Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Total revenues	$ 38,267	$ 39,133	$ 111,959	$ 89,454
Costs and expenses
Cost of sales (excludes amortization of intangible assets of $1,623, $1,590, $3,245 and $3,180, respectively)	17,755	17,318	41,325	36,567
Research and development	7,627	9,656	15,502	22,363
Sales and marketing	12,360	12,206	25,915	24,523
General and administrative	6,783	6,430	13,903	13,600
Amortization of intangible assets from acquired businesses and technology	2,390	2,290	4,681	4,509
One-time acquisition costs	2,379	252	2,431	371
Total costs and expenses	49,294	48,152	103,757	101,933
Operating (loss) income	(11,027)	(9,019)	8,202	(12,479)
Interest expense, net	(2,778)	(2,924)	(5,603)	(5,613)
(Loss) income before income taxes	(13,805)	(11,943)	2,599	(18,092)
(Benefit) provision for income taxes	(1,963)	(4,103)	151	(6,806)
Net (loss) income	$ (11,842)	$ (7,840)	$ 2,448	$ (11,286)
Basic earnings (loss) per share (in dollars per share)	$ (0.35)	$ (0.24)	$ 0.07	$ (0.35)
Diluted earnings (loss) per share (in dollars per share)	$ (0.35)	$ (0.24)	$ 0.07	$ (0.35)
Shares used in basic per share calculation (in shares)	33,500	32,541	33,351	32,632
Shares used in diluted per share calculation (in shares)	33,500	32,541	34,295	32,632