Segment Information - Information About Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Apr. 01, 2012
Segment Reporting Information [Line Items]
Product revenue	$ 74,672	$ 71,407
Service revenue	6,220	6,302
Operating income	17,981	17,741
MVSD [Member]
Segment Reporting Information [Line Items]
Product revenue	68,319	64,221
Service revenue	2,092	1,920
Operating income	22,076	21,144
SISD [Member]
Segment Reporting Information [Line Items]
Product revenue	6,353	7,186
Service revenue	4,128	4,382
Operating income	1,732	2,392
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Product revenue
Service revenue
Operating income	$ (5,827)	$ (5,795)