Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Summary of Activity of Restricted Stock Units (Detail)

v3.8.0.1
Stock-Based Compensation - Summary of Activity of Restricted Stock Units (Detail) - Restricted Stock Units [Member] - $ / shares
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of restricted stock units outstanding, Unvested beginning balance 1,373,933  
Number of restricted stock units outstanding, Granted 26,625 0
Number of restricted stock units outstanding, Cancelled (102,900)  
Number of restricted stock units outstanding, Unvested ending balance 1,297,658  
Weighted-average grant date fair value, Unvested beginning balance $ 8.00  
Weighted-average grant date fair value, Granted 23.39  
Weighted-average grant date fair value, Cancelled 8.00  
Weighted-average grant date fair value, Unvested ending balance $ 8.32