Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 152,568	$ 136,572
Operating Income	12,022	8,116
Interest expense, net	(1,639)	(2,130)
Income from continuing operations before income taxes	10,383	5,986
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	116,809	98,482
Operating Income	16,730	12,846
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	35,781	38,574
Operating Income	1,738	1,538
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(22)	(484)
Corporate [Member]
Segment Reporting Information [Line Items]
Operating Income	$ (6,446)	$ (6,268)