Industry Segments - Schedule of reporting information by segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 138,388	$ 135,219	$ 140,560	$ 152,568	$ 140,106	$ 135,113	$ 135,252	$ 136,572	$ 566,735	$ 547,043	$ 534,379
Total operating income									6,327	24,888	27,362
Interest expense, net									(4,938)	(7,292)	(8,643)
Loss on extinguishment of debt					1,900				0	(1,888)	0
Income from continuing operations before income taxes									1,389	15,708	18,719
Identifiable Assets	348,645				355,942				348,645	355,942	381,684
Capital Additions, Net									5,123	5,814	12,489
Depreciation and Amortization									26,139	30,831	31,792
Operating Segments [Member] | Material Handling [Member]
Segment Reporting Information [Line Items]
Net sales									417,199	391,313	363,956
Total operating income									57,948	38,874	40,776
Identifiable Assets	229,962				257,863				229,962	257,863	268,634
Capital Additions, Net									4,500	5,165	10,933
Depreciation and Amortization									24,159	28,506	29,270
Operating Segments [Member] | Distribution [Member]
Segment Reporting Information [Line Items]
Net sales									149,636	156,428	170,660
Total operating income									7,441	9,073	12,834
Identifiable Assets	48,575				49,822				48,575	49,822	56,072
Capital Additions, Net									587	622	1,424
Depreciation and Amortization									1,169	1,174	1,221
Operating Segments [Member] | Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	0				0				0	0	20,707
Inter-company sales [Member]
Segment Reporting Information [Line Items]
Net sales									(100)	(698)	(237)
Corporate [Member]
Segment Reporting Information [Line Items]
Total operating income									(59,062)	(23,059)	(26,248)
Identifiable Assets	$ 70,108				$ 48,257				70,108	48,257	36,271
Capital Additions, Net									36	27	132
Depreciation and Amortization									$ 811	$ 1,151	$ 1,301