Quarterly report pursuant to Section 13 or 15(d)

Equity - Narrative (Details)

v3.19.3
Equity - Narrative (Details)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Jul. 23, 2019
USD ($)
Jul. 08, 2019
shares
Oct. 04, 2018
USD ($)
shares
Jul. 29, 2017
technology
$ / shares
shares
Apr. 30, 2019
USD ($)
$ / shares
shares
Mar. 31, 2019
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
$ / shares
shares
Apr. 30, 2018
$ / shares
shares
Feb. 28, 2018
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
May 31, 2016
$ / shares
shares
Sep. 30, 2019
USD ($)
shares
Jun. 30, 2019
USD ($)
shares
Mar. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
shares
Sep. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
shares
Sep. 30, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
shares
Aug. 08, 2019
$ / shares
Mar. 29, 2019
$ / shares
Class of Stock                                          
Shares authorized (in shares)                       105,000,000           105,000,000      
Preferred stock authorized (in shares)                       5,000,000     5,000,000     5,000,000 5,000,000    
Common stock authorized (in shares)                       100,000,000     75,000,000     100,000,000 75,000,000    
Preferred stock, shares issued (in shares)                       0     0     0 0    
Maximum amount of shares to be sold in transaction | $     $ 20,000,000.0                                    
Shares of common stock issued | $                                 $ 5,122,000        
Shares granted (in shares)                                   1,115,000      
Shares granted, aggregate fair value | $                       $ 1,200,000           $ 1,200,000      
Exercise price (in dollars per share) | $ / shares                                   $ 1.30      
Shares granted, contractual term                                   8 years 7 months 9 days 9 years 5 months 4 days    
Unrecognized compensation cost, net of estimated forfeitures, related to the Company's non-vested equity awards | $                       $ 3,200,000           $ 3,200,000      
Weighted average period of expected recognition of compensation cost (in years)                                   2 years 6 months 3 days      
Period of agreement       12 months                                  
Proceeds from issuance or sale of equity | $             $ 2,300,000                            
2015 Stock Plan                                          
Class of Stock                                          
Total number of underlying shares of common stock available under 2015 Stock Plan (shares)                       4,500,000           4,500,000      
Restricted Stock Units (RSUs)                                          
Class of Stock                                          
Weighted average period of expected recognition of compensation cost (in years)                                   3 years 9 months 18 days      
Shares of equity investments granted in period other than options (shares)                                   316,907      
Vesting period (in years)                                   4 years      
Weighted average grant date fair value for equity investments granted other than options (usd per share) | $ / shares                                   $ 1.31      
Weighted average period of expected recognition of compensation cost for equity investments other than options (in years) | $                       $ 400,000           $ 400,000      
Common Stock                                          
Class of Stock                                          
Shares of common stock issued (in shares)                                 4,290,000        
Shares of common stock issued | $                                 $ 5,000        
Common Stock | Warrant                                          
Class of Stock                                          
Shares of equity investments granted in period other than options (shares)                     107,802                    
Exercised price per warrant (usd per share) | $ / shares                     $ 7.50                    
Warrant term                     5 years                    
The Warrants                                          
Class of Stock                                          
Number of warrants issued | technology       2                                  
Class of warrants, aggregate amounts (in shares)   150,000                                      
Exercised price per warrant (usd per share) | $ / shares                                       $ 1.64  
Vesting period       12 months                                  
Expiration period       5 years                                  
Stock compensation expense | $                       $ 100,000       $ 40,000.00   100,000      
Warrant term   3 years                                      
Consulting fees | $                                   $ 20,000      
GSK Consulting Agreement Warrant One                                          
Class of Stock                                          
Class of warrants, aggregate amounts (in shares)       100,000                                  
Exercised price per warrant (usd per share) | $ / shares       $ 2.41                                  
GSK Consulting Agreement Warrant Two                                          
Class of Stock                                          
Class of warrants, aggregate amounts (in shares)       50,000                                  
Exercised price per warrant (usd per share) | $ / shares       $ 3.00                                  
Consulting Agreement Warrant Three                                          
Class of Stock                                          
Class of warrants, aggregate amounts (in shares)               100,000                          
Exercised price per warrant (usd per share) | $ / shares               $ 3.00                          
Warrant term               3 years                          
Lincoln Park                                          
