Restructuring and Related Charges (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Oct. 29, 2018 segment	Sep. 30, 2019 USD ($) segment	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Oct. 01, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of reportable segments | segment	3	2	2
Restructuring and related cost, expected cost						$ 3,000
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of the period			$ 710	$ 3,542	$ 13,217
Restructuring charges related to two-segment realignment			12,993	10,422	31,665
Restructuring charges related to other initiatives (including VSP)			2,444	11,085	32,392
Write-off charge and other non‑cash activity			(541)	(663)	(727)
Cash payments			(12,966)	(13,280)	(41,432)
Other adjustments			(82)	26	92
Restructuring reserve, end of the period		$ 655	655	710	3,542
Two-segment realignment [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges related to two-segment realignment			$ 11,090	$ 0	$ 0