Condensed Consolidated Statements of Earnings - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 174,436	$ 157,029
Cost of sales	119,105	107,934
Gross margin	55,331	49,095
Operating expenses:
Selling expenses	15,430	14,126
Research and development expenses	2,700	2,895
General and administrative expenses	10,923	5,594
Total operating expenses	29,053	22,615
Earnings from operations	26,278	26,480
Other expenses:
Interest expense, net	1,696	1,589
Other, net	92	98
Total other expenses (income)	1,788	1,687
Earnings before income tax expense	24,490	24,793
Income tax expense	4,722	6,010
Net earnings	$ 19,768	$ 18,783
Net earnings per common share - basic (in dollars per share)	$ 0.62	$ 0.58
Net earnings per common share - diluted (in dollars per share)	$ 0.61	$ 0.58