Consolidated Income Statements (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Gross sales	$ 104,231	$ 112,233	$ 390,575	$ 350,431
Commissions, allowances and rebates	240	225	641	1,468
Net sales	103,991	112,008	389,934	348,963
Other revenues, net	627	611	7,827	3,216
Net revenue	104,618	112,619	397,761	352,179
Cost of goods sold	71,893	65,676	249,389	200,802
Gross profit	32,725	46,943	148,372	151,377
Operating expenses:
Selling, general and administrative expenses	14,514	17,167	47,037	50,678
Research and development expenses	4,191	4,233	11,943	12,590
Acquisition and integration expenses	7,388		7,727
Total operating expenses	26,093	21,400	66,707	63,268
Operating profit	6,632	25,543	81,665	88,109
Other expenses/(income):
Interest expense, net	725	337	824	991
Unrealized gain on investment in equity securities	(5,611)		(10,757)
Other expenses, net	109	432	554	1,119
Income before income taxes	11,409	24,774	91,044	85,999
(Benefit)/provision for income taxes	(15,406)	7,498	(872)	22,484
Income from continuing operations	26,815	17,276	91,916	63,515
(Loss)/income from discontinued operations, net of tax	(86)	20	(710)	(1,324)
Net income	$ 26,729	$ 17,296	$ 91,206	$ 62,191
Basic earnings/(loss) per share of common stock:
Income from continuing operations	$ 0.80	$ 0.53	$ 2.77	$ 1.95
Loss from discontinued operations, net of tax	0.00	0.00	(0.02)	(0.04)
Net income	0.80	0.53	2.75	1.91
Diluted earnings/(loss) per share of common stock:
Income from continuing operations	0.79	0.52	2.73	1.90
Loss from discontinued operations, net of tax	0.00	0.00	(0.02)	(0.04)
Net income	$ 0.79	$ 0.52	$ 2.71	$ 1.86
Weighted average shares outstanding:
Basic	33,406	32,749	33,130	32,612
Effect of dilutive stock based compensation	486	763	573	839
Diluted	33,892	33,512	33,703	33,451