Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenues	$ 82,630	$ 81,359
Cost of goods sold	40,321	41,597
Gross profit	42,309	39,762
Operating expenses
Sales and marketing	10,640	10,214
General and administrative	12,543	12,270
Research and development	3,989	5,351
Total operating expenses	27,172	27,835
Operating income	15,137	11,927
Interest expense	4,050	5,420
Loss on extinguishment of debt	0	2,161
Other income	(920)	(577)
Income before income taxes	12,007	4,923
Income tax expense	3,796	785
Net income	$ 8,211	$ 4,138
Net income per common share:
Basic (in dollars per share)	$ 0.22	$ 0.11
Diluted (in dollars per share)	$ 0.21	$ 0.11
Weighted-average common shares outstanding:
Basic (in shares)	37,886	36,889
Diluted (in shares)	39,493	38,601