Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales:
Net sales	$ 1,008,822	$ 912,380	$ 844,748
Cost of sales	752,707	677,687	639,649
Gross profit	256,115	234,693	205,099
Selling, general and administrative expenses	155,027	145,955	137,479
Income from operations	101,088	88,738	67,620
Interest expense	(5,493)	(4,839)	(5,914)
Interest income	410	336	214
Other income	(1,474)	(1,868)	269
Income before income taxes	94,531	82,367	62,189
Provision for income taxes	21,045	38,052	22,144
Net income	$ 73,486	$ 44,315	$ 40,045
Net income per common share:
Basic (in dollars per share)	$ 6.30	$ 3.84	$ 3.50
Diluted (in dollars per share)	$ 6.25	$ 3.79	$ 3.46
Average common shares:
Basic (in shares)	11,660	11,549	11,434
Diluted (in shares)	11,761	11,682	11,565
Industrial
Net sales:
Net sales	$ 598,930	$ 522,706	$ 484,088
Income from operations	64,213	51,914	35,984
Agricultural
Net sales:
Net sales	235,069	227,389	205,834
Income from operations	22,649	24,059	20,720
European
Net sales:
Net sales	174,823	162,285	154,826
Income from operations	$ 14,226	$ 12,765	$ 10,916