Annual report pursuant to Section 13 and 15(d)

Borrowing Arrangements - Additional Information - (Detail)

v3.8.0.1
Borrowing Arrangements - Additional Information - (Detail)
1 Months Ended 12 Months Ended
Apr. 30, 2016
USD ($)
$ / shares
shares
Jun. 30, 2015
USD ($)
$ / shares
shares
May 31, 2015
USD ($)
Dec. 31, 2017
USD ($)
Installment
Dec. 31, 2016
USD ($)
$ / shares
Aug. 01, 2017
$ / shares
Dec. 31, 2015
$ / shares
Apr. 30, 2015
USD ($)
shares
Dec. 31, 2014
$ / shares
Debt Instrument [Line Items]                  
Common stock exercise price | $ / shares         $ 3.07 $ 39.82 $ 3.07   $ 3.07
Growth Capital Loan                  
Debt Instrument [Line Items]                  
Debt instrument principal paid during period       $ 2,400,000 $ 237,000        
Debt instrument interest paid during period       $ 400,000 220,000        
Debt Instrument, covenant description       The Company does not have any financial loan covenants related to the Growth Capital Loan.          
Total debt       $ 3,545,000 $ 5,600,000        
SVB                  
Debt Instrument [Line Items]                  
Debt instrument, frequency of periodic payment       3          
Maximum borrowing capacity under loan               $ 6,000,000  
Number of warrants to purchase shares of common stock | shares 17,310 17,310           14,254  
Final fee due at loan maturity date               $ 345,000  
Amount drew down from bank $ 3,000,000 $ 2,300,000 $ 800,000            
Common stock exercise price | $ / shares $ 3.07 $ 3.07              
SVB | Loan and Security Agreement                  
Debt Instrument [Line Items]                  
Debt instrument, frequency of periodic payment       30          
Amount drew down from bank       $ 6,000,000          
Debt instrument first installment due date       Nov. 01, 2016          
Debt instrument maturity date       Apr. 30, 2019          
Interest accrual rate       5.44%          
Number of frequency of consecutive equal monthly payments of principal plus interest paid | Installment       30          
SVB | Loan and Security Agreement | Prime Rate                  
Debt Instrument [Line Items]                  
Debt instrument, basis spread on variable rate       1.19%