Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014 segment	Jun. 29, 2013
Segment Reporting Information [Line Items]
Number of operating segments			2
Revenue	$ 145,471	$ 135,059	$ 421,224	$ 414,644
Income from operations	17,398	16,428	43,899	52,108
Test [Member]
Segment Reporting Information [Line Items]
Revenue	118,194	110,378	342,602	345,424
Income from operations	11,769	10,878	29,351	39,275
Sensors [Member]
Segment Reporting Information [Line Items]
Revenue	27,277	24,681	78,622	69,220
Income from operations	$ 5,629	$ 5,550	$ 14,548	$ 12,833