SEGMENTS - Major Product Categories and Percentage of Consolidated Net Sales (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Product Information [Line Items]
Net sales	$ 351,584	$ 580,908	$ 1,077,811	$ 1,740,135
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	$ (2,300)	$ (6,121)	$ (17,313)	$ (21,143)
Commercial Trailer Products Segment
Product Information [Line Items]
Net sales	226,324	380,062	709,516	1,120,608
Commercial Trailer Products Segment | Operating Segments
Product Information [Line Items]
Net sales	226,516	380,344	709,745	1,122,253
Commercial Trailer Products Segment | Eliminations
Product Information [Line Items]
Net sales	192	282	229	1,645
Diversified Products Segment
Product Information [Line Items]
Net sales	69,912	87,342	201,845	270,357
Diversified Products Segment | Operating Segments
Product Information [Line Items]
Net sales	72,020	93,181	218,929	289,855
Diversified Products Segment | Eliminations
Product Information [Line Items]
Net sales	2,108	5,839	17,084	19,498
Final Mile Products Segment
Product Information [Line Items]
Net sales	55,348	113,504	166,450	349,170
Final Mile Products Segment | Operating Segments
Product Information [Line Items]
Net sales	55,348	113,504	166,450	349,170
Final Mile Products Segment | Eliminations
Product Information [Line Items]
Net sales	0	0	0	0
New trailers
Product Information [Line Items]
Net sales	$ 253,064	$ 418,635	$ 781,206	$ 1,225,420
New trailers | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	72.00%	72.10%	72.50%	70.40%
New trailers | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0
New trailers | Commercial Trailer Products Segment | Operating Segments
Product Information [Line Items]
Net sales	215,609	366,938	672,263	1,078,599
New trailers | Diversified Products Segment | Operating Segments
Product Information [Line Items]
Net sales	37,455	51,697	108,943	146,821
New trailers | Final Mile Products Segment | Operating Segments
Product Information [Line Items]
Net sales	0	0	0	0
Used trailers
Product Information [Line Items]
Net sales	$ 1,961	$ 503	$ 7,085	$ 1,979
Used trailers | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	0.60%	0.10%	0.70%	0.10%
Used trailers | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0
Used trailers | Commercial Trailer Products Segment | Operating Segments
Product Information [Line Items]
Net sales	522	86	3,113	236
Used trailers | Diversified Products Segment | Operating Segments
Product Information [Line Items]
Net sales	1,439	417	3,972	1,743
Used trailers | Final Mile Products Segment | Operating Segments
Product Information [Line Items]
Net sales	0	0	0	0
Components, parts and service
Product Information [Line Items]
Net sales	$ 26,781	$ 32,171	$ 85,063	$ 111,385
Components, parts and service | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	7.60%	5.50%	7.90%	6.40%
Components, parts and service | Eliminations
Product Information [Line Items]
Net sales	$ (2,300)	$ (5,960)	$ (17,284)	$ (20,455)
Components, parts and service | Commercial Trailer Products Segment | Operating Segments
Product Information [Line Items]
Net sales	9,371	10,039	28,214	30,994
Components, parts and service | Diversified Products Segment | Operating Segments
Product Information [Line Items]
Net sales	16,607	23,790	64,855	88,681
Components, parts and service | Final Mile Products Segment | Operating Segments
Product Information [Line Items]
Net sales	3,103	4,302	9,278	12,165
Equipment and other
Product Information [Line Items]
Net sales	$ 69,778	$ 129,599	$ 204,457	$ 401,351
Equipment and other | Sales Revenue, Net
Product Information [Line Items]
Percentage of consolidated net sales	19.80%	22.30%	19.00%	23.10%
Equipment and other | Eliminations
Product Information [Line Items]
Net sales	$ 0	$ (161)	$ (29)	$ (688)
Equipment and other | Commercial Trailer Products Segment | Operating Segments
Product Information [Line Items]
Net sales	1,014	3,281	6,155	12,424
Equipment and other | Diversified Products Segment | Operating Segments
Product Information [Line Items]
Net sales	16,519	17,277	41,159	52,610
Equipment and other | Final Mile Products Segment | Operating Segments
Product Information [Line Items]
Net sales	$ 52,245	$ 109,202	$ 157,172	$ 337,005