Stock Option Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance	3 years
Performance award expense	$ (354)	$ (976)	$ (1,296)
Pre-tax stock-based compensation expense associated with stock options	9,500	9,900	8,300
Tax benefit associated with stock options	$ 3,100	$ 3,200	$ 2,700
Weighted average fair value for options granted, per share	$ 9.94	$ 11.44	$ 8.18
Total intrinsic value of options exercised	$ 18,800	$ 21,500	$ 33,700
Shares reserved	11,693,263
Aggregate intrinsic value of options outstanding	$ 43,700
Aggregate intrinsic value of options exercisable	43,700
Total fair value of shares vested	29,300	$ 35,500	29,800
Unrecognized compensation expense related to non-vested stock options granted	$ 7,500
Annual dividend yield	1.60%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years of service that options were still issued with a reload provision to officers until Fiscal 2011	5 years
Annual dividend yield		1.60%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years of service when options with a reload provision were no longer issued to officers beginning in Fiscal 2006	5 years
Annual dividend yield		1.40%
Two Thousand Ten Master Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance award expense	$ 100	$ 700	$ 100
Two Thousand Ten Master Stock Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable from date of the grant, in years	10 years
Reload Grants [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable from date of the grant, in years	4 years	6 years	5 years
Non Officer Original Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable from date of the grant, in years	7 years	7 years	7 years
Director Original Grants Without Reloads [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable from date of the grant, in years	8 years	8 years	8 years
After Fiscal Two Thousand Ten [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, years	3 years
After Fiscal Two Thousand Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, years	3 years