Annual report pursuant to Section 13 and 15(d)

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

v3.19.1
Stock-based Compensation - Expense Related to Stock Options (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense related to stock options $ 1,816 $ 1,662
Research and development, net    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense related to stock options 519 458
Selling, general and administrative    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense related to stock options $ 1,297 $ 1,204