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Stock-Based Compensation - Stock Option Assumptions (Detail) - $ / shares
3 Months Ended
Oct. 31, 2015
Oct. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]    
Expected term (in years) 6 years 1 month 12 days 6 years 17 days
Expected volatility 28.59% 30.27%
Expected dividend yield 2.59% 2.48%
Risk-free interest rate 1.64% 1.91%
Weighted-average market value of underlying stock at grant date $ 19.97 $ 22.66
Weighted average exercise price 19.97 22.66
Weighted-average fair value of options granted during the period $ 4.58 $ 6.10