Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Summary of Stock-based Compensation Expense (Detail)

v3.10.0.1
Stock-Based Compensation - Summary of Stock-based Compensation Expense (Detail) - Omnibus Plan [Member] - 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, Compensation Cost [Line Items]        
Stock-based compensation expense $ 685 $ 9,191 $ 2,909 $ 9,634
Selling, General and Administrative [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense 695 4,539 2,031 4,961
Research and Development [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense (10) 4,652 878 4,673
Employee Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense 150 3,891 726 3,891
Employee Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense (26) 706 794 1,141
Nonemployee Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense (132) 4,209 293 4,209
Nonemployee Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Stock-based compensation expense $ 693 $ 385 $ 1,096 $ 393