Segment and Geographic Information - Information About the Company's Segments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Product revenue	$ 295,588	$ 297,310	$ 263,463
Service revenue	28,691	24,604	27,228
Depreciation and amortization	10,858	9,756	9,809
Goodwill and intangibles	96,459	100,939	105,334
Operating income	83,407	85,355	75,713
MVSD [Member]
Segment Reporting Information [Line Items]
Product revenue	263,308	264,956	234,052
Service revenue	10,388	8,717	13,362
Depreciation and amortization	9,505	8,445	8,683
Goodwill and intangibles	90,390	94,322	98,252
Operating income	89,378	94,201	88,342
SISD [Member]
Segment Reporting Information [Line Items]
Product revenue	32,280	32,354	29,411
Service revenue	18,303	15,887	13,866
Depreciation and amortization	963	908	757
Goodwill and intangibles	6,069	6,617	7,082
Operating income	11,941	10,301	5,064
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	390	403	369
Operating income	$ (17,912)	$ (19,147)	$ (17,693)