Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net sales	$ 118,394	$ 134,285	$ 240,644	$ 273,400
Total operating income	12,256	10,182	35,554	20,400
Interest expense, net	(1,194)	(1,017)	(2,263)	(2,066)
Income from continuing operations before income taxes	11,062	9,165	33,291	18,334
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	80,855	95,902	164,931	198,853
Total operating income	15,796	17,589	30,963	33,796
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	37,541	38,395	75,736	74,569
Total operating income	1,636	3,328	3,486	3,541
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(2)	(12)	(23)	(22)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (5,176)	$ (10,735)	$ 1,105	$ (16,937)