Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.8.0.1
Stockholders' Equity - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Aug. 31, 2017
May 31, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2013
Jul. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Net proceeds from the issuance of common stock   $ 30,600,000     $ 30,609,789 $ 11,781,626    
Payment for repurchase of common stock         $ 11,202,542 0    
Warrants exercisable, outstanding     149,704   149,704      
Stock options granted to purchase common stock         1,702,600      
Stock-based compensation     $ 1,000,000 $ 700,000 $ 3,049,181 $ 2,456,196    
Employment Inducement Award [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Stock options granted to purchase common stock 525,000              
Stock options vesting period 4 years              
Stock options vesting rights, description         The stock options will vest over a four-year period, with a quarter of the options vesting on the first anniversary of the date of grant and the remainder of the options vesting monthly over the subsequent three years.      
2013 Warrants [Member] | Convertible promissory notes [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Warrant expiration date         May 30, 2018      
2013 Warrants [Member] | Series B Preferred Stock [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Warrant exercisable to purchase shares             1,124,026  
2013 Warrants [Member] | Series B Preferred Stock [Member] | Convertible promissory notes [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Exercise price of warrant per share             $ 0.90  
Lender Warrants [Member] | Series B convertible preferred stock [Member] | Term Loan One                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Exercise price of warrant per share             $ 0.90  
Warrant issued             111,112  
Warrant expiration date         Jul. 03, 2023      
Common Stock [Member] | 2013 Warrants [Member] | Convertible promissory notes [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Exercise price of warrant per share               $ 7.43
Common Stock [Member] | Lender Warrants [Member] | Convertible promissory notes [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Exercise price of warrant per share               $ 7.43
Warrants exercisable, outstanding               13,468
Common Stock [Member] | Stock Purchase Agreement with Advent [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Payment for repurchase of common stock   $ 11,200,000            
Shares repurchased and retired under stock purchase agreement   2,166,836            
Shares repurchased and retired price per share   $ 5.17            
Follow on Offering [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Common stock, shares issued   5,980,000            
Common stock, price per share   $ 5.50            
Post IPO [Member] | Common Stock [Member] | 2013 Warrants [Member] | Convertible promissory notes [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Warrants exercisable, outstanding               136,236