Goodwill and Intangible Assets Finite-Lived Intangible Assets (Details) - USD ($)	3 Months Ended				9 Months Ended
	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Cost	$ 394,369,000				$ 394,369,000		$ 379,292,000
Accumulated Amortization	(209,229,000)				(209,229,000)		(189,644,000)
Total	185,140,000				185,140,000		189,648,000
Purchases of intangible assets	$ 700	$ 2,800		$ 5,300	$ 12,543,000	$ 5,250,000
Intangible Assets, Explanation of Significant Additions			12		15.5	5.3
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years	5 years 3 months	14 years 1 month	18 years	12 years 1 month	18 years
Amortization of Intangible Assets	$ 6,700,000			$ 7,300,000	$ 19,800,000	$ 24,000,000
Acquired Patents And Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	314,799,000				314,799,000		299,707,000
Accumulated Amortization	(146,549,000)				(146,549,000)		(128,986,000)
Total	168,250,000				168,250,000		170,721,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	56,836,000				56,836,000		56,843,000
Accumulated Amortization	(40,345,000)				(40,345,000)		(38,368,000)
Total	16,491,000				16,491,000		18,475,000
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	22,734,000				22,734,000		22,742,000
Accumulated Amortization	(22,335,000)				(22,335,000)		(22,290,000)
Total	$ 399,000				$ 399,000		$ 452,000