Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Sep. 28, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (46,078)	$ (383,798)	$ (139,977)
Unrealized gain (loss) on short-term investments, net of tax	193	477	(287)
Foreign currency translation gain (loss), net of tax	458	1,693	(502)
Other comprehensive income (loss), net of tax	651	2,170	(789)
Total comprehensive loss	$ (45,427)	$ (381,628)	$ (140,766)