Share Plans (Schedule of Share Option Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
Dec. 30, 2016	Dec. 29, 2017	Sep. 30, 2016	Sep. 25, 2015	Sep. 26, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Intrinsic value of options vested	$ 0.3	$ 1.4	$ 15.3	$ 89.5
Share Option Activity [Roll Forward]
Beginning balance	3,421,856	3,386,694	2,786,443	3,526,789
Granted	3,742	1,719,532	1,248,828	635,567
Exercised	(16,382)	(113,605)	(413,830)	(1,132,778)
Expired/Forfeited	(22,522)	(348,637)	(199,585)	(243,135)
Ending balance	3,386,694	4,643,984	3,421,856	2,786,443
Share options vested and unvested expected to vest		3,882,733
Share options exerciseable		1,944,709
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-average exercise price, outstanding share options	$ 61.24	$ 57.78	$ 61.17	$ 52.76	$ 36.84
Weighted-average exercise price, granted share options	60.01	51.57	72.44	102.20
Weighted-average exercise price, exercised share options	36.42	47.74	32.76	29.79
Weighted-average exercise price, expired and forfeited share options	$ 70.82	68.08	$ 72.65	$ 58.00
Weighted-average exercise price, vested and unvested expected to vest share options		60.62
Weighted-average exercise price, exercisable share options		$ 52.19
Weighted-average remaining contractual term, outstanding share options		6 years 11 months
Weighted-average remaining contractual term, vested and unvested expected to vest share options		7 years 6 months
Weighted-average remaining contractual term, exercisable share options		4 years 8 months
Aggregate intrinsic value, outstanding share options		$ 0.2
Aggregate intrinsic value, vested and unvested expected to vest share options		(0.6)
Aggregate intrinsic value, exercisable share options		0.2
Tax benefit from stock options exercised	$ 0.1	$ 0.5	$ 5.7	$ 33.1

Amount of deferred tax expense from write-off of the deferred tax asset related to deductible stock options at exercise.

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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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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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 per share amount at which grantees can acquire shares of common stock by exercise of options.

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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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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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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 remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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