Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
Stock-based Compensation - Expense Related to Stock Options (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock-based compensation expense related to stock options $ 446 $ 468 $ 938 $ 893
Research and development        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock-based compensation expense related to stock options 165 129 323 237
Selling, general and administrative        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock-based compensation expense related to stock options $ 281 $ 339 $ 615 $ 656