Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Sep. 29, 2018
Income Statement [Abstract]
Net sales	$ 1,228,999	$ 1,430,640	$ 1,902,573
Cost of sales	818,125	944,175	1,071,882
Gross profit	410,874	486,465	830,691
Operating expenses:
Research and development	115,578	117,353	132,586
Selling, general and administrative	270,464	272,257	293,632
Goodwill and other impairment charges	451,025	0	766
Amortization of intangible assets	3,987	13,760	10,690
Total operating expenses	841,054	403,370	437,674
Income (loss) from operations	(430,180)	83,095	393,017
Other income (expense):
Interest income	1,053	1,119	1,571
Interest expense	(17,037)	(19,122)	(25,847)
Other—net	3,441	(5,044)	(7,186)
Total other expense, net	(12,543)	(23,047)	(31,462)
Income (loss) from continuing operations before income taxes	(442,723)	60,048	361,555
Provision for (benefit from) income taxes	(28,584)	6,223	114,195
Net income (loss) from continuing operations	(414,139)	53,825	247,360
Loss from discontinued operations, net of income taxes	0	0	(2)
Net income (loss)	$ (414,139)	$ 53,825	$ 247,358
Basic net income (loss) per share:
Income per share from continuing operations (in dollars per share)	$ (17.18)	$ 2.23	$ 10.07
Loss per share from discontinued operations, net of income taxes (in dollars per share)	0	0	0
Net income per share (in dollars per share)	(17.18)	2.23	10.07
Diluted net income (loss) per share:
Income per share from continuing operations (in dollars per share)	(17.18)	2.22	9.95
Loss per share from discontinued operations, net of income taxes (in dollars per share)	0	0	0
Net income per share (in dollars per share)	$ (17.18)	$ 2.22	$ 9.95
Shares used in computation:
Basic (in shares)	24,105	24,118	24,572
Diluted (in shares)	24,105	24,279	24,851