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Capital Stock - Additional Information (Detail) - USD ($)
12 Months Ended
Nov. 29, 2016
May 31, 2016
Jan. 31, 2017
Jan. 31, 2016
Jan. 31, 2015
Class Of Stock [Line Items]          
Preference shares, shares authorized     20,000,000 20,000,000  
Preference shares, par value     $ 0.00045 $ 0.00045  
Preference shares, shares issued     0 0  
Preference shares, shares outstanding     0 0  
Ordinary shares, shares authorized     200,000,000 200,000,000  
Stock repurchase program, expiration date Jun. 30, 2017        
Stock repurchase program, period   6 months      
Stock repurchased during period, shares     405,089    
Stock repurchased during period, cash     $ 20,183,000 $ 0 $ 0
Maximum          
Class Of Stock [Line Items]          
Amount authorized under stock repurchase program   $ 75,000,000