Goodwill and Intangible Assets Finite-Lived Intangible Assets (Details) - USD ($)	3 Months Ended			6 Months Ended
	Mar. 30, 2018	Dec. 29, 2017	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Cost	$ 394,761,000			$ 394,761,000		$ 379,292,000
Accumulated Amortization	(203,421,000)			(203,421,000)		(189,644,000)
Total	191,340,000			191,340,000		189,648,000
Purchases of intangible assets	$ 2,800		$ 5,000	$ 11,893,000	$ 5,250,000
Intangible Assets, Explanation of Significant Additions		12		14.8	5.3
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years 3 months	14 years 1 month	18 years	12 years 6 months	18 years
Amortization of Intangible Assets	$ 6,600,000		$ 8,400,000
Acquired Patents And Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	315,125,000			$ 315,125,000		299,707,000
Accumulated Amortization	(141,355,000)			(141,355,000)		(128,986,000)
Total	173,770,000			173,770,000		170,721,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	56,866,000			56,866,000		56,843,000
Accumulated Amortization	(39,713,000)			(39,713,000)		(38,368,000)
Total	17,153,000			17,153,000		18,475,000
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	22,770,000			22,770,000		22,742,000
Accumulated Amortization	(22,353,000)			(22,353,000)		(22,290,000)
Total	$ 417,000			$ 417,000		$ 452,000