Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Number of Stock Options
Beginning balance (in shares)	41,775,179
Granted (in shares)	7,962,442
Exercised (in shares)	(1,709,498)
Canceled or forfeited (in shares)	(321,796)
Ending balance (in shares)	47,706,327	41,775,179
Exercisable (in shares)	24,398,342
Weighted- Average Exercise Price Per Share
Beginning balance (in dollars per share)	$ 5.05
Granted (in dollars per share)	6.03
Exercised (in dollars per share)	1.49
Cancelled or forfeited (in dollars per share)	5.51
Ending balance (in dollars per share)	5.34	$ 5.05
Exercisable (in dollars per share)	$ 3.82
Weighted- Average Remaining Contractual Life (in years)
Options Outstanding	7 years 10 months 2 days	7 years 10 months 2 days
Options Exercisable	6 years 8 months 23 days
Aggregate Intrinsic Value (in thousands)
Options Outstanding	$ 51,890	$ 142,076
Options Exercisable	$ 48,645