Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net sales	$ 200,058	$ 132,258	$ 561,856	$ 372,902
Total operating income	11,817	13,140	38,551	48,694
Interest expense, net	(1,056)	(1,204)	(3,050)	(3,467)
Income before income taxes	10,761	11,936	35,501	45,227
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	149,664	86,769	416,784	251,700
Total operating income	15,066	15,593	49,895	46,556
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	50,413	45,517	145,119	121,253
Total operating income	4,377	5,091	10,029	8,577
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(19)	(28)	(47)	(51)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (7,626)	$ (7,544)	$ (21,373)	$ (6,439)