Valuation and Qualifying Accounts - (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Sep. 28, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 46.5	$ 41.1	$ 63.1
Provision to  Allowance for Doubtful Accounts	14.5	6.6	4.0
Write-offs Adjustments Charged to Allowance	(2.7)	(1.2)	(26.0)
Balance at End of Period	58.3	46.5	41.1
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	99.7	101.6	105.8
Increases	39.1	6.7	5.3
Deductions	(0.9)	(8.6)	(9.5)
Balance at End of Period	$ 137.9	$ 99.7	$ 101.6