STOCK BASED COMPENSATION - Options (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Stock-based compensation    
Options granted (in shares) 406,752 1,105,604
Stock-based compensation expense $ 11,177 $ 8,026
Unrecognized stock-based compensation balance for unvested options $ 18,800  
Weighted-average fair value of options granted (in dollars per share) $ 8.43 $ 18.84
Options    
Stock-based compensation    
Stock-based compensation expense $ 9,300 $ 7,100
Unrecognized stock-based compensation balance for unvested options expected to be recognized (in years) 2 years 4 months 24 days