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Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Restructuring (Details) - USD ($) $ in Thousands	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 124
Restructuring charges	$ (30,232)	$ 82	(30,264)	$ 446
Cash payments			(658)
Non-cash charges			13,118
Restructuring reserve, ending balance	16,612		16,612
Severance
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Restructuring charges			(2,854)
Cash payments			(528)
Non-cash charges
Restructuring reserve, ending balance	2,326		2,326
Leased facility exit costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Restructuring charges			(12,247)
Cash payments
Non-cash charges			(2,039)
Restructuring reserve, ending balance	14,286		14,286
Fixed assets write-off
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Restructuring charges			(15,216)
Cash payments
Non-cash charges			15,216
Restructuring reserve, ending balance	0		0
Other associated costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			124
Restructuring charges			53
Cash payments			(130)
Non-cash charges			(59)
Restructuring reserve, ending balance	$ 0		$ 0