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Share-Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Jan. 31, 2018
Jan. 31, 2017
Jan. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Assumed annualized forfeiture rate   5.00% 5.00%
Tax benefit associated with share-based compensation expense $ 5,438 $ 7,132 $ 6,182
Tax benefit realized from share-based compensation $ 1,753 $ 2,272 $ 14,512
Common shares per PSU 100.00%    
2017 Stock Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common shares authorized 10,000,000    
Awards granted 0    
Two Thousand Eight Stock Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common shares authorized 10,000,000    
Common shares available to grant 3,903,823    
2017 and 2008 Stock Incentive Plan | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 7 years    
2017 and 2008 Stock Incentive Plan | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 10 years    
Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Awards granted 160,000    
Compensation cost of stock options granted but not yet vested $ 278    
Weighted average period of recognition (in years) 3 months 18 days    
Stock Options | Non-employee Directors      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 1 year    
Stock Options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 1 year    
Stock Options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 3 years    
Stock Appreciation Rights (SARs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Awards granted 0 0 0
Stock options vesting period, maximum (in years) 5 years    
Compensation cost of stock options granted but not yet vested $ 4    
Weighted average period of recognition (in years) 1 month 6 days    
Performance Stock Units (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation cost of stock options granted but not yet vested $ 11,249    
Weighted average period of recognition (in years) 1 year 10 months 24 days    
Weighted average grant date fair value $ 23.38 $ 27.30 $ 18.94
Granted, Shares 390,000    
Vested, Shares 200,000    
Aggregate grant date fair value, vested $ 29.58    
Performance Stock Units (PSUs) | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 3 years    
Performance Stock Units (PSUs) | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 5 years    
Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation cost of stock options granted but not yet vested $ 14,207    
Weighted average period of recognition (in years) 2 years 1 month 6 days    
Weighted average grant date fair value $ 26.01 $ 28.10  
Granted, Shares 621,500   0
Vested, Shares 0 0  
Aggregate grant date fair value, vested $ 0   $ 39.06
Restricted Stock Units (RSUs) | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 3 years    
Restricted Stock Units (RSUs) | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, maximum (in years) 5 years