Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 703,644	$ 643,705	$ 643,679
Cost of sales	479,747	432,338	439,427
Gross margin	223,897	211,367	204,252
Operating expenses:
Selling expenses	58,630	60,932	57,219
Research and development expenses	10,332	11,377	11,592
General and administrative expenses	43,788	36,505	28,341
Total operating expenses	112,750	108,814	97,152
Earnings from operations	111,147	102,553	107,100
Other expenses:
Interest expense, net	4,439	5,959	7,611
Other, net	291	116	459
Total other expenses	4,730	6,075	8,070
Earnings before income tax expense	106,417	96,478	99,030
Income tax expense	21,794	16,807	20,457
Net earnings	$ 84,623	$ 79,671	$ 78,573
Basic net earnings per common share (in dollars per share)	$ 2.63	$ 2.48	$ 2.45
Diluted net earnings per common share (in dollars per share)	$ 2.60	$ 2.45	$ 2.42