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Stock-Based Compensation - Stock Option Assumptions (Detail) - $ / shares
6 Months Ended
Jan. 31, 2019
Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term 6 years 2 months 12 days 6 years 27 days
Expected volatility 25.83% 26.52%
Expected dividend yield 2.71% 2.72%
Risk-free interest rate 3.01% 1.96%
Weighted-average market value of underlying stock at grant date $ 43.96 $ 36.85
Options, Grants in Period, Weighted Average Exercise Price 43.96 36.85
Weighted-average fair value of options granted during the period $ 9.70 $ 7.96