Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 03, 2020	Jun. 28, 2019	Jul. 03, 2020	Jun. 28, 2019
Income Statement [Abstract]
Revenue	$ 137,267	$ 108,306	$ 382,788	$ 387,460
Cost of revenue	66,391	74,478	190,338	219,678
Gross profit	70,876	33,828	192,450	167,782
Operating expenses:
Research and development	34,948	42,708	105,936	128,593
Selling, general and administrative	29,982	41,920	94,317	126,437
Restructuring (benefit) charges	(554)	8,887	1,494	17,047
Total operating expenses	64,376	357,601	201,747	536,163
Income (loss) from operations	6,500	(323,773)	(9,297)	(368,381)
Other expense:
Warrant liability (expense) gain	(19,511)	1,927	(14,951)	5,788
Interest expense, net	(5,849)	(8,967)	(22,142)	(27,142)
Other (expense) income, net	(4,372)	4,777	(12,464)	(4,233)
Total other expense, net	(29,732)	(2,263)	(49,557)	(25,587)
Loss before income taxes	(23,232)	(326,036)	(58,854)	(393,968)
Income tax expense (benefit)	1,750	(1,322)	4,716	346
Net loss	$ (24,982)	$ (324,714)	$ (63,570)	$ (394,314)
Net loss per share:
Loss per share - Basic	$ (0.37)	$ (4.93)	$ (0.96)	$ (6.01)
Loss per share - Diluted	$ (0.37)	$ (4.95)	$ (0.96)	$ (6.09)
Weighted average shares used:
Basic (in shares)	66,796	65,858	66,512	65,555
Diluted (in shares)	66,796	65,945	66,512	65,722
Impairment of Long-Lived Assets Held-for-use	$ 0	$ 264,086	$ 0	$ 264,086