Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Total revenues	$ 196,129	$ 184,158	$ 177,325
Costs and expenses
Cost of sales (excludes amortization of intangible assets of $6,341, $6,283, and $6,079, respectively)	71,688	74,180	66,976
Research and development	35,514	37,913	34,186
Sales and marketing	47,886	43,076	35,744
General and administrative	29,447	25,811	25,581
Amortization of intangible assets from acquired businesses and technology	8,856	8,828	8,171
Impairment loss	0	3,558	0
Facility restructuring charge	0	0	1,825
Total costs and expenses	193,391	193,366	172,483
Operating income (loss)	2,738	(9,208)	4,842
Interest expense, net	(12,035)	(1,775)	(1,408)
(Loss) income before benefit for income taxes	(9,297)	(10,983)	3,434
Benefit for income taxes	(3,218)	(3,909)	(3,956)
Net (loss) income	$ (6,079)	$ (7,074)	$ 7,390
Basic (loss) earnings per share	$ (0.18)	$ (0.21)	$ 0.22
Diluted (loss) earnings per share	$ (0.18)	$ (0.21)	$ 0.21
Shares used in basic per share calculations	34,104	34,451	33,836
Shares used in diluted per share calculations	34,104	34,451	34,947