Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail)

v3.5.0.2
Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation $ 919 $ 712 $ 1,387 $ 1,228
Research and development [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation 462 317 684 569
General and administrative [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation $ 457 $ 395 $ 703 $ 659