Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Total revenues	$ 277,743	$ 191,603	$ 196,129
Cost of sales	121,601	79,872	78,029
Gross profit	156,142	111,731	118,100
Research and development	33,644	38,672	35,514
Sales and marketing	67,248	50,436	50,401
General and administrative	29,192	26,351	27,057
Acquisition and integration costs	16,506	711	2,390
Total operating expenses	146,590	116,170	115,362
Operating income (loss)	9,552	(4,439)	2,738
Interest expense, net	(17,588)	(11,760)	(12,035)
Loss before taxes	(8,036)	(16,199)	(9,297)
Provision (benefit) for income taxes	129	(2,391)	(3,218)
Net loss	$ (8,165)	$ (13,808)	$ (6,079)
Basic and diluted loss per share	$ (0.24)	$ (0.42)	$ (0.18)
Shares used in basic and diluted per share calculation	33,734	32,708	34,104