Stock-Based Compensation (Details) (USD $)	9 Months Ended
Apr. 30, 2012 Y	Apr. 30, 2011 Y
Performance Based Options [Member]
Stock Option Assumptions
Expected term (in years)	6.57	6.57
Expected volatility	39.21%	39.39%
Expected dividend yield	1.99%	1.96%
Risk-free interest rate	2.05%	2.35%
Weighted-average market value of underlying stock at grant date	$ 29.55	$ 28.43
Weighted average exercise price	$ 29.55	$ 28.35
Weighted-average fair value of options granted during the period	$ 10.01	$ 9.87
Service Based Options [Member]
Stock Option Assumptions
Expected term (in years)	5.89	5.91
Expected volatility	39.41%	40.22%
Expected dividend yield	2.07%	1.94%
Risk-free interest rate	1.16%	1.65%
Weighted-average market value of underlying stock at grant date	$ 27.05	$ 29.10
Weighted average exercise price	$ 27.05	$ 29.10
Weighted-average fair value of options granted during the period	$ 8.42	$ 9.58

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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