Quarterly report pursuant to Section 13 or 15(d)

Capitalization and Equity Structure - Additional Information (Details)

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Capitalization and Equity Structure - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 2 Months Ended 3 Months Ended
Oct. 29, 2020
Jun. 30, 2020
Dec. 31, 2019
May 30, 2019
Feb. 28, 2021
Mar. 31, 2022
Mar. 31, 2021
Dec. 31, 2021
May 31, 2019
Class of Stock [Line Items]                  
Common stock, shares authorized (in shares)           141,429,000   141,429,000  
Preferred Stock, shares authorized (in shares)           10,000,000   10,000,000  
Common stock, shares outstanding (in shares)           12,844,000   12,693,000  
Common stock, shares issued (in shares)           12,844,000   12,693,000  
Preferred stock, shares issued (in shares)           0   0  
Preferred stock, shares outstanding (in shares)           0   0  
Proceeds from direct offering           $ 0 $ 37,295    
Number warrants called (in shares)           1,240,000   1,240,000  
Value of shares sold           $ 0 $ 1,417    
Warrants issued (in shares)           0      
Common stock                  
Class of Stock [Line Items]                  
Warrants exercised (in shares)           0 358,000    
Exercise of warrants (in shares)             300,000    
At-the-market offering                  
Class of Stock [Line Items]                  
Number warrants called (in shares)           0      
Sale of shares (in dollars per share) $ 6.75                
Value of shares sold $ 7,500                
At-the-market offering | Common stock                  
Class of Stock [Line Items]                  
Available for future offerings           $ 6,668      
February 2021 Offering                  
Class of Stock [Line Items]                  
Percentage of warrants issued to purchase shares of common stock         7.00%        
Exercise price (in dollars per share)         $ 12.81        
February 2021 Offering | Underwriting agreement                  
Class of Stock [Line Items]                  
Number warrants called (in shares)         3,902,000        
Sale of shares (in dollars per share)         $ 10.25        
Value of shares sold         $ 40,000        
Proceeds from direct offering         $ 36,504        
Expected term         5 years        
2021 Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)         273,000 273,000      
Exercise price (in dollars per share)         $ 12.81 $ 12.81      
Warrants issued (in shares)         273,000 0      
Class of warrant or right expiration period         5 years 5 years      
Duration of put option         30 days        
Put option pay period         5 days        
June 2020 Investor Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)   874,000       127,000   127,000  
Exercise price (in dollars per share)   $ 5.18       $ 5.18      
Warrants exercised (in shares)           0 270    
Warrants issued (in shares)           0      
Class of warrant or right expiration period           5 years 6 months      
Duration of put option   30 days              
June 2020 Placement Agent Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)           39,000   39,000  
Exercise price (in dollars per share)   $ 5.64              
Warrants exercised (in shares)           0 83    
Warrants issued (in shares)   122,000       0      
Class of warrant or right expiration period           5 years      
December 2019 Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)     556,000     556,000   556,000  
Exercise price (in dollars per share)     $ 8.10     $ 8.10      
Warrants issued (in shares)           0      
Class of warrant or right expiration period     5 years     5 years      
Duration of put option     30 days            
Put option pay period     5 days            
December 2019 Placement Agent Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)     52,000     52,000   52,000  
Exercise price (in dollars per share)     $ 8.44     $ 8.44      
Warrants issued (in shares)           0      
Class of warrant or right expiration period           5 years      
May 2019 Warrants                  
Class of Stock [Line Items]                  
Number warrants called (in shares)           193,000   193,000 444,000
Exercise price (in dollars per share)   $ 3.52       $ 3.52     $ 3.52
Warrants exercised (in shares)           0 5    
Warrants issued (in shares)           0      
Class of warrant or right expiration period           5 years      
Duration of put option       90 days          
May 2019 Warrants | Direct offering | Common stock                  
Class of Stock [Line Items]                  
Sale of shares (in dollars per share)   4.51              
June 2020 Warrants                  
Class of Stock [Line Items]                  
Exercise price (in dollars per share)   $ 5.18              
Class of warrant or right expiration period           5 years 6 months