Condensed Consolidated Statements of Earnings - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 175,140	$ 158,595	$ 522,931	$ 477,178
Cost of sales	118,772	104,587	355,852	320,157
Gross margin	56,368	54,008	167,079	157,021
Operating expenses:
Selling expenses	14,224	15,227	43,490	44,847
Research and development expenses	2,692	2,699	7,961	8,446
General and administrative expenses	10,424	10,052	33,405	24,816
Total operating expenses	27,340	27,978	84,856	78,109
Earnings from operations	29,028	26,030	82,223	78,912
Other expenses:
Interest expense, net	953	1,672	3,609	4,749
Other, net	168	(78)	244	53
Total other expenses (income)	1,121	1,594	3,853	4,802
Earnings before income tax expense	27,907	24,436	78,370	74,110
Income tax expense	6,339	3,760	15,909	14,822
Net earnings	$ 21,568	$ 20,676	$ 62,461	$ 59,288
Net earnings per common share - basic (in dollars per share)	$ 0.67	$ 0.64	$ 1.94	$ 1.84
Net earnings per common share - diluted (in dollars per share)	$ 0.66	$ 0.64	$ 1.92	$ 1.82