Quarterly report pursuant to Section 13 or 15(d)

Stock Plans - Additional Information (Detail)

v3.8.0.1
Stock Plans - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended
Jan. 31, 2018
Mar. 31, 2018
Dec. 31, 2017
Class of Stock [Line Items]      
Accrued employee contributions   $ 1,908 $ 3,117
2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]      
Class of Stock [Line Items]      
Unrecognized compensation expense related to stock options   23,339  
Employee Stock Purchase Plan [Member]      
Class of Stock [Line Items]      
Common stock granted 35,812    
Accrued employee contributions   213  
Restricted Stock [Member] | 2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]      
Class of Stock [Line Items]      
Unrecognized cost of share-based compensation awards   $ 742  
Cost of share-based compensation awards, recognition period   2 years 1 month 6 days  
Restricted Stock Units [Member] | 2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]      
Class of Stock [Line Items]      
Unrecognized cost of share-based compensation awards   $ 143  
Cost of share-based compensation awards, recognition period   4 months 24 days  
Stock Options [Member]      
Class of Stock [Line Items]      
Weighted Average Grant Date Fair Value, Granted   $ 7.91  
Aggregate intrinsic value of the options exercised   $ 692  
Total grant date fair value of stock options vested   $ 1,761  
Stock Options [Member] | 2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]      
Class of Stock [Line Items]      
Cost of share-based compensation awards, recognition period   2 years 8 months 12 days