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Stock-Based Compensation - Stock Option Assumptions (Detail) (USD $)
3 Months Ended
Oct. 31, 2013
Oct. 31, 2012
Service Based Option [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term 5 years 11 months 1 day 5 years 11 months 9 days
Expected volatility 37.41% 38.73%
Expected dividend yield 2.36% 2.20%
Risk-free interest rate 1.78% 0.89%
Weighted-average market value of underlying stock at grant date (USD per share) $ 31.07 $ 30.21
Weighted average exercise price (USD per share) $ 31.07 $ 30.21
Weighted-average fair value of options granted during the period (USD per share) $ 9.18 $ 8.96
Vesting period of service based stock options 33.33%  
Performance Based Options [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expiration period of options 10 years  
Service Based Option [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expiration period of options 10 years  
Service Based Option [Member] | Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years  
Restricted Stock [Member] | Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 7 years  
Restricted Stock [Member] | Minimum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 5 years  
Cliff-Vested Restricted Shares [Member] | Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years