Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net sales:
Net sales	$ 1,163,466	$ 1,119,138	$ 1,008,822
Cost of sales	871,356	845,911	752,707
Gross profit	292,110	273,227	256,115
Selling, general and administrative expenses	184,199	172,921	151,522
Amortization expense	14,746	5,658	3,505
Income from operations	93,165	94,648	101,088
Interest expense	(15,837)	(10,747)	(5,493)
Interest income	1,366	1,229	410
Other income	(557)	(795)	(1,474)
Income before income taxes	78,137	84,335	94,531
Provision for income taxes	21,507	21,429	21,045
Net income	$ 56,630	$ 62,906	$ 73,486
Net income per common share:
Basic (in dollars per share)	$ 4.81	$ 5.36	$ 6.30
Diluted (in dollars per share)	$ 4.78	$ 5.33	$ 6.25
Average common shares:
Basic (in shares)	11,782	11,729	11,660
Diluted (in shares)	11,845	11,800	11,761
Industrial
Net sales:
Net sales	$ 811,161	$ 768,454	$ 638,198
Income from operations	59,881	65,262	65,077
Agricultural
Net sales:
Net sales	352,305	350,684	370,624
Income from operations	$ 33,284	$ 29,386	$ 36,011