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Stock-Based Compensation - Stock Option Assumptions (Detail) - $ / shares
6 Months Ended
Jan. 31, 2016
Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term 6 years 1 month 10 days 6 years 17 days
Expected volatility 29.95% 34.03%
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 $ 20.02 $ 22.70
Options, Grants in Period, Weighted Average Exercise Price 20.02 22.70
Weighted-average fair value of options granted during the period $ 4.58 $ 6.11