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Stock-Based Compensation - Stock Option Assumptions (Detail) - $ / shares
3 Months Ended
Oct. 31, 2016
Oct. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]    
Expected term (in years) 6 years 1 month 9 days 6 years 1 month 12 days
Expected volatility 29.43% 28.59%
Expected dividend yield 2.70% 2.59%
Risk-free interest rate 1.26% 1.64%
Weighted-average market value of underlying stock at grant date $ 35.14 $ 19.97
Options, Grants in Period, Weighted Average Exercise Price 35.14 19.97
Weighted-average fair value of options granted during the period $ 7.56 $ 4.58