STOCKHOLDERS' EQUITY - Additional information (Details)
 12 Months Ended
Apr. 12, 2021
USD ($)
shares
Jul. 24, 2020
USD ($)
$ / shares
shares
Apr. 20, 2020
USD ($)
Feb. 28, 2020
USD ($)
shares
Feb. 18, 2020
Jul. 22, 2019
USD ($)
shares
Jul. 09, 2019
USD ($)
Mar. 04, 2019
USD ($)
shares
Dec. 31, 2021
USD ($)
item
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Jul. 14, 2021
USD ($)
Jun. 30, 2019
shares
May 31, 2019
shares
Dec. 31, 2018
shares
Jul. 26, 2018
USD ($)
Stockholders Equity [Line Items]                                
Number of preferred stock authorized | shares                 5,000,000 5,000,000     5,000,000      
Number of common stock authorized | shares                 100,000,000 100,000,000     100,000,000 50,000,000    
Number of shares issued | shares                 4,301,869              
Aggregate registered amount for offerings                       $ 150,000,000       $ 150,000,000
Average selling price | $ / shares                 $ 6.53              
Net proceeds from issuance of stock                 $ 27,200,000              
Expenses incurred                 $ 90,000 $ 49,000            
Number of option granted | shares       1,114,325         2,051,980 1,579,106 1,557,300          
Grant date fair value of these unvested options                 $ 3,883,000              
Stock or Unit Option Plan Expense                 $ 1,070,000 $ 914,000            
Percentage of Milestone Activity Met by the Company 88.00%                              
Number of Long Term Incentive Plans | item                 2              
Allocated share-based compensation expense                 $ 4,021,000 3,514,000 $ 1,666,000          
Exercise price per share | $ / shares                 $ 4.19              
Risk free rate maximum                 1.39%              
Total unrecognized compensation cost related to stock options                 $ 5,932,000              
Amortized period                 41 months              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares | shares                 917,214              
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures                 $ 928,417 $ 657,780 $ 663,368          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares                 6,885,978 5,165,204 4,218,189       3,658,462  
Class of Warrant or Right, Outstanding | shares                 0              
Employees                                
Stockholders Equity [Line Items]                                
Number of option granted | shares 1,323,400                              
Grant date fair value of unvested options $ 7,042,000                              
Allocated share-based compensation expense                 $ 273,000              
Underwritten public offering                                
Stockholders Equity [Line Items]                                
Number of shares issued | shares   6,052,631                            
Average selling price | $ / shares   $ 9.50                            
Gross Proceeds from issuance of stock   $ 57,500,000                            
Net proceeds from issuance of stock   $ 53,800,000                            
Restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares                 91,750              
Stock Issued During Period, Value, Restricted Stock Award, Gross                 $ 713,868              
Vesting period                 4 years              
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures                 $ 178,000              
Restricted stock | First 43,000 restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares                 46,750              
Restricted stock | Second 43,000 restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares                 45,000              
Restricted stock | Second anniversary of the date of the grant | First 43,000 restricted stock                                
Stockholders Equity [Line Items]                                
Vesting percentage                 1.00%              
Restricted stock | Third anniversary of the date of the grant | First 43,000 restricted stock                                
Stockholders Equity [Line Items]                                
Vesting percentage                 1.00%              
Restricted stock | Fourth anniversary of the date of the grant | First 43,000 restricted stock                                
Stockholders Equity [Line Items]                                
Vesting percentage                 1.00%              
Option | Employees                                
Stockholders Equity [Line Items]                                
Number of option granted | shares           926,800                    
Grant date fair value of these unvested options           $ 4,294,000                    
Stock or Unit Option Plan Expense                 $ 667,000 $ 735,000            
Percentage of Milestone Activity Met by the Company         35.00%                      
Stock Option Plan One [Member]                                
Stockholders Equity [Line Items]                                
Common stock reserved for issuance | shares                 2,400,000              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares                 237,000              
Two Thousand Fourteen Stock Option Plan [Member]                                
Stockholders Equity [Line Items]                                
Common stock reserved for issuance | shares                 13,400,000              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares                 6,322,000              
March 4, 2019 Performance-Based Award | Restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares               22,220                
Stock Issued During Period, Value, Restricted Stock Award, Gross               $ 179,000                
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures                 $ 11,000 33,000            
March 4, 2019 Performance-Based Award | Restricted stock | On the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage               33.30%                
