Major Product Categories and Percentage of Consolidated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Product Information [Line Items]
Total Net Sales	$ 464,272	$ 531,350	$ 1,383,387	$ 1,483,778
Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	100.00%	100.00%	100.00%	100.00%
Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ (3,692)	$ (2,847)	$ (9,989)	$ (8,718)
Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	380,514	406,410	1,126,767	1,148,263
Diversified Products
Product Information [Line Items]
Total Net Sales	87,450	127,787	266,609	344,233
New Trailers
Product Information [Line Items]
Total Net Sales	$ 392,214	$ 442,250	$ 1,158,015	$ 1,239,200
New Trailers \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	84.50%	83.20%	83.70%	83.50%
New Trailers \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ (89)	$ 0	$ (89)	$ 0
New Trailers \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	360,023	377,892	1,061,819	1,069,588
New Trailers \| Diversified Products
Product Information [Line Items]
Total Net Sales	32,280	64,358	96,285	169,612
Used Trailers
Product Information [Line Items]
Total Net Sales	$ 3,544	$ 9,362	$ 12,817	$ 25,494
Used Trailers \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	0.80%	1.80%	0.90%	1.70%
Used Trailers \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ 0	$ 0	$ 0	$ 0
Used Trailers \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	2,923	8,441	10,202	22,081
Used Trailers \| Diversified Products
Product Information [Line Items]
Total Net Sales	621	921	2,615	3,413
Components, parts and service
Product Information [Line Items]
Total Net Sales	$ 39,743	$ 45,935	$ 121,861	$ 130,648
Components, parts and service \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	8.60%	8.60%	8.80%	8.80%
Components, parts and service \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ (3,603)	$ (2,847)	$ (9,900)	$ (8,670)
Components, parts and service \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	14,038	16,067	43,108	45,686
Components, parts and service \| Diversified Products
Product Information [Line Items]
Total Net Sales	29,308	32,715	88,653	93,632
Equipment and other
Product Information [Line Items]
Total Net Sales	$ 28,771	$ 33,803	$ 90,694	$ 88,436
Equipment and other \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	6.10%	6.40%	6.60%	6.00%
Equipment and other \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ 0	$ 0	$ 0	$ (48)
Equipment and other \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	3,530	4,010	11,638	10,908
Equipment and other \| Diversified Products
Product Information [Line Items]
Total Net Sales	$ 25,241	$ 29,793	$ 79,056	$ 77,576