Business Segment Information (Financial Information By Reportable Segment) (Details) $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 05, 2017 segment	May 08, 2017 segment	Apr. 01, 2017 USD ($)	Apr. 02, 2016 USD ($)	Apr. 01, 2017 USD ($) segment	Apr. 02, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment					2
Revenues			$ 193,424	$ 137,098	$ 392,703	$ 277,599
Total income from operations			15,412	4,371	25,702	17,972
Test [Member]
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Revenues			123,840	113,797	254,966	232,607
Total income from operations			6,367	1,715	18,083	12,102
Sensors [Member]
Segment Reporting Information [Line Items]
Revenues			69,584	23,301	137,737	44,992
Total income from operations			$ 9,045	$ 2,656	$ 7,619	$ 5,870
Scenario, Forecast [Member]
Segment Reporting Information [Line Items]
Number of operating segments | segment		3