Share-Based Payments (Details) (USD $)	3 Months Ended	9 Months Ended
May 07, 2011	May 08, 2010	May 07, 2011	May 08, 2010
Weighted average fair value of the stock option awards granted, weighted average key assumptions:
Expected price volatility			31.00%	31.00%
Risk-free interest rate			1.00%	1.80%
Weighted average expected lives (in years)			4.3	4.3
Forfeiture rate			10.00%	10.00%
Dividend yield			0.00%	0.00%
Share-Based Payments (Textuals)
Total share-based expense related to stock options and share purchase plans	$ 6,400,000	$ 4,300,000	$ 18,500,000	$ 13,200,000
Stock options granted			424,780	496,580
Weighted average grant date fair value of options granted			$ 58.58	$ 40.75
Anti-dilutive shares excluded from the computation of earnings per share	0	0	1,260	24,900
Restricted stock units granted under Director Compensation Program, description			Under the Program, restricted stock units are granted the first day of each calendar quarter. The number of restricted stock units granted each quarter is determined by dividing one-fourth of the amount of the annual retainer by the fair market value of the shares of common stock as of the grant date.
Stock options exercised - shares			436,394	380,503
Stock options exercised, weighted average exercise price	$ 99.87	$ 77.27	$ 99.87	$ 77.27
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based expense related to stock options and share purchase plans	$ 466,000		$ 932,000

This is the estimated percentage of options granted that are expected to be forfeited or canceled before becoming fully vested. This estimate is based on historical experience at the time of valuation and reduces expenses ratably over the vesting period. An increase in the forfeiture rate will decrease compensation expense. This estimate is evaluated periodically based on the extent to which actual forfeitures differ, or are expected to differ, from the previous estimate.

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Description of the deferred compensation arrangement, including fixed amounts and determinable awards, or the method for determining payments and awards, the timing of such payments and awards, and any requisite service or performance criteria, as of the balance sheet date.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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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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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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