Quarterly report pursuant to Section 13 or 15(d)

Borrowing Arrangements - Additional Information (Detail)

v3.10.0.1
Borrowing Arrangements - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 27, 2018
Apr. 30, 2016
Jun. 30, 2015
May 31, 2015
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Apr. 30, 2014
Debt Instrument [Line Items]                    
Amortization of debt discount and accretion related to debt             $ 219,000 $ 282,000    
Perceptive                    
Debt Instrument [Line Items]                    
Final fee due at the loan maturity date $ 3,400,000                  
Debt instrument, annual interest rate         13.30%   13.30%      
Credit Facility, interest expense         $ 170,000 $ 0 $ 398,000 0    
Amortization of debt discount and accretion related to debt         65,000   146,000      
Term Loan Facility | Perceptive                    
Debt Instrument [Line Items]                    
Maximum borrowing capacity under loan $ 10,000,000                  
Common stock exercise price $ 9.5792                  
Increase in applicable margin percentage on event of default 4.00%                  
Period for which interest only payments will be made 24 months                  
Credit Facility, principal payments $ 200,000                  
Credit Facility, maturity date Feb. 27, 2022                  
Exit fee $ 100,000                  
Number of shares issued for each warrant 190,000                  
Warrant exercisable period 7 years                  
Fair value of the warrant recorded as a debt discount $ 1,500,000                  
LIBOR | Term Loan Facility | Perceptive                    
Debt Instrument [Line Items]                    
Debt instrument, basis spread on variable rate 11.00%                  
SVB Growth Capital Loan                    
Debt Instrument [Line Items]                    
Maximum borrowing capacity under loan                   $ 6,000,000
Number of warrants to purchase shares of common stock   17,310 14,254             48,874
Final fee due at the loan maturity date                   $ 375,000
Amount drew down from bank   $ 3,000,000 $ 2,300,000 $ 800,000            
Common stock exercise price   $ 3.07 $ 3.07              
Aggregate amount drawn down from credit facility                 $ 6,000,000  
Debt instrument, frequency of periodic payment                 30  
Debt instrument first installment due date                 Nov. 01, 2016  
Debt instrument maturity date                 Apr. 30, 2019  
Debt instrument, annual interest rate                 5.44%  
Debt instrument principal paid during period             3,200,000 1,800,000    
Final fee paid             375,000      
Debt instrument interest paid during period             42,000 $ 187,000    
Total debt         $ 0   $ 0   $ 3,500,000  
SVB Growth Capital Loan | Prime Rate                    
Debt Instrument [Line Items]                    
Debt instrument, basis spread on variable rate                 1.19%  
Term Loan Drawn on Effective Date of Credit Facility | Term Loan Facility | Perceptive                    
Debt Instrument [Line Items]                    
Proceeds from initial term loan on closing date of Credit Facility $ 5,000,000                  
Additional Term Loan Drawn Six Months Following Effective Date of Credit Facility | Term Loan Facility | Perceptive                    
Debt Instrument [Line Items]                    
Remaining available amount from credit facility to be drawn six months following effective date of credit facility $ 5,000,000