Revenue and Segment Information - Revenue, Income, Goodwill and Identifiable Assets by Location (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Sales	$ 238,087	$ 215,389
Income from Operations	21,361	20,251
Goodwill	85,033		$ 84,761
Total Identifiable Assets	745,894		639,671
Industrial
Segment Reporting Information [Line Items]
Net Sales	132,167	125,816
Income from Operations	11,800	12,570
Goodwill	61,469		61,682
Total Identifiable Assets	394,818		369,271
Agricultural
Segment Reporting Information [Line Items]
Net Sales	58,647	51,777
Income from Operations	5,253	4,859
Goodwill	6,359		6,357
Total Identifiable Assets	171,137		141,023
European
Segment Reporting Information [Line Items]
Net Sales	47,273	37,796
Income from Operations	4,308	$ 2,822
Goodwill	17,205		16,722
Total Identifiable Assets	$ 179,939		$ 129,377