Annual report pursuant to Section 13 and 15(d)

Stock Plans - Schedule of Stock-based Compensation Expense (Detail)

v3.19.1
Stock Plans - Schedule of Stock-based Compensation Expense (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense $ 15,493 $ 16,089
Restricted Stock Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 427 327
Restricted Stock Awards [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 463 891
Common Stock Awards [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense   375
Stock Options [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 10,050 14,391
Performance-Based Stock Options under the 2018 Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 3,799  
Employee Stock Purchase Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 754 105
Sales and Marketing [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 1,018 438
Research and Development [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense 2,278 464
General and Administrative [Member]    
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]    
Stock-based compensation expense $ 12,197 $ 15,187