Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net sales	$ 140,560	$ 135,252	$ 293,128	$ 271,824
Operating Income	13,111	5,968	25,133	14,084
Interest expense, net	(1,313)	(1,860)	(2,952)	(3,990)
Income from continuing operations before income taxes	11,798	4,108	22,181	10,094
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	103,130	96,026	219,939	194,508
Operating Income	17,323	7,814	34,053	20,660
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	37,477	39,258	73,258	77,832
Operating Income	2,786	3,025	4,524	4,563
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(47)	(32)	(69)	(516)
Corporate [Member]
Segment Reporting Information [Line Items]
Operating Income	$ (6,998)	$ (4,871)	$ (13,444)	$ (11,139)