Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Stock-Based Compensation Expense (Detail)

v3.7.0.1
Stock Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Amortization of stock-based compensation $ 505 $ 843
Research and Development    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Amortization of stock-based compensation 151 318
General and Administrative    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Amortization of stock-based compensation $ 354 $ 525