Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Equity Offerings (Details)

v3.19.3
Stockholders' Equity - Equity Offerings (Details)
3 Months Ended 12 Months Ended
Jan. 29, 2019
USD ($)
Institution
$ / shares
shares
Jan. 28, 2019
USD ($)
$ / shares
shares
Dec. 14, 2015
USD ($)
Mar. 31, 2019
USD ($)
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2018
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
$ / shares
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  
Common stock, par value (in dollars per share) | $ / shares               $ 0.001 $ 0.001  
Offering price (in dollars per share) | $ / shares $ 1.00                  
Issuance of common stock, net of issuance costs       $ 8,896,000 $ 13,697,000 $ 10,344,000 $ 9,154,000      
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                
At-the-market sales facility - December 14, 2015 agreement                    
Stockholders' Equity                    
Offering amount                 $ 0  
Issuance of common stock (in shares) | shares               11,400,000    
Issuance of common stock, net of issuance costs               $ 20,000,000    
At-the-market sales facility - December 14, 2015 agreement | Maximum                    
Stockholders' Equity                    
Offering amount     $ 75,000,000              
Commission (as a percent)     3.00%              
At-the-market sales facility - December 14, 2015 agreement | Weighted-average                    
Stockholders' Equity                    
Offering price (in dollars per share) | $ / shares               $ 1.80    
At-the-market sales facility - June 2018 agreement                    
Stockholders' Equity                    
Offering amount           50,000,000     0  
Issuance of common stock (in shares) | shares               8,500,000    
Issuance of common stock, net of issuance costs               $ 13,200,000    
At-the-market sales facility - June 2018 agreement | Maximum                    
Stockholders' Equity                    
Offering amount           $ 175,000,000        
At-the-market sales facility - June 2018 agreement | Weighted-average                    
Stockholders' Equity                    
Offering price (in dollars per share) | $ / shares               $ 1.60    
At-the-market sales facility - April 17, 2019 agreement                    
Stockholders' Equity                    
Offering amount                   $ 50,000,000
At-the-market sales facility - April 17, 2019 agreement | Maximum                    
Stockholders' Equity                    
Offering amount                 $ 50,000,000  
Private Placement                    
Stockholders' Equity                    
Issuance of common stock (in shares) | shares 10,000,000                  
Issuance of common stock, net of issuance costs $ 9,200,000                  
Number of institutional investors | Institution 2