Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Equity Offerings (Details)

v3.21.2
Stockholders' Equity - Equity Offerings (Details)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Jan. 28, 2019
USD ($)
$ / shares
shares
Aug. 31, 2020
USD ($)
$ / shares
shares
Jan. 31, 2019
USD ($)
Institution
$ / shares
shares
Sep. 30, 2021
USD ($)
shares
Jun. 30, 2021
USD ($)
Mar. 31, 2021
USD ($)
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Sep. 30, 2021
USD ($)
shares
Sep. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
shares
Apr. 30, 2019
USD ($)
Stockholders' Equity                          
Common stock authorized (in shares) | shares       200,000,000           200,000,000   200,000,000  
Preferred stock authorized (in shares) | shares       5,000,000           5,000,000   5,000,000  
Net proceeds from the offering                   $ 7,948,000 $ 96,233,000    
Issuance of common stock, net of issuance costs         $ 5,156,000 $ 2,792,000 $ 60,644,000 $ 32,029,000 $ 3,551,000        
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 | Wainwright | Maximum                          
Stockholders' Equity                          
Offering amount                         $ 50,000,000.0
At-the-market sales facility - December 31, 2020 agreement | Wainwright                          
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                      
HCW ATM Program                          
Stockholders' Equity                          
Net proceeds from the offering       $ 0                  
Stock available for further issuance       $ 41,900,000           $ 41,900,000