Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net sales	$ 174,429	$ 122,250
Total operating income	10,865	23,298
Interest expense, net	(995)	(1,069)
Income before income taxes	9,870	22,229
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	129,893	84,076
Total operating income	16,927	15,167
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	44,550	38,195
Total operating income	1,438	1,850
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(14)	(21)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (7,500)	$ 6,281