Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 347,337	$ 343,374	$ 331,378
Cost of goods sold	172,526	168,489	169,243
Gross profit	174,811	174,885	162,135
Operating expenses
Sales and marketing	41,888	43,159	42,315
General and administrative	61,244	50,167	49,842
Research and development	20,018	17,071	18,125
Total operating expenses	123,150	110,397	110,282
Operating income	51,661	64,488	51,853
Interest expense	13,617	17,405	18,410
Loss on extinguishment of debt	3,196	0	2,442
Other expense (income)	6,221	(2,465)	(8,638)
Income before income taxes	28,627	49,548	39,639
Income tax (benefit) expense	(3,040)	9,030	(83,746)
Net income	$ 31,667	$ 40,518	$ 123,385
Net income per common share:
Basic (in dollars per share)	$ 0.81	$ 1.06	$ 3.31
Diluted (in dollars per share)	$ 0.79	$ 1.03	$ 3.17
Weighted-average common shares outstanding:
Basic (in shares)	38,988	38,233	37,276
Diluted (in shares)	40,113	39,501	38,892