Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Expense Related to Stock Options (Detail)

v3.10.0.1
Stock-based Compensation - Expense Related to Stock Options (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based compensation expense related to stock options $ 458 $ 407 $ 1,351 $ 1,241
Research and development        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based compensation expense related to stock options 134 120 371 334
Selling, general and administrative        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based compensation expense related to stock options $ 324 $ 287 $ 980 $ 907