Share Based Compensation (Summary Of Stock Option Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2012
Share Based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Beginning Balance	136,575	291,625
Grants	36,294
Exercised	(23,588)	(153,700)
Forfeitures	(2,983)	(1,350)
Shares outstanding	146,298	136,575	291,625
Average exercised price beginning balance	$ 23.17	$ 23.23
Granted	$ 58.10
Exercised	$ 24.10	$ 23.28
Forfeitures	$ 58.10	$ 24.33
Averaged exercised price ending balance	$ 30.97	$ 23.17	$ 23.23
Average remaining conractual term (years)	3 years 1 month 6 days	3 years 1 month 6 days	3 years 8 months 23 days
Average intrinsic value outstanding	$ 5,031	$ 5,331	$ 3,977
Exercised aggregate intrinsic value	971	7,001
Number of Shares Exercisable	136,575	284,875		112,987
Exercisable average exercise price	$ 23.17	$ 23.33		$ 22.97
Average remaining contractual term (years) Exercisable	2 years 4 months 24 days	3 years 1 month 6 days	3 years 8 months 12 days
Intrinsic value of options exercised	$ 4,789	$ 5,331	$ 3,858

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Net number of share options (or share units) granted during the period.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Number of share options (or share units) exercised during the current period.

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