Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Narrative (Details)

v3.20.1
Stockholders' Equity - Narrative (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Aug. 09, 2019
USD ($)
Jan. 30, 2019
shares
Nov. 30, 2019
USD ($)
$ / shares
shares
Jun. 30, 2016
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
$ / shares
shares
Jun. 30, 2019
$ / shares
shares
Jan. 31, 2019
shares
Class of Stock [Line Items]                
Issuance of common stock resulting from exercise of stock options (shares)         279,075 596,269    
Cash proceeds from option exercises | $         $ 553 $ 986    
Number of shares called by warrants (shares)         123,238 156,888    
Cash proceeds from exercise of warrants | $         $ 246 $ 314    
Preferred stock, shares authorized (shares)         10,000,000 10,000,000    
Number of shares per unit (shares)       1        
Warrant exercise period       5 years        
Par value of preferred stock (USD per share) | $ / shares         $ 0.001 $ 0.001    
Par value of common stock (USD per share) | $ / shares         $ 0.001 $ 0.001    
Gross sales proceeds from common stock | $ $ 50,000              
Series A Convertible Preferred Stock                
Class of Stock [Line Items]                
Price per unit issued (USD per share) | $ / shares       $ 2.015        
Number of shares per unit (shares)       1        
Shares issued upon conversion of convertible preferred stock (shares)       1,000        
Proportion of beneficial ownership (as a percent)       9.99%        
Par value of preferred stock (USD per share) | $ / shares       $ 0.001        
Shares of preferred stock issued (shares)         2,907 2,907    
Series B Convertible Preferred Stock                
Class of Stock [Line Items]                
Shares of preferred stock issued (shares)         5,000 0    
Series C Convertible Preferred Stock                
Class of Stock [Line Items]                
Shares of preferred stock issued (shares)         3,522 0    
Tranche A Warrants                
Class of Stock [Line Items]                
Number of shares called by warrants (shares)       0.4        
Number of warrants       1        
Exercise price (USD per share) | $ / shares       $ 2.00        
Tranche B Warrants                
Class of Stock [Line Items]                
Number of shares called by warrants (shares)       0.2        
Number of warrants       1        
Exercise price (USD per share) | $ / shares       $ 3.00        
Common Stock                
Class of Stock [Line Items]                
Issuance of common stock resulting from exercise convertible securities (shares)         52,833      
Number of shares called by warrants (shares)         127,065      
Warrants                
Class of Stock [Line Items]                
Issuance of common stock resulting from exercise convertible securities (shares)         176,071      
Common Shares                
Class of Stock [Line Items]                
Issuance of common stock resulting from exercise of stock options (shares)         279,000 596,000    
Issuance of common stock resulting from exercise convertible securities (shares)         176,000 157,000    
Preferred Shares | Series B Convertible Preferred Stock                
Class of Stock [Line Items]                
Preferred stock, shares authorized (shares)               5,000
Common stock ownership limit (as a percent)             9.99%  
Beneficial ownership limitation (as a percent)             19.99%  
Effective period of change to beneficial ownership limitation         61 days      
Shares issued upon conversion of convertible preferred stock (shares)             1,000  
Par value of preferred stock (USD per share) | $ / shares             $ 0.001  
Preferred Shares | Series C Convertible Preferred Stock                
Class of Stock [Line Items]                
Common stock ownership limit (as a percent)     9.99%          
Shares issued upon conversion of convertible preferred stock (shares)     1,000          
Private Placement                
Class of Stock [Line Items]                
Shares of common stock issued (shares)     9,015,000          
Issue price per share (USD per share) | $ / shares     $ 3.55          
Net proceeds from underwritten public offering | $     $ 31,000          
Number of shares per unit (shares)     1          
Exercise price (USD per share) | $ / shares     $ 7.10          
Warrant exercise period     5 years          
Shares of stock sold, gross consideration | $     $ 32,000          
Number of warrants included with each unit (in shares)     1          
Private Placement | Series C Convertible Preferred Stock                
Class of Stock [Line Items]                
Shares issued upon conversion of convertible preferred stock (shares)     0.001          
Securities Purchase Agreement                
Class of Stock [Line Items]                
Number of capital units sold in private placement transaction (units)       8,188,804        
Price per unit issued (USD per share) | $ / shares       $ 2.015        
Gross proceeds from private placement units sold | $       $ 16,500        
Net proceeds from private placement units sold | $       $ 15,300        
2016 PIPE                
Class of Stock [Line Items]                
Shares of common stock issued (shares)       3,225,804        
Stock Exchange, Shares from Existing Shareholders | Common Shares                
Class of Stock [Line Items]                
Shares of common stock issued (shares)   5,000,000            
Preferred Share Exchange                
Class of Stock [Line Items]                
Issue price per share (USD per share) | $ / shares         $ 3.43      
Beneficial conversion feature | $         $ 2,800      
Preferred Share Exchange | Preferred Shares                
Class of Stock [Line Items]                
Shares of common stock issued (shares)   5,000            
2016 PIPE | Private Placement | Series A Convertible Preferred Stock                
Class of Stock [Line Items]                
Shares of preferred stock issued (shares)       4,963