Quarterly report pursuant to Section 13 or 15(d)

Borrowing Arrangements - Additional Information - (Detail)

v3.8.0.1
Borrowing Arrangements - Additional Information - (Detail)
1 Months Ended 9 Months Ended
Apr. 30, 2016
USD ($)
$ / shares
shares
Jun. 30, 2015
USD ($)
$ / shares
shares
May 31, 2015
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
Installment
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Apr. 30, 2015
USD ($)
$ / shares
shares
SVB | Amended Loan and Security Agreement              
Debt Instrument [Line Items]              
Final fee due at loan maturity date             $ 345,000
SVB | Second and Amended Loan and Security Agreement              
Debt Instrument [Line Items]              
Common stock exercise price | $ / shares $ 3.07 $ 3.07 $ 3.07        
Amount drew down from bank $ 3,000,000 $ 2,300,000 $ 800,000        
SVB | Second and Amended Loan and Security Agreement | Common Stock              
Debt Instrument [Line Items]              
Number of warrants to purchase shares of common stock | shares 17,310 17,310 17,310        
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%      
Growth Capital Advances | SVB | Amended Loan and Security Agreement              
Debt Instrument [Line Items]              
Maximum advance to be received based on corporate milestone             6,000,000
Debt instrument, frequency of periodic payment       3      
Growth Capital Loan              
Debt Instrument [Line Items]              
Debt instrument principal paid during period       $ 1,800,000 0    
Debt instrument interest paid during period       $ 187,000 $ 156,000    
Debt Instrument, covenant description       0 0    
Total debt       $ 4,145,000   $ 5,600,000  
Growth Capital Loan | SVB | Amended Loan and Security Agreement              
Debt Instrument [Line Items]              
Maximum borrowing capacity under loan             $ 6,000,000
Common stock exercise price | $ / shares             $ 3.07
Growth Capital Loan | SVB | Amended Loan and Security Agreement | Common Stock              
Debt Instrument [Line Items]              
Number of warrants to purchase shares of common stock | shares             34,620