Goodwill and intangible Assets Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 26, 2015	Jun. 26, 2015	Jun. 27, 2014	Sep. 26, 2014
Finite-Lived Intangible Assets [Line Items]
Cost	$ 237,623	$ 237,623		$ 168,673
Accumulated Amortization	(119,897)	(119,897)		(104,973)
Total	117,726	117,726		63,700
Purchases of intangible assets		(22,716)	$ (19,950)
Acquired Patents And Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	158,782	158,782		99,262
Accumulated Amortization	(71,465)	(71,465)		(61,678)
Total	87,317	87,317		37,584
Purchases of intangible assets	(16,300)	$ (22,700)
Weighted average useful life		18 years
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	56,934	$ 56,934		30,717
Accumulated Amortization	(26,821)	(26,821)		(22,739)
Total	30,113	30,113		7,978
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	21,907	21,907		38,694
Accumulated Amortization	(21,611)	(21,611)		(20,556)
Total	$ 296	$ 296		$ 18,138