Fair Value Measurements - Cash and Cash Equivalents (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 28, 2024	Sep. 28, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	$ 1,782.1	$ 2,160.2
Short-Term Investments, Unrealized Gain	0.4
Short-Term Investments, Unrealized Loss	0.0
Total available-for-sale securities	406.6	992.9
Cash, Cash Equivalents, and Short-Term Investments	2,020.2
Cash, Cash Equivalents, and Short-Term Investments, Fair Value	2,020.6
Investments	238.5
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	1,614.0
Unrealized Gains	0.0
Unrealized Losses	0.0
Fair Value	1,614.0
Money Market Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	152.1
Fair Value	152.1	341.7
Short-Term Investments, Unrealized Gain	0.0
Short-Term Investments, Unrealized Loss	0.0
Investments	0.0
US Treasury Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	16.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	254.1
Investments, Unrealized Gain	0.4
Investments, Unrealized Loss	0.0
Total available-for-sale securities	254.5	$ 626.3
Investments	$ 238.5

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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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Sum of the carrying amounts as of the balance sheet date of all investments.

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