March 4, 2019 Performance-Based Award | Restricted stock | First anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage               33.30%                
March 4, 2019 Performance-Based Award | Restricted stock | Second anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage               33.30%                
July 24,2020 Offering | Underwritten public offering                                
Stockholders Equity [Line Items]                                
Number of shares issued | shares   6,052,631                            
Average selling price | $ / shares   $ 9.50                            
Gross Proceeds from issuance of stock   $ 57,500,000                            
Net proceeds from issuance of stock   $ 53,800,000                            
July 22, 2019 Performance-Based Award | Restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares           180,300                    
Stock Issued During Period, Value, Restricted Stock Award, Gross           $ 1,300,000                    
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures                 259,000 564,000            
July 22, 2019 Performance-Based Award | Restricted stock | On the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage           33.30%                    
July 22, 2019 Performance-Based Award | Restricted stock | First anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage           33.30%                    
July 22, 2019 Performance-Based Award | Restricted stock | Second anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage           33.30%                    
February 28 2020 Performance Based Award | Restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares       168,100                        
Stock Issued During Period, Value, Restricted Stock Award, Gross       $ 1,014,000                        
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures                 528,000 $ 619,000            
February 28 2020 Performance Based Award | Restricted stock | On the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage       33.30%                        
February 28 2020 Performance Based Award | Restricted stock | First anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage       33.30%                        
February 28 2020 Performance Based Award | Restricted stock | Second anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage       33.30%                        
April 12, 2021 Performance Based Award | Restricted stock                                
Stockholders Equity [Line Items]                                
Stock Issued During Period, Shares, Restricted Stock Award, Gross | shares 235,765                              
Stock Issued During Period, Value, Restricted Stock Award, Gross $ 2,120,000                              
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures $ 1,207,000                              
April 12, 2021 Performance Based Award | Restricted stock | On the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage 33.30%                              
April 12, 2021 Performance Based Award | Restricted stock | First anniversary of the date of the grant                                
Stockholders Equity [Line Items]                                
Vesting percentage 33.30%                              
Jefferies LLC and B. Riley FBR, Inc                                
Stockholders Equity [Line Items]                                
Number of shares issued | shares                   4,110,625 191,244          
aggregate offering price     $ 50,000,000       $ 25,000,000                  
Average selling price | $ / shares                   $ 6.64 $ 4.11          
Net proceeds from issuance of stock                   $ 26,500,000 $ 762,000          
Commission rate (as a percent)             3.00%                  
Jefferies Llc                                
Stockholders Equity [Line Items]                                
aggregate offering price                 $ 25,000,000              
Commission rate (as a percent)                 3.00%              
Exercise Price Ranging From 3.84 To 8.25                                
Stockholders Equity [Line Items]                                
Expected life of the stock option                     10 years          
Expected dividends                     0.00%          
Risk free interest rate, minimum                     1.40%          
Risk free rate maximum                     2.61%          
Exercise Price Ranging From 3.84 To 8.25 | Maximum                                
Stockholders Equity [Line Items]                                
Exercise price per share | $ / shares                     $ 8.25          
Expected volatility                     74.30%          
Exercise Price Ranging From 3.84 To 8.25 | Minimum                                
Stockholders Equity [Line Items]                                
Exercise price per share | $ / shares                     $ 3.84          
Expected volatility                     61.90%          
Exercise Price Ranging from 5.00 to 10.58                                
Stockholders Equity [Line Items]                                
Expected life of the stock option                   10 years            
Expected dividends                   0.00%            
Risk free interest rate, minimum                   0.28%            
Risk free rate maximum                   0.96%            
Exercise Price Ranging from 5.00 to 10.58 | Maximum                                
Stockholders Equity [Line Items]                                
Exercise price per share | $ / shares                   $ 10.58            
Expected volatility                   69.80%            
Exercise Price Ranging from 5.00 to 10.58 | Minimum                                
Stockholders Equity [Line Items]                                
Exercise price per share | $ / shares                   $ 5.00            
Expected volatility                   61.70%