Goodwill & Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 9,367	$ 18,394
Goodwill [Roll Forward]
Goodwill	327,982	311,087
Goodwill, Translation and Purchase Accounting Adjustments	(2,520)	(1,499)
Goodwill	334,829	327,982	$ 311,087
Finite-Lived Intangible Assets, Net [Abstract]
Cost	425,705	400,166
Accumulated Amortization	(244,814)	(216,147)
Net	180,891	184,019
Amortization of intangible assets	29,700	26,500	$ 30,900
Acquired patents and technology
Finite-Lived Intangible Assets, Net [Abstract]
Cost	338,075	319,082
Accumulated Amortization	(176,867)	(152,775)
Net	161,208	166,307
Payments to acquire intangible assets	$ 27,300	$ 21,000
Weighted-average useful life	7 years 10 months 24 days	10 years 6 months
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Cost	$ 64,728	$ 58,342
Accumulated Amortization	(45,510)	(41,012)
Net	19,218	17,330
Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Cost	22,902	22,742
Accumulated Amortization	(22,437)	(22,360)
Net	$ 465	$ 382

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

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