Condensed Consolidated Statements of Earnings - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 173,355	$ 161,554	$ 347,791	$ 318,583
Cost of sales	117,975	107,636	237,080	215,570
Gross margin	55,380	53,918	110,711	103,013
Operating expenses:
Selling expenses	13,836	15,494	29,266	29,620
Research and development expenses	2,569	2,852	5,269	5,747
General and administrative expenses	12,058	9,170	22,981	14,764
Total operating expenses	28,463	27,516	57,516	50,131
Earnings from operations	26,917	26,402	53,195	52,882
Other expenses:
Interest expense, net	960	1,488	2,656	3,077
Other, net	(16)	33	76	131
Total other expenses (income)	944	1,521	2,732	3,208
Earnings before income tax expense	25,973	24,881	50,463	49,674
Income tax expense	4,848	5,052	9,570	11,062
Net earnings	$ 21,125	$ 19,829	$ 40,893	$ 38,612
Net earnings per common share - basic (in dollars per share)	$ 0.66	$ 0.62	$ 1.27	$ 1.20
Net earnings per common share - diluted (in dollars per share)	$ 0.65	$ 0.61	$ 1.26	$ 1.19