Summary of Significant Accounting Policies - Schedule of Inventories (Detail) - USD ($) $ in Millions	Sep. 26, 2020	Sep. 28, 2019
Accounting Policies [Abstract]
Raw materials	$ 152.3	$ 166.1
Work-in-process	46.5	54.5
Finished goods	196.3	224.3
Inventories	$ 395.1	$ 444.9

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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