Quarterly report pursuant to Section 13 or 15(d)

Stock Plan and Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail)

v3.19.3
Stock Plan and Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense $ 2,865 $ 1,728 $ 7,483 $ 5,275
Research and Development [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense 1,504 741 3,602 2,045
General and Administrative [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense $ 1,361 $ 987 $ 3,881 $ 3,230