Summary of Significant Accounting Policies - Accounts Receivable Reserve Activity (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 24, 2022	Sep. 25, 2021
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	$ 37.7	$ 40.5	$ 31.6
Charged to Costs and Expenses	3.7	4.2	15.0
Write- offs and Payments	(2.9)	(7.0)	(6.1)
Balance at End of Period	$ 38.5	$ 37.7	$ 40.5