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 6 Months Ended
Oct. 29, 2020
Jun. 30, 2020
Dec. 31, 2019
May 30, 2019
Feb. 28, 2021
Jun. 30, 2022
Mar. 31, 2021
Jun. 30, 2022
Jun. 30, 2021
Dec. 31, 2021
Sep. 30, 2020
May 31, 2019
Class of Stock [Line Items]                        
Common stock, shares authorized (in shares)           141,429,000   141,429,000   141,429,000    
Preferred Stock, shares authorized (in shares)           10,000,000   10,000,000   10,000,000    
Common stock, shares outstanding (in shares)           13,010,000   13,010,000   12,693,000    
Common stock, shares issued (in shares)           13,010,000   13,010,000   12,693,000    
Preferred stock, shares issued (in shares)           0   0   0    
Preferred stock, shares outstanding (in shares)           0   0   0    
Proceeds from direct offering               $ 0 $ 37,295      
Number warrants called (in shares)           1,240,000   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   273,000        
Exercise price (in dollars per share)         $ 12.81 $ 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   127,000    
Exercise price (in dollars per share)           $ 5.18   $ 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   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   556,000    
Exercise price (in dollars per share)     $ 8.10     $ 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   52,000    
Exercise price (in dollars per share)     $ 8.44     $ 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   193,000   444,000
Exercise price (in dollars per share)           $ 3.52   $ 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