Goodwill and Intangible Assets Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 25, 2021	Jun. 26, 2020	Jun. 25, 2021	Jun. 26, 2020	Sep. 25, 2020
Finite-Lived Intangible Assets [Line Items]
Cost	$ 430,671		$ 430,671		$ 430,346
Accumulated Amortization	(301,457)		(301,457)		(277,915)
Total	129,214		129,214		152,431
Purchases of intangible assets				$ 2,900
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				14 years
Amortization of Intangible Assets	7,300	$ 7,400	21,900	$ 22,200
Acquired Patents And Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	342,939		342,939		342,637
Accumulated Amortization	(226,981)		(226,981)		(206,123)
Total	115,958		115,958		136,514
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	64,751		64,751		64,740
Accumulated Amortization	(51,681)		(51,681)		(49,062)
Total	13,070		13,070		15,678
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	22,981		22,981		22,969
Accumulated Amortization	(22,795)		(22,795)		(22,730)
Total	$ 186		$ 186		$ 239