Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Additional Information (Details)

v3.10.0.1
Long-Term Debt - Additional Information (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Dec. 31, 2016
Sep. 30, 2018
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Debt Instrument [Line Items]          
Long-term debt, net   $ 5,532,000 $ 5,532,000    
Accretion of final payment fee of debt     64,000 $ 72,000  
Success fee $ 250,000        
Current share price (in dollars per share) $ 8.00        
Contingent success fee liability   33,000 33,000    
Debt covenant, unrestricted cash   6,380,000 6,380,000    
Cash $ 16,846,000 $ 12,995,000 $ 12,995,000 $ 33,439,000 $ 27,813,000
Effective interest rate percentage   10.11% 9.92%    
Loan Agreement          
Debt Instrument [Line Items]          
Maximum borrowing capacity $ 7,000,000        
Debt term     36 months    
Long-term debt, net   $ 245,000 $ 245,000    
Accretion of final payment fee of debt     $ 161,000    
LIBOR | Loan Agreement          
Debt Instrument [Line Items]          
Variable rate percentage 5.41%