Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation - Additional Information (Detail)

v3.6.0.2
Stock Plans and Stock-Based Compensation - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Jan. 01, 2017
Jul. 31, 2016
Sep. 30, 2013
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2013
Dec. 31, 2007
Apr. 30, 2014
Jan. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Fair value of options vested       $ 2,200,000 $ 2,200,000        
Share based compensation, stock option, unamortized expense       $ 3,500,000 $ 4,800,000        
Share based compensation, stock option, unamortized expense vesting period       1 year 9 months 18 days 2 years 7 months 6 days        
Number of option granted to employees       646,667,000 845,703,000        
Clinical development expense recognized       $ 199,000          
Share reserved for issue       5,123,651 3,951,819        
Allocated share-based compensation expense       $ 2,473,000 $ 2,487,000        
Options to purchase common stock       114,436          
Performance Option [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of option granted to employees       327,000,000          
Unrecognized stock based compensation       $ 192,000          
Scientific Advisors and Consultants [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, expiration period       10 years          
Share based compensation arrangement by share based payment award, award vesting period       60 months          
Allocated share-based compensation expense       $ 17,510 $ 21,265        
Options to purchase common stock       18,000 10,000        
Options to purchase common stock, unvested       28,410          
Incentive award issued       2,335          
Incentive awards outstanding, Unvested       584          
Executives and Senior Officers [Member] | Performance Option [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of option granted to employees   327,000              
2013 Equity Incentive Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, expiration period     10 years            
Share based compensation arrangement percentage increase in share reserved     5.00%            
Shares available for grant       496,120          
2013 Equity Incentive Plan [Member] | Subsequent Event [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Increased in shares available for issuance 1,172,350                
2013 Equity Incentive Plan [Member] | Incentive Stock Options for Employees and Directors [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, exercise price percentage     100.00%            
2013 Equity Incentive Plan [Member] | Nonqualified Options to Employees, Directors and Consultants [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, exercise price percentage     85.00%            
2013 Equity Incentive Plan [Member] | Restricted Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, exercise price percentage     85.00%            
Share based compensation arrangement by share based payment award, award vesting period     4 years            
2013 Equity Incentive Plan [Member] | Stock Options to 10% Stockholders [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, exercise price percentage             110.00%    
Share based compensation arrangement by share based payment award, award vesting period             5 years    
Incentive Awards [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share based compensation arrangement by share based payment award, expiration period           10 years      
Share reserved for issue           252,752   252,752 252,752
Exercisable weighted average price per share           $ 5.21   $ 5.21 $ 5.21
Stock option plan, Description       Vest monthly over four years effective from their grant date.          
Allocated share-based compensation expense       $ 272,000 $ 323,000        
Incentive Awards [Member] | First Tranche [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Incentive awards vested percentage           100.00%