Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Earnings [Abstract]
Net sales	$ 553,204	$ 552,492	$ 541,383
Cost of sales	372,343	384,395	397,211
Gross margin	180,861	168,097	144,172
Operating expenses:
Selling expenses	55,172	46,255	35,758
Research and development expenses	7,325	5,990	4,810
General and administrative expenses	27,526	21,896	21,461
Total operating expenses	90,023	74,141	62,029
Earnings from operations	90,838	93,956	82,143
Other expenses (income):
Interest income	(9)	(9)	(64)
Interest expense	7,265	6,593	5,145
Other, net	648	309	10
Earnings before income tax expense	82,934	87,063	77,052
Income tax expense	26,962	27,341	24,226
Net earnings	$ 55,972	$ 59,722	$ 52,826
Basic net earnings per common share (in dollars per share)	$ 1.78	$ 1.92	$ 1.74
Diluted net earnings per common share (in dollars per share)	$ 1.75	$ 1.89	$ 1.69