Condensed Consolidated Statements of Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Consolidated Statements of Income (unaudited) [Abstract]
Net sales	$ 318,401	$ 278,721
Cost of sales	242,630	206,765
Gross profit	75,771	71,956
Selling, general, administrative and engineering expenses	53,121	43,806
Income from operations	22,650	28,150
Interest expense	265	467
Other income, net of expenses	512	544
Income from operations before income taxes	22,897	28,227
Income taxes	7,817	10,549
Net income	15,080	17,678
Net loss attributable to non-controlling interest	(40)	(65)
Net income attributable to controlling interest	$ 15,120	$ 17,743
Net income attributable to controlling interest:
Basic (in dollars per share)	$ 0.66	$ 0.77
Diluted (in dollars per share)	$ 0.65	$ 0.77
Weighted average number of common shares outstanding:
Basic (in shares)	23,013	22,965
Diluted (in shares)	23,176	23,135
Dividends declared per common share (in dollars per share)	$ 0.10	$ 0.10