Annual report pursuant to Section 13 and 15(d)

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

v3.8.0.1
Stock-Based Compensation - Summary of Stock-based Compensation Expense (Detail) - Omnibus Plan [Member]
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense $ 11,720
Selling, General and Administrative [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense 5,988
Research and Development [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense 5,732
Employee Stock Options [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense 4,761
Employee Restricted Stock Units [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense 1,775
Nonemployee Stock Options [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense 4,530
Nonemployee Restricted Stock Units [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]  
Stock-based compensation expense $ 654