Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 140,106	$ 135,113	$ 135,252	$ 136,572	$ 123,289	$ 125,669	$ 138,244	$ 147,177	$ 547,043	$ 534,379	$ 571,020
Operating Income									24,888	27,362	34,517
Interest expense, net									(7,292)	(8,643)	(9,009)
Loss on extinguishment of debt	1,900								(1,888)	0	0
Income from continuing operations before income taxes									15,708	18,719	25,508
Identifiable Assets	355,942				381,684				355,942	381,684	429,024
Capital Additions, Net									5,814	12,489	21,787
Depreciation and Amortization									30,831	31,792	32,330
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales									391,313	363,956	384,351
Operating Income									38,874	40,776	53,418
Identifiable Assets	257,863				268,634				257,863	268,634	307,799
Capital Additions, Net									5,165	10,933	19,482
Depreciation and Amortization									28,506	29,270	30,018
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales									156,428	170,660	187,637
Operating Income									9,073	12,834	16,114
Identifiable Assets	49,822				56,072				49,822	56,072	58,772
Capital Additions, Net									622	1,424	1,795
Depreciation and Amortization									1,174	1,221	998
Operating Segments [Member] | Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	0				20,707				0	20,707	27,707
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales									(698)	(237)	(968)
Corporate [Member]
Segment Reporting Information [Line Items]
Operating Income									(23,059)	(26,248)	(35,015)
Identifiable Assets	$ 48,257				$ 36,271				48,257	36,271	34,746
Capital Additions, Net									27	132	510
Depreciation and Amortization									$ 1,151	$ 1,301	$ 1,314