Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011	Dec. 31, 2011
Summarized Segment Financial Information
Net sales to external customers	$ 137,357	$ 146,070	$ 438,620	$ 444,507
Segment operating earnings before corporate and shared services charges	13,694	13,608	35,977	36,348
Corporate and shared services charges	(6,012)	(5,854)	(16,819)	(17,614)
Segment operating earnings	7,682	7,754	19,158	18,734
Total assets	481,376	516,475	481,376	516,475	480,815
Components and Sensors [Member]
Summarized Segment Financial Information
Net sales to external customers	75,565	69,089	228,806	209,158
Segment operating earnings before corporate and shared services charges	9,492	7,738	25,233	26,388
Corporate and shared services charges	(4,185)	(3,557)	(11,543)	(11,601)
Segment operating earnings	5,307	4,181	13,690	14,787
Total assets	369,614	367,387	369,614	367,387
EMS [Member]
Summarized Segment Financial Information
Net sales to external customers	61,792	76,981	209,814	235,349
Segment operating earnings before corporate and shared services charges	4,202	5,870	10,744	9,960
Corporate and shared services charges	(1,827)	(2,297)	(5,276)	(6,013)
Segment operating earnings	2,375	3,573	5,468	3,947
Total assets	$ 111,762	$ 149,088	$ 111,762	$ 149,088