dollars per share) | $ / shares	10.65
Vested and expected to vest (in dollars per share) | $ / shares	$ 17.17
Additional disclosures
Weighted average contractual term, options outstanding	5 years 4 months 24 days	6 years 14 days
Exercisable (in years)	4 years 10 months 24 days
Vested and expected to vest (in years)	5 years 4 months 13 days
Aggregate intrinsic value, options outstanding | $	$ 451,505	$ 592,468
Aggregate intrinsic value, options exercisable | $	411,841
Aggregate intrinsic value, vested and expected to vest | $	449,026
Aggregate intrinsic value, options exercised | $	97,000	184,700	$ 70,000
Fair value, options vested | $	$ 46,000	$ 52,500,000	$ 11,000
Weighted-average grant date fair value, options granted | $ / shares	$ 104.03	$ 27.70	$ 8.01
Non-employee stock options
Stock Based Compensation
Options granted (in shares)	(31,553)
Number of shares
Options granted (in shares)	31,553
Additional disclosures
Options unvested (in shares)	730
Restricted stock units
Stock Based Compensation
RSUs granted (in shares)	(2,208)
RSUs forfeited/cancelled (in shares)	291