Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail)

v3.10.0.1
Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized stock-based compensation expense, expected recognition weighted-average period 3 years 7 months 6 days  
Restricted Stock Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Weighted-average grant date fair value, Granted $ 16.95 $ 8.00
Total fair value vested $ 1.7 $ 0.3
Unrecognized stock-based compensation expense related to restricted stock units $ 6.3  
Unrecognized stock-based compensation expense, expected recognition weighted-average period 4 years