Annual report pursuant to Section 13 and 15(d)

SHARE-BASED COMPENSATION - Activity of Stock Options (Details)

v3.21.1
SHARE-BASED COMPENSATION - Activity of Stock Options (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Stock Options    
Outstanding, beginning balance (in shares) 1,195,544  
Granted (in shares) 121,291  
Exercised (in shares) (88,706)  
Forfeited (in shares) (331,241)  
Outstanding, ending balance (in shares) 896,888 1,195,544
Vested and expected to vest (in shares) 885,607  
Vested and exercisable (in shares) 419,498  
Weighted-Average Exercise Price    
Outstanding, beginning price (in dollars per share) $ 14.18  
Granted price (in dollars per share) 6.71  
Exercised price (in dollars per share) 0.24  
Forfeited price (in dollars per share) 11.86  
Outstanding, ending price (in dollars per share) 5.22 $ 14.18
Vested and expected to vest (in dollars per share) 5.60  
Vested and exercisable (in dollars per share) $ 6.80  
Weighted-Average Remaining Contractual Term (Years) and Aggregate Intrinsic Value    
Outstanding term 3 years 11 months 15 days 3 years 2 months 15 days
Granted term 3 years 7 months 20 days  
Vested and expected to vest term 3 years 11 months 19 days  
Vested and exercisable term 3 years 9 months 10 days  
Outstanding $ 2,889 $ 3,194
Exercised 705  
Vested and expected to vest 2,906  
Vested and exercisable $ 944  
RSU    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Cost not yet recognized, period for recognition 2 years  
Weighted Average | RSU    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Cost not yet recognized, period for recognition 1 year 3 months 18 days 0 years