Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Equity Offerings (Details)

v3.20.4
Stockholders' Equity - Equity Offerings (Details)
 1 Months Ended 12 Months Ended
Jan. 29, 2019
USD ($)
Institution
$ / shares
shares
Jan. 28, 2019
USD ($)
$ / shares
shares
Aug. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
shares
Dec. 31, 2019
USD ($)
shares
Apr. 17, 2019
USD ($)
Stockholders' Equity            
Common stock authorized (in shares) | shares       200,000,000 200,000,000  
Preferred stock authorized (in shares) | shares       5,000,000 5,000,000  
Proceeds from Issuance of Common Stock       $ 101,010,000 $ 10,312,000  
Issuance of common stock, net of issuance costs       $ 101,010,000 $ 9,965,000  
Wainwright            
Stockholders' Equity            
Percentage of aggregate gross proceeds paid   7.00%        
Expenses paid   $ 50,000        
Warrants to purchase shares of common stock | shares   500,000        
Warrants term   5 years        
Exercise price (in dollars per share) | $ / shares   $ 1.25        
Number of warrants exercised in a cashless exercise | shares       327,500    
Common shares issued in conversion of warrants | shares       201,925    
At-the-market sales facility - April 17, 2019 agreement | Maximum            
Stockholders' Equity            
Offering amount           $ 50,000,000.0
At-the-market sales facility - December 31, 2020 agreement            
Stockholders' Equity            
Offering amount       $ 50,000,000.0    
Private Placement            
Stockholders' Equity            
Issuance of common stock (in shares) | shares 10,000,000          
Offering price (in dollars per share) | $ / shares $ 1.00          
Issuance of common stock, net of issuance costs $ 9,200,000          
Number of institutional investors | Institution 2          
Public Offering            
Stockholders' Equity            
Issuance of common stock (in shares) | shares     25,000,000      
Offering price (in dollars per share) | $ / shares     $ 2.30      
Issuance of common stock, net of issuance costs     $ 53,700,000      
Time period for full exercise of option to purchase additional shares     30 days      
CW ATM Program            
Stockholders' Equity            
Issuance of common stock (in shares) | shares       39,300,000    
Proceeds from Issuance of Common Stock       $ 47,300,000    
Stock available for further issuance       $ 50,000,000.0