401(k) Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Defined Contribution Plan [Abstract]
Contributions made by company	$ 19.2	$ 18.6	$ 20.2

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration