Stockholders' Equity - Summary of Activity under 2008 Plan and 2018 Plan (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Number of Options (In Thousands)
Beginning balance (in shares)	10,485
Options grants (in shares)	3,007
Options exercised (in shares)	(125)
Options cancelled (in shares)	(127)
Ending balance (in shares)	13,240	10,485
Vested and expected to vest (in shares)	12,727
Exercisable (in shares)	8,603
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 15.79
Options granted (in dollars per share)	15.26
Options exercised (in dollars per share)	5.36
Options cancelled (in dollars per share)	21.57
Ending balance (in dollars per share)	15.71	$ 15.79
Vested and expected to vest, weighted average exercise price (in dollars per share)	15.56
Exercisable, weighted average exercise price (in dollars per share)	$ 13.13
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Life (In Years)	7 years 2 months 19 days	6 years 8 months 4 days
Vested and expected to vest, weighted average remaining contractual life	7 years 1 month 20 days
Exercisable, weighted average remaining contractual life	6 years
Aggregate intrinsic value	$ 35,840	$ 52,349
Vested and expected to vest, aggregate intrinsic value	35,799
Exercisable, aggregate intrinsic value	$ 35,691