SEGMENTS - Major Product Categories and Percentage of Consolidated Net Sales (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Product Information [Line Items]
Net sales	$ 387,074	$ 533,174
Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	100.00%	100.00%
Eliminations
Product Information [Line Items]
Net sales	$ (7,129)	$ (8,368)
Commercial Trailer Products
Product Information [Line Items]
Net sales	250,945	340,145
Commercial Trailer Products \| Operating Segments
Product Information [Line Items]
Net sales	250,975	341,045
Commercial Trailer Products \| Eliminations
Product Information [Line Items]
Net sales	30	900
Diversified Products
Product Information [Line Items]
Net sales	75,859	92,180
Diversified Products \| Operating Segments
Product Information [Line Items]
Net sales	82,958	99,648
Diversified Products \| Eliminations
Product Information [Line Items]
Net sales	7,099	7,468
Final Mile Products
Product Information [Line Items]
Net sales	60,270	100,849
Final Mile Products \| Operating Segments
Product Information [Line Items]
Net sales	60,270	100,849
Final Mile Products \| Eliminations
Product Information [Line Items]
Net sales	0	0
New trailers
Product Information [Line Items]
Net sales	$ 281,213	$ 371,618
New trailers \| Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	72.70%	69.70%
New trailers \| Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0
New trailers \| Commercial Trailer Products \| Operating Segments
Product Information [Line Items]
Net sales	237,901	325,819
New trailers \| Diversified Products \| Operating Segments
Product Information [Line Items]
Net sales	43,312	45,799
New trailers \| Final Mile Products \| Operating Segments
Product Information [Line Items]
Net sales	0	0
Used trailers
Product Information [Line Items]
Net sales	$ 1,528	$ 724
Used trailers \| Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	0.40%	0.10%
Used trailers \| Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0
Used trailers \| Commercial Trailer Products \| Operating Segments
Product Information [Line Items]
Net sales	318	137
Used trailers \| Diversified Products \| Operating Segments
Product Information [Line Items]
Net sales	1,210	587
Used trailers \| Final Mile Products \| Operating Segments
Product Information [Line Items]
Net sales	0	0
Components, parts and service
Product Information [Line Items]
Net sales	$ 31,976	$ 41,713
Components, parts and service \| Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	8.30%	7.80%
Components, parts and service \| Eliminations
Product Information [Line Items]
Net sales	$ (7,100)	$ (7,920)
Components, parts and service \| Commercial Trailer Products \| Operating Segments
Product Information [Line Items]
Net sales	9,272	10,333
Components, parts and service \| Diversified Products \| Operating Segments
Product Information [Line Items]
Net sales	26,082	35,884
Components, parts and service \| Final Mile Products \| Operating Segments
Product Information [Line Items]
Net sales	3,722	3,416
Equipment and other
Product Information [Line Items]
Net sales	$ 72,357	$ 119,119
Equipment and other \| Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	18.70%	22.30%
Equipment and other \| Eliminations
Product Information [Line Items]
Net sales	$ (29)	$ (448)
Equipment and other \| Commercial Trailer Products \| Operating Segments
Product Information [Line Items]
Net sales	3,484	4,756
Equipment and other \| Diversified Products \| Operating Segments
Product Information [Line Items]
Net sales	12,354	17,378
Equipment and other \| Final Mile Products \| Operating Segments
Product Information [Line Items]
Net sales	$ 56,548	$ 97,433