Accumulated Other Comprehensive Income (Loss) - Summary of Accumulated Other Comprehensive Income, Net of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 27, 2019	Sep. 28, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 668,675	$ 777,374
Ending balance	313,896	668,675
Foreign currency translation loss, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,637	3,139
Other comprehensive income	1,693	(502)
Ending balance	4,330	2,637
Other Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(449)	(162)
Ending balance	28	(449)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,188	2,977
Ending balance	4,358	2,188
Unrealized loss on short-term investments, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income	$ 477	$ (287)

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(31))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_StockholdersEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant