Share-Based Payments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Nov. 17, 2018	Nov. 18, 2017	Nov. 17, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of options granted	$ 208.31	$ 128.93
Stock options granted	171,293	282,820
Stock options exercised - Shares	129,559		24,761
Stock options exercised - Weighted average exercise price	$ 359.94		$ 284.04
share-based compensation expense	$ 10.5		$ 11.1
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of options granted	$ 772.80
Restricted stock units granted	10,474
Non vested restricted stock unit award	$ 7.0
Estimated weighted average period	4 years
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anti-dilutive shares excluded from the computation of earnings per share	427,407	802,195

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The number of grants made 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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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

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

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