Employee Stock Plans (Stock Option and RSU Transactions) (Details) - USD ($) shares in Millions, $ in Millions	6 Months Ended
Mar. 28, 2021	Sep. 27, 2020
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Stock Options	0.0
Options exercised, Stock Options	(2.2)
Forfeited/expired, Stock Options	(0.1)
Total unrecognized stock-based compensation expense, net of estimated forfeitures, Stock Options	$ 0.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6.9	9.2
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, RSUs	3.9
RSUs vested, RSUs	(3.0)
Forfeited/expired, RSUs	(0.8)
Total unrecognized stock-based compensation expense, net of estimated forfeitures, RSUs	$ 253.8
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	8.4	8.3

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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- Definition

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

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

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

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