Business Segment Information (Financial Information By Reportable Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Oct. 03, 2015	Sep. 27, 2014	Sep. 28, 2013
Segment Reporting Information [Line Items]
Total revenue	$ 563,934	$ 564,328	$ 569,439
Total income from operations	61,496	60,256	79,955
Total identifiable assets	460,831	487,408	451,277
Goodwill	27,677	26,123	16,624
Capital expenditures	18,445	20,038	29,690
Depreciation and amortization	21,106	19,279	16,589
Test [Member]
Segment Reporting Information [Line Items]
Total revenue	462,880	458,153	474,119
Total income from operations	42,285	39,847	60,984
Total identifiable assets	369,515	392,825	360,037
Goodwill	26,243	24,584	15,028
Capital expenditures	14,652	16,553	26,775
Depreciation and amortization	18,342	16,560	14,325
Sensors [Member]
Segment Reporting Information [Line Items]
Total revenue	101,054	106,175	95,320
Total income from operations	19,211	20,409	18,971
Total identifiable assets	91,316	94,583	91,240
Goodwill	1,434	1,539	1,596
Capital expenditures	3,793	3,485	2,915
Depreciation and amortization	$ 2,764	$ 2,719	$ 2,264