SEGMENTS - Major Product Categories and Percentage of Consolidated Net Sales (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Product Information [Line Items]
Net sales	$ 339,153	$ 626,053	$ 726,227	$ 1,159,227
Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	100.00%	100.00%	100.00%	100.00%
Eliminations
Product Information [Line Items]
Net sales	$ (7,884)	$ (6,654)	$ (15,013)	$ (15,022)
Commercial Trailer Products
Product Information [Line Items]
Net sales	232,247	400,401	483,192	740,546
Commercial Trailer Products | Operating Segments
Product Information [Line Items]
Net sales	232,254	400,864	483,229	741,909
Commercial Trailer Products | Eliminations
Product Information [Line Items]
Net sales	7	463	37	1,363
Diversified Products
Product Information [Line Items]
Net sales	56,074	90,835	131,933	183,015
Diversified Products | Operating Segments
Product Information [Line Items]
Net sales	63,951	97,026	146,909	196,674
Diversified Products | Eliminations
Product Information [Line Items]
Net sales	7,877	6,191	14,976	13,659
Final Mile Products
Product Information [Line Items]
Net sales	50,832	134,817	111,102	235,666
Final Mile Products | Operating Segments
Product Information [Line Items]
Net sales	50,832	134,817	111,102	235,666
Final Mile Products | Eliminations
Product Information [Line Items]
Net sales	0	0	0	0
New trailers
Product Information [Line Items]
Net sales	$ 246,929	$ 435,167	$ 528,142	$ 806,785
New trailers | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	72.80%	69.50%	72.70%	69.60%
New trailers | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0
New trailers | Commercial Trailer Products | Operating Segments
Product Information [Line Items]
Net sales	218,753	385,842	456,654	711,661
New trailers | Diversified Products | Operating Segments
Product Information [Line Items]
Net sales	28,176	49,325	71,488	95,124
New trailers | Final Mile Products | Operating Segments
Product Information [Line Items]
Net sales	0	0	0	0
Used trailers
Product Information [Line Items]
Net sales	$ 3,596	$ 752	$ 5,124	$ 1,476
Used trailers | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	1.10%	0.10%	0.70%	0.10%
Used trailers | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0
Used trailers | Commercial Trailer Products | Operating Segments
Product Information [Line Items]
Net sales	2,273	13	2,591	150
Used trailers | Diversified Products | Operating Segments
Product Information [Line Items]
Net sales	1,323	739	2,533	1,326
Used trailers | Final Mile Products | Operating Segments
Product Information [Line Items]
Net sales	0	0	0	0
Components, parts and service
Product Information [Line Items]
Net sales	$ 26,306	$ 37,501	$ 58,282	$ 79,214
Components, parts and service | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	7.80%	6.00%	8.00%	6.80%
Components, parts and service | Eliminations
Product Information [Line Items]
Net sales	$ (7,884)	$ (6,575)	$ (14,984)	$ (14,495)
Components, parts and service | Commercial Trailer Products | Operating Segments
Product Information [Line Items]
Net sales	9,571	10,622	18,843	20,955
Components, parts and service | Diversified Products | Operating Segments
Product Information [Line Items]
Net sales	22,166	29,007	48,248	64,891
Components, parts and service | Final Mile Products | Operating Segments
Product Information [Line Items]
Net sales	2,453	4,447	6,175	7,863
Equipment and other
Product Information [Line Items]
Net sales	$ 62,322	$ 152,633	$ 134,679	$ 271,752
Equipment and other | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	18.40%	24.40%	18.50%	23.40%
Equipment and other | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ (79)	$ (29)	$ (527)
Equipment and other | Commercial Trailer Products | Operating Segments
Product Information [Line Items]
Net sales	1,657	4,387	5,141	9,143
Equipment and other | Diversified Products | Operating Segments
Product Information [Line Items]
Net sales	12,286	17,955	24,640	35,333
Equipment and other | Final Mile Products | Operating Segments
Product Information [Line Items]
Net sales	$ 48,379	$ 130,370	$ 104,927	$ 227,803