Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Net sales	$ 135,219	$ 135,113	$ 428,347	$ 406,937
Total operating income (loss)	(25,839)	6,801	(706)	20,885
Interest expense, net	(883)	(1,838)	(3,835)	(5,828)
Income (loss) from continuing operations before income taxes	(26,722)	4,963	(4,541)	15,057
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales	97,682	95,192	317,621	289,700
Total operating income (loss)	10,812	10,015	44,865	30,675
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales	37,557	40,004	110,815	117,836
Total operating income (loss)	2,546	3,179	7,070	7,742
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales	(20)	(83)	(89)	(599)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income (loss)	$ (39,197)	$ (6,393)	$ (52,641)	$ (17,532)