Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net sales	$ 134,285	$ 140,560	$ 273,400	$ 293,128
Total operating income	10,182	13,111	20,400	25,133
Interest expense, net	(1,017)	(1,313)	(2,066)	(2,952)
Income from continuing operations before income taxes	9,165	11,798	18,334	22,181
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	95,902	103,130	198,853	219,939
Total operating income	17,589	17,323	33,796	34,053
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	38,395	37,477	74,569	73,258
Total operating income	3,328	2,786	3,541	4,524
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(12)	(47)	(22)	(69)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (10,735)	$ (6,998)	$ (16,937)	$ (13,444)