401(k) Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Defined Contribution Plan [Abstract]
Contributions made by company	$ 19.6	$ 19.2	$ 18.6
Advertising cost	$ 15.6	$ 29.5	$ 26.9

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 35
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

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