Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands		12 Months Ended
		Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Accounts Notes Loans And Financing Receivable Gross Allowance And Net [Abstract]
Beginning balance		$ 16,035	$ 17,028	$ 10,050
Charged to expense		2,936	1,647	9,690
Other	[1]	(486)	0	0
Write-offs		(2,282)	(2,640)	(2,712)
Ending balance		$ 16,203	$ 16,035	$ 17,028

[1] Other includes divestitures.