Goodwill and Intangible Assets Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 26, 2020	Mar. 27, 2020	Dec. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Jun. 26, 2020	Jun. 28, 2019	Sep. 27, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 429,745						$ 429,745		$ 425,705
Accumulated Amortization	(269,676)						(269,676)		(244,814)
Total	160,069						160,069		180,891
Purchases of intangible assets	0	$ 0	$ 2,900	$ 10,200	$ 5,000	$ 12,100	$ 2,900	$ 27,300
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			14 years	5 years 4 months 24 days	4 years	11 years 7 months 6 days	14 years	7 years 10 months 24 days
Amortization of Intangible Assets	7,400			$ 7,600			$ 22,200	$ 21,600
Acquired Patents And Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	342,072						342,072		338,075
Accumulated Amortization	(198,839)						(198,839)		(176,867)
Total	143,233						143,233		161,208
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	64,724						64,724		64,728
Accumulated Amortization	(48,167)						(48,167)		(45,510)
Total	16,557						16,557		19,218
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	22,949						22,949		22,902
Accumulated Amortization	(22,670)						(22,670)		(22,437)
Total	$ 279						$ 279		$ 465