Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.5.0.2
Equity - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock option outstanding 5,437,280   5,437,280   5,326,505
Stock options, granted     2,372,527    
Unrecognized stock-based compensation cost $ 7,400,000   $ 7,400,000    
Unrecognized share-based compensation expense, weighted-average recognition period     1 year 4 months 24 days    
Stock compensation expense (gain) 1,560,000 $ 508,000 $ 2,348,000 $ 813,000  
Research And Development Expense [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock compensation expense (gain) 372,000 123,000 363,000 178,000  
Research And Development Expense [Member] | Warrant [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock compensation expense (gain) $ 74,000 $ 111,000 $ (10,000) $ 207,000  
Non-Employees [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock options, granted     1,375,000    
Stock option vested     485,000    
Stock option unvested 890,000   890,000    
Unrecognized stock-based compensation cost $ 2,400,000   $ 2,400,000