Income Taxes (Summary of Activity Related to Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018	Sep. 27, 2020	Sep. 29, 2019
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Beginning balance	$ 132.1	$ 224.6	$ 196.9
Increase related to prior year tax positions	11.1	3.8	17.5
Decrease related to prior year tax positions	(0.5)	(75.3)	(41.8)
Increase related to current year tax positions	9.8	18.5	62.4
Decreases related to settlements with taxing authorities	0.0	(16.4)	(4.5)
Decreases related to lapsing of statute of limitations	(28.8)	(23.1)	(5.9)
Ending balance	123.7	132.1	224.6
Gross unrecognized tax benefits	123.7	224.6	196.9	$ 123.7	$ 132.1
Unrecognized tax benefits affecting the effective tax rate if recognized				103.0
Interest and penalties expense/(benefit) recognized in income tax expense	$ 3.0	$ (2.8)	$ (0.5)
Accrued interest and penalties				13.0	$ 10.0
Maximum [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Amount of reasonably possible unrecognized benefit change				$ 39.0

The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

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Amount of unrecognized tax benefits.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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