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Capital Stock - Additional Information (Detail) - USD ($)
 3 Months Ended 23 Months Ended
Mar. 30, 2018
May 31, 2017
May 31, 2016
Apr. 30, 2018
Apr. 30, 2017
Apr. 30, 2018
Jan. 31, 2018
Class Of Stock [Line Items]              
Preference shares, shares authorized       20,000,000   20,000,000 20,000,000
Preference shares, par value       $ 0.00045   $ 0.00045 $ 0.00045
Preference shares, shares issued       0   0 0
Preference shares, shares outstanding       0   0 0
Ordinary shares, shares authorized       200,000,000   200,000,000 200,000,000
Stock repurchase program, period   12 months          
Stock repurchase program, commencing date   Jul. 01, 2017          
Stock repurchased during period, shares       437,448   1,937,332  
Stock repurchased during period, cash       $ 20,624,000 $ 8,773,000 $ 95,600,000  
Amount available under stock repurchase program       $ 11,100,000   $ 11,100,000  
2012 Equity Incentive Plan [Member]              
Class Of Stock [Line Items]              
Additional ordinary shares reserved for issuance 1,507,032            
2012 Equity Incentive Plan [Member] | Scenario, plan automatically increased by the lessor of [Member]              
Class Of Stock [Line Items]              
Annual increase in ordinary shares for available for future issuance 3,500,000            
Annual shares increase for future issuance by percentage under 2012 equity incentive plan 4.50%            
Amended and Restated 2012 Employee Stock Purchase Plan [Member]              
Class Of Stock [Line Items]              
Additional ordinary shares reserved for issuance 418,620            
Amended and Restated 2012 Employee Stock Purchase Plan [Member] | Scenario, plan automatically increased by the lessor of [Member]              
Class Of Stock [Line Items]              
Annual increase in ordinary shares for available for future issuance 1,500,000            
Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan 1.25%            
Stock Repurchase Program $75.0 Million Authorization [Member]              
Class Of Stock [Line Items]              
Stock repurchase program, authorization date     May 31, 2016        
Stock repurchase program, expiration date     Jun. 30, 2017        
Stock Repurchase Program $75.0 Million Authorization [Member] | Maximum [Member]              
Class Of Stock [Line Items]              
Amount authorized under stock repurchase program     $ 75,000,000        
Stock Repurchase Program $50.0 Million Authorization [Member]              
Class Of Stock [Line Items]              
Stock repurchase program, authorization date   May 31, 2017          
Stock repurchase program, expiration date   Jun. 30, 2018          
Stock Repurchase Program $50.0 Million Authorization [Member] | Maximum [Member]              
Class Of Stock [Line Items]              
Amount authorized under stock repurchase program   $ 50,000,000