Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION - Summary of Stock Options Activity (Details)

v3.20.4
STOCK-BASED COMPENSATION - Summary of Stock Options Activity (Details) - Equity Option - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Number of Shares    
Outstanding beginning balance (shares) 28,105  
Granted (shares) 6,210  
Exercised (shares) (612)  
Forfeited (shares) (8,478)  
Outstanding ending balance (shares) 25,225 28,105
Exercisable (shares) 22,254  
Vested or expected to vest (shares) 25,225  
Weighted Average Exercise Price    
Outstanding beginning balance (USD per share) $ 0.80  
Granted (USD per share) 0.41  
Exercised (USD per share) 0.37  
Forfeited (USD per share) 0.91  
Outstanding ending balance (USD per share) 0.48 $ 0.80
Exercisable (USD per share) 0.46  
Vested or expected to vest (USD per share) $ 0.48  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]    
Outstanding balance, weighted average remaining contract term (in years) 5 years 8 months 12 days 5 years 4 months 24 days
Options exercisable, weighted average remaining contract term (in years) 5 years 3 months 18 days  
Options vested or expected to vest, weighted average remaining contract term (in years) 5 years 8 months 12 days  
Outstanding beginning balance, aggregate intrinsic value $ 12,335  
Outstanding ending balance, aggregate intrinsic value 2,186 $ 12,335
Options exercisable, aggregate intrinsic value 2,010  
Options vested or expected to vest, aggregate intrinsic value $ 2,186