Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Summary of Stock Option Activity (Detail)

v3.10.0.1
Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Number of shares, Outstanding, Beginning Balance 3,883,432    
Number of shares, Granted 295,443    
Number of shares, Exercised (461,200)    
Number of shares, Canceled (576,853)    
Number of shares, Outstanding, Ending Balance 3,140,822   3,883,432
Number of shares, Exercisable at September 30, 2018 1,314,939    
Weighted average exercise price per share, Granted $ 18.84    
Weighted average exercise price per share, Exercised 4.62    
Weighted average exercise price per share, Canceled 12.42    
Weighted average exercise price per share outstanding 10.14   $ 9.16
Weighted average exercise price per share Exercisable $ 7.01    
Aggregate intrinsic value, Exercised $ 6,416 $ 1,000  
Aggregate intrinsic value, Outstanding 17,718   $ 49,965
Aggregate intrinsic value, Exercisable $ 11,429    
Weighted average remaining contractual life, Outstanding 8 years 2 months 12 days   8 years 9 months 18 days
Weighted average remaining contractual life, Exercisable 7 years 8 months 12 days