STOCK-BASED COMPENSATION - Summary of Company's Stock Option Activity and Related Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Number of Stock Options Outstanding
Outstanding at beginning of period (in shares)	7,156,776
Option granted (in shares)	0
Options exercised (in shares)	(19,292)
Options cancelled or forfeited (in shares)	(133,995)
Outstanding at end of period (in shares)	7,003,489	7,156,776
Options exercisable (in shares)	6,117,485
Options vested and expected to vest (in shares)	6,938,310
Weighted- Average Exercise Price
Options outstanding at beginning of period (in USD per share)	$ 6.97
Options granted (in USD per share)	0
Options exercised (in USD per share)	2.91
Options cancelled or forfeited (in USD per share)	8.18
Options outstanding at end of period (in USD per share)	6.96	$ 6.97
Options exercisable (in USD per share)	7.06
Options vested and expected to vest (in USD per share)	$ 6.99
Weighted- Average Remaining Contractual Life (Years)
Options outstanding (in years)	5 years 10 months 24 days	6 years 1 month 6 days
Options exercisable (in years)	5 years 8 months 12 days
Options vested and expected to vest (in years)	5 years 9 months 18 days
Aggregate Intrinsic Value
Options outstanding	$ 2,651	$ 5,203
Options exercisable	2,038
Options vested and expected to vest	$ 2,560