Annual report pursuant to Section 13 and 15(d)

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

v3.8.0.1
Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized stock-based compensation expense, expected recognition weighted-average period 4 years 2 months 12 days    
Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average grant date fair value, Granted $ 8.00    
Number of restricted stock units granted 1,452,333 0 0
Total fair value vested $ 314    
Unrecognized stock-based compensation expense related to restricted stock units $ 7,000    
Unrecognized stock-based compensation expense, expected recognition weighted-average period 4 years 10 months 24 days