CONSOLIDATED STATEMENTS OF INCOME (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]
Net sales	$ 253,253	$ 222,141	$ 739,459	$ 636,989
Cost of goods sold	160,227	142,582	472,604	418,224
Gross profit	93,026	79,559	266,855	218,765
Selling, general, and administrative expenses	39,071	40,575	117,708	122,296
Technical and research expenses	9,958	10,553	30,473	30,788
Restructuring expenses, net	2,552	5,503	13,714	10,220
Operating income	41,445	22,928	104,960	55,461
Interest expense, net	4,621	4,429	13,530	13,042
Other (income)/expense, net	(3,151)	(530)	(973)	2,854
Income before income taxes	39,975	19,029	92,403	39,565
Income tax expense	11,491	3,809	23,131	12,138
Net income	28,484	15,220	69,272	27,427
Net income/(loss) attributable to the noncontrolling interest	269	(49)	447	202
Net income attributable to the Company	$ 28,215	$ 15,269	$ 68,825	$ 27,225
Earnings per share attributable to Company shareholders - Basic	$ 0.87	$ 0.47	$ 2.13	$ 0.85
Earnings per share attributable to Company shareholders - Diluted	$ 0.87	$ 0.47	$ 2.13	$ 0.85
Shares of the Company used in computing earnings per share:
Basic	32,264	32,187	32,247	32,160
Diluted	32,280	32,214	32,263	32,193
Dividends declared per share, Class A and Class B	$ 0.17	$ 0.17	$ 0.51	$ 0.51