Major Product Categories and Percentage of Consolidated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Product Information [Line Items]
Total Net Sales	$ 471,438	$ 514,831	$ 919,114	$ 952,428
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	$ (3,644)	$ (3,139)	$ (6,297)	$ (5,871)
Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	382,212	412,664	746,252	741,853
Diversified Products
Product Information [Line Items]
Total Net Sales	92,870	105,306	179,159	216,446
New Trailers
Product Information [Line Items]
Total Net Sales	$ 393,992	$ 435,678	$ 765,801	$ 796,950
New Trailers \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	83.60%	84.60%	83.30%	83.70%
New Trailers \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ 0	$ 0	$ 0	$ 0
New Trailers \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	359,763	384,442	701,796	691,696
New Trailers \| Diversified Products
Product Information [Line Items]
Total Net Sales	34,229	51,236	64,005	105,254
Used Trailers
Product Information [Line Items]
Total Net Sales	$ 4,520	$ 10,549	$ 9,273	$ 16,132
Used Trailers \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	1.00%	2.00%	1.00%	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	3,427	9,226	7,279	13,640
Used Trailers \| Diversified Products
Product Information [Line Items]
Total Net Sales	1,093	1,323	1,994	2,492
Components, parts and service
Product Information [Line Items]
Total Net Sales	$ 43,183	$ 43,200	$ 82,118	$ 84,713
Components, parts and service \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	9.20%	8.40%	8.90%	8.90%
Components, parts and service \| Corporate and Eliminations
Product Information [Line Items]
Total Net Sales	$ (3,644)	$ (3,139)	$ (6,297)	$ (5,823)
Components, parts and service \| Commercial Trailer Products
Product Information [Line Items]
Total Net Sales	14,869	15,616	29,070	29,619
Components, parts and service \| Diversified Products
Product Information [Line Items]
Total Net Sales	31,958	30,723	59,345	60,917
Equipment and other
Product Information [Line Items]
Total Net Sales	$ 29,743	$ 25,404	$ 61,922	$ 54,633
Equipment and other \| Sales Revenue, Net [Member]
Product Information [Line Items]
Percentage of consolidated net sales	6.20%	5.00%	6.80%	5.70%
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	4,153	3,380	8,107	6,898
Equipment and other \| Diversified Products
Product Information [Line Items]
Total Net Sales	$ 25,590	$ 22,024	$ 53,815	$ 47,783