Goodwill & Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 18,394
Goodwill [Roll Forward]
Goodwill	311,087	$ 309,616
Goodwill, Translation and Purchase Accounting Adjustments	(1,499)	1,471
Goodwill	327,982	311,087	$ 309,616
Finite-Lived Intangible Assets, Net [Abstract]
Cost	400,166	379,292
Accumulated Amortization	(216,147)	(189,644)
Net	184,019	189,648
Payments to acquire intangible assets	12,543	5,250	121,020
Amortization of intangible assets	26,500	30,900	$ 33,200
Acquired patents and technology
Finite-Lived Intangible Assets, Net [Abstract]
Cost	319,082	299,707
Accumulated Amortization	(152,775)	(128,986)
Net	166,307	170,721
Payments to acquire intangible assets	$ 21,000	$ 5,300
Weighted-average useful life	10 years 6 months	18 years
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Cost	$ 58,342	$ 56,843
Accumulated Amortization	(41,012)	(38,368)
Net	17,330	18,475
Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Cost	22,742	22,742
Accumulated Amortization	(22,360)	(22,290)
Net	$ 382	$ 452