Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 1,207,815	$ 1,139,447	$ 969,236
Cost of sales	956,710	926,618	784,708
Gross margin	251,105	212,829	184,528
Selling, general, and administrative expense	153,489	144,280	128,972
Research and development expense	15,187	13,981	12,802
Restructuring expense	5,599	644	2,586
Other - net	15,334	13,893	11,288
Operating profit	61,496	40,031	28,880
Interest expense - net	2,471	2,183	1,789
Other non-operating expense-net	42,683	1,452	1,776
Income before income taxes	16,342	36,396	25,315
Income tax (benefit) expense	(4,504)	24,945	(425)
Net income	$ 20,846	$ 11,451	$ 25,740
Basic earnings per share:
Net income per share of common stock (in usd per share)	$ 1.03	$ 0.57	$ 1.29
Diluted earnings per share:
Net income per share of common stock (in usd per share)	1.01	0.56	1.27
Cash dividends per share	$ 0.415	$ 0.395	$ 0.375
Weighted-average number of shares of common stock outstanding:
Basic	20,212	20,027	19,983
Diluted	20,613	20,415	20,213