Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Operations
Net sales	$ 419,349	$ 542,082	$ 475,686
Cost of sales	261,155	348,363	299,458
Gross profit	158,194	193,719	176,228
Operating expenses, net:
Research and development	90,557	97,755	81,987
Selling, general, and administrative	79,749	92,060	100,250
Amortization of intangible assets	17,085	32,351	35,475
Restructuring	6,403	8,556	11,851
Acquisition costs		2,959	17,786
Asset impairment	4,020	375,172	1,139
Other operating expense (income), net	(42)	368	(392)
Total operating expenses, net	197,772	609,221	248,096
Operating income (loss)	(39,578)	(415,502)	(71,868)
Interest income	4,680	3,186	2,335
Interest expense	(22,085)	(21,518)	(19,457)
Other income (expense), net	(20,973)
Income (loss) before income taxes	(77,956)	(433,834)	(88,990)
Income tax expense (benefit)	777	(26,746)	(37,594)
Net income (loss)	$ (78,733)	$ (407,088)	$ (51,396)
Income (loss) per common share:
Basic (in dollars per share)	$ (1.66)	$ (8.63)	$ (1.16)
Diluted (in dollars per share)	$ (1.66)	$ (8.63)	$ (1.16)
Weighted average number of shares:
Basic (in shares)	47,482	47,151	44,174
Diluted (in shares)	47,482	47,151	44,174