Quarterly report pursuant to Section 13 or 15(d)

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

v3.4.0.3
Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Total stock-based compensation $ 468 $ 516
Research and development [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Total stock-based compensation 222 252
General and administrative [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Total stock-based compensation $ 246 $ 264