Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 85,776	$ 88,900	$ 257,991	$ 257,103
Cost of goods sold	44,187	44,015	127,745	126,063
Gross profit	41,589	44,885	130,246	131,040
Operating expenses
Sales and marketing	10,151	10,478	31,496	33,248
General and administrative	18,061	13,609	43,943	37,727
Research and development	4,860	4,316	15,584	12,520
Total operating expenses	33,072	28,403	91,023	83,495
Operating income	8,517	16,482	39,223	47,545
Interest expense	2,356	4,446	11,491	12,794
Loss on extinguishment of debt	0	0	3,196	0
Other expense (income)	804	(799)	(1,695)	(2,055)
Income before income taxes	5,357	12,835	26,231	36,806
Income tax expense	501	3,566	5,014	9,581
Net income	$ 4,856	$ 9,269	$ 21,217	$ 27,225
Net income per common share:
Basic (in dollars per share)	$ 0.12	$ 0.24	$ 0.55	$ 0.71
Diluted (in dollars per share)	$ 0.12	$ 0.24	$ 0.53	$ 0.69
Weighted-average common shares outstanding:
Basic (in shares)	39,123	38,342	38,901	38,155
Diluted (in shares)	40,286	39,402	40,123	39,467