Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation - Summary of Stock-Based Compensation Expense, Net of Estimated Forfeitures (Detail)

v3.6.0.2
Stock Plans and Stock-Based Compensation - Summary of Stock-Based Compensation Expense, Net of Estimated Forfeitures (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense $ 2,473 $ 2,487
Research and Development [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 995 844
General and Administrative [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense $ 1,478 $ 1,643