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Shareholders' Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended
Apr. 30, 2016
Apr. 30, 2015
Feb. 23, 2015
May. 27, 2014
Equity, Class of Treasury Stock [Line Items]        
Common shares authorized for repurchase, shares     20,000,000 10,000,000
Remaining common shares authorized for repurchase, shares 6,995,059      
Stock repurchased and retired during period, common shares 324,700 401,977    
Stock repurchased and retired during period, total cost $ 10,704 $ 17,306    
Additional paid-in-capital reduction related to shares repurchased 0      
Retained earnings reduction related to shares repurchased $ (2,322)      
Employee Stock        
Equity, Class of Treasury Stock [Line Items]        
Stock repurchased and retired during period, common shares 0 180,776    
Stock repurchased and retired during period, total cost   $ 7,976