Annual report pursuant to Section 13 and 15(d)

Common Stock - Summary of Share-Based Compensation Expense (Detail)

v3.3.1.900
Common Stock - Summary of Share-Based Compensation Expense (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation $ 2,328 $ 3,860 $ 2,834
Research and development [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation 1,111 1,893 1,296
General and administrative [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation $ 1,217 $ 1,967 $ 1,538