Business Segment Information (Financial Information By Reportable Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Segment Reporting Information [Line Items]
Revenue	$ 787,955	$ 650,147	$ 563,934
Income from Operations	54,828	41,763	61,496
Identifiable Assets	1,189,692	1,188,020	460,831
Goodwill	369,762	369,700	27,677
Capital Expenditures	17,798	20,806	18,445
Depreciation and Amortization	35,523	24,077	21,106
Test [Member]
Segment Reporting Information [Line Items]
Revenue	504,087	512,265	462,880
Income from Operations	28,622	40,660	42,285
Identifiable Assets	374,698	395,067	369,515
Goodwill	25,109	25,022	26,243
Capital Expenditures	13,281	17,570	14,652
Depreciation and Amortization	17,275	17,279	18,342
Sensors [Member]
Segment Reporting Information [Line Items]
Revenue	283,868	137,882	101,054
Income from Operations	26,206	1,103	19,211
Identifiable Assets	814,994	792,953	91,316
Goodwill	344,653	344,678	1,434
Capital Expenditures	4,517	3,236	3,793
Depreciation and Amortization	$ 18,248	$ 6,798	$ 2,764