Business Segment Information (Financial Information By Reportable Segment) (Details) $ in Thousands	3 Months Ended
Dec. 29, 2018 USD ($) segment	Dec. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment	2
Total revenue	$ 203,181	$ 194,162
Total income from operations	17,966	16,497
Test & Simulation
Segment Reporting Information [Line Items]
Total revenue	125,560	118,203
Total income from operations	7,331	5,609
Sensors
Segment Reporting Information [Line Items]
Total revenue	77,950	75,959
Total income from operations	10,634	10,888
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total revenue	(329)	0
Total income from operations	$ 1	$ 0

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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