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 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation $ (134) $ 712 $ 1,253 $ 1,940
Research and development [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation (70) 351 614 920
General and administrative [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total stock-based compensation $ (64) $ 361 $ 639 $ 1,020