Class of Stock                                          
Shares of common stock issued (in shares)     243,013                 100,674 0 605,367 1,399,153            
Shares of common stock issued | $                       $ 52,000   $ 883,000              
Lincoln Park | Common Stock                                          
Class of Stock                                          
Shares of common stock issued (in shares)                       100,674   605,367              
Lincoln Park | Commitment Shares                                          
Class of Stock                                          
Maximum amount of shares to be sold in transaction | $     $ 20,000,000.0                                    
Shares of common stock issued (in shares)     121,507                 674 0 5,367 10,918            
Shares of common stock issued | $     $ 337,788                 $ 100,000   $ 900,000 $ 1,800,000            
At Market Issuance Sales Agreement                                          
Class of Stock                                          
Commissions paid, percentage of gross proceeds (percent)                   3.00%                      
At Market Issuance Sales Agreement | Roth Capital Partners and National Securities Corporation | Maximum | Common Stock                                          
Class of Stock                                          
Aggregate sales price | $                   $ 13,000,000                      
At Market Issuance Sales Agreement | Oppenheimer & Co. Inc. | Common Stock                                          
Class of Stock                                          
Aggregate sales price | $ $ 15,000,000                                        
Commissions paid, percentage of gross proceeds (percent) 3.00%                                        
Securities Purchase Agreement                                          
Class of Stock                                          
Exercised price per warrant (usd per share) | $ / shares                 $ 2.80                        
Warrant term                 5 years                        
Number of units sold (in shares)                 4,290,000                        
Proceeds from issuance or sale of equity | $                 $ 9,000,000.0                        
Net proceeds from registered offering | $                 $ 8,200,000                        
Warrants, initial exercise period                 6 months                        
Securities Purchase Agreement | Common Stock                                          
Class of Stock                                          
Class of warrants, aggregate amounts (in shares)                 2,145,000                        
Sale of common stock (in dollars per share) | $ / shares                 $ 2.10                        
June 2018 Registered Direct Offering                                          
Class of Stock                                          
Exercised price per warrant (usd per share) | $ / shares             $ 2.02                            
Expiration period             5 years                            
Number of units sold (in shares)             1,092,636                            
Sale of common stock (in dollars per share) | $ / shares             $ 2.105                            
Warrants, initial exercise period             6 months                            
Common stock offered for each warrant (in shares)             0.65                            
March 2019 Registered Direct Offerings                                          
Class of Stock                                          
Exercised price per warrant (usd per share) | $ / shares           $ 1.10               $ 1.10              
Warrant term           5 years                              
Proceeds from issuance or sale of equity | $           $ 5,250,000                              
Net proceeds from registered offering | $           $ 4,700,000                              
Units sold in period (in units)           5,250,000                              
Common stock offered for each warrant (in shares)           0.5               0.5              
Unit offering (in dollars per unit) | $ / shares           $ 1.00               $ 1.00              
March 2019 Registered Direct Offerings | Common Stock                                          
Class of Stock                                          
Exercised price per warrant (usd per share) | $ / shares                                         $ 1.10
Number of units sold (in shares)           1                              
March 2019 Registered Direct Offerings | Underwriter                                          
Class of Stock                                          
Unit offering (in dollars per unit) | $ / shares           $ 0.93               $ 0.93              
April Offerings                                          
Class of Stock                                          
Shares of common stock issued | $                         $ 3,584,000                
Exercised price per warrant (usd per share) | $ / shares         $ 1.75                                
Warrant term         5 years                                
Number of units sold (in shares)         9,375,000                                
Proceeds from issuance or sale of equity | $         $ 15,000,000                                
Net proceeds from registered offering | $         $ 13,700,000                                
Common stock offered for each warrant (in shares)         0.5                                
Unit offering (in dollars per unit) | $ / shares         $ 1.60                                
April Offerings | Common Stock                                          
Class of Stock                                          
Shares of common stock issued (in shares)                         9,375,000                
Shares of common stock issued | $                         $ 9,000                
Number of units sold (in shares)         1