Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 02, 2011 Years Year EmployeeGroup BusinessSegment OptionPlan	Oct. 03, 2010	Oct. 02, 2011 Year Years EmployeeGroup BusinessSegment OptionPlan	Oct. 03, 2010
Information about the Company's segments
Product revenue	$ 74,165	$ 69,288	$ 220,608	$ 190,968
Service	5,920	5,705	17,264	14,803
Operating income	22,389	22,275	63,799	52,768
Segment Information (Textual) [Abstract]
Number of reportable segments	2		2
MVSD [Member]
Information about the Company's segments
Product revenue	66,404	61,454	200,163	170,459
Service	1,771	1,618	5,574	4,768
Operating income	23,422	24,651	72,036	63,035
SISD [Member]
Information about the Company's segments
Product revenue	7,761	7,834	20,445	20,509
Service	4,149	4,087	11,690	10,035
Operating income	2,891	2,290	5,910	3,292
Reconciling Items [Member]
Information about the Company's segments
Operating income	$ (3,924)	$ (4,666)	$ (14,147)	$ (13,559)