Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
9 Months Ended
Dec. 31, 2016
Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]    
Number of shares, Outstanding, Beginning Balance   1,930,600
Number of shares, Granted   2,120,347
Number of shares, Exercised   (43,130)
Number of shares, Canceled   (20,825)
Number of shares, Outstanding, Ending Balance 1,930,600 3,986,992
Number of shares, Exercisable at September 30, 2017   1,193,700
Weighted average exercise price per share, Granted   $ 13.29
Weighted average exercise price per share, Exercised   4.14
Weighted average exercise price per share, Canceled   5.85
Weighted average exercise price per share outstanding $ 4.45 9.15
Weighted average exercise price per share Exercisable   $ 5.21
Aggregate intrinsic value, Outstanding   $ 61,172
Aggregate intrinsic value, Exercisable   $ 23,010
Weighted average remaining contractual life, Outstanding 9 years 1 month 6 days 9 years 1 month 6 days
Weighted average remaining contractual life, Exercisable   8 years 3 months 19 days