Goodwill & Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 37,094
Goodwill [Roll Forward]
Goodwill	277,574	$ 279,724
Goodwill, Translation and Purchase Accounting Adjustments	(6,960)	(2,150)
Goodwill	307,708	277,574	$ 279,724
Finite-Lived Intangible Assets, Net [Abstract]
Cost	252,284	168,673
Accumulated Amortization	124,777	104,973
Net	127,507	63,700
Payments to acquire intangible assets	37,416	37,950	4,050
Amortization of intangible assets	21,000	15,100	$ 15,800
Acquired patents and technology
Finite-Lived Intangible Assets, Net [Abstract]
Cost	172,787	99,262
Accumulated Amortization	74,398	61,678
Net	98,389	37,584
Payments to acquire intangible assets	$ 37,400	$ 38,000
Weighted-average useful life	18 years	13 years 7 months 6 days
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Cost	$ 56,933	$ 30,717
Accumulated Amortization	28,275	22,739
Net	28,658	7,978
Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Cost	22,564	38,694
Accumulated Amortization	22,104	20,556
Net	460	$ 18,138
Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	700
Doremi Labs [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	36,400
Goodwill [Roll Forward]
Goodwill	$ 39,672
Doremi Labs [Member] | Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Weighted-average useful life	10 years