Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements of Operations
Net sales	$ 112,078	$ 108,954	$ 315,216	$ 306,147
Cost of sales	62,936	66,731	177,761	192,924
Gross profit	49,142	42,223	137,455	113,223
Operating expenses, net:
Research and development	19,129	22,639	57,577	68,901
Selling, general, and administrative	19,415	20,962	55,541	60,620
Amortization of intangible assets	3,831	4,312	11,502	12,773
Restructuring		1,828	1,097	3,874
Asset impairment			281
Other operating expense (income), net	(218)	(153)	(502)	(232)
Total operating expenses, net	42,157	49,588	125,496	145,936
Operating income (loss)	6,985	(7,365)	11,959	(32,713)
Interest income	231	1,219	1,458	3,749
Interest expense	(6,425)	(5,549)	(18,131)	(16,491)
Loss on extinguishment of debt			(3,046)
Income (loss) before income taxes	791	(11,695)	(7,760)	(45,455)
Income tax expense (benefit)	211	72	530	407
Net income (loss)	$ 580	$ (11,767)	$ (8,290)	$ (45,862)
Income (loss) per common share:
Basic (in dollars per share)	$ 0.01	$ (0.25)	$ (0.17)	$ (0.97)
Diluted (in dollars per share)	$ 0.01	$ (0.25)	$ (0.17)	$ (0.97)
Weighted average number of shares:
Basic (in shares)	48,341	47,489	48,327	47,361
Diluted (in shares)	49,174	47,489	48,327	47,361