Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Jun. 26, 2020	Jun. 28, 2019	Sep. 27, 2019
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 15,851	$ 124	$ 124
Restructuring charges	$ (1,522)	$ (30,232)	(1,866)	(30,264)	(36,558)
Cash payments			(22,040)		(7,713)
Non-cash and other adjustments			4,323		(13,118)
Restructuring reserve, ending balance	0		0		15,851
Severance
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			128	0	0
Restructuring charges			0		(3,134)
Cash payments			(75)		(3,006)
Non-cash and other adjustments			(53)		0
Restructuring reserve, ending balance	0		0		128
Leased facility exit costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			15,723	0	0
Restructuring charges			(1,866)		(18,261)
Cash payments			(21,965)		(4,577)
Non-cash and other adjustments			4,376		2,039
Restructuring reserve, ending balance	0		0		15,723
Fixed assets write-off
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	0	0
Restructuring charges			0		(15,216)
Cash payments			0		0
Non-cash and other adjustments			0		(15,216)
Restructuring reserve, ending balance	0		0		0
Other associated costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	$ 124	124
Restructuring charges			0		53
Cash payments			0		(130)
Non-cash and other adjustments			0		59
Restructuring reserve, ending balance	$ 0		$ 0		$ 0