Business Segment Information (Financial Information By Reportable Segment) (Details) $ in Thousands			3 Months Ended		9 Months Ended
	Jan. 06, 2017 segment	Jan. 05, 2017 segment	Jul. 01, 2017 USD ($)	Jul. 02, 2016 USD ($)	Jul. 01, 2017 USD ($) segment	Jul. 02, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3				2
Total revenue			$ 193,764	$ 157,700	$ 586,467	$ 435,299
Total income (loss) from operations			16,617	9,689	42,319	27,661
Test
Segment Reporting Information [Line Items]
Number of operating segments | segment		2
Total revenue			124,359	133,512	379,325	366,119
Total income (loss) from operations			8,709	10,683	26,792	22,785
Sensors
Segment Reporting Information [Line Items]
Total revenue			69,405	24,188	207,142	69,180
Total income (loss) from operations			$ 7,908	$ (994)	$ 15,527	$ 4,876