Major Product Categories and Percentage of Consolidated Net Sales (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Product Information [Line Items]
Net external sales	$ 491,697	$ 439,977	$ 1,335,838	$ 1,177,332
Percentage of consolidated net sales	100.00%	100.00%	100.00%	100.00%
Commercial Trailer Products
Product Information [Line Items]
Net external sales	333,873	276,564	859,867	704,712
Diversified Products
Product Information [Line Items]
Net external sales	112,860	117,990	334,281	338,937
Retail
Product Information [Line Items]
Net external sales	44,964	45,423	141,690	133,683
New Trailers
Product Information [Line Items]
Net external sales	401,069	339,914	1,053,769	882,325
Percentage of consolidated net sales	81.60%	77.30%	78.90%	74.90%
New Trailers | Commercial Trailer Products
Product Information [Line Items]
Net external sales	326,679	263,018	825,859	670,869
New Trailers | Diversified Products
Product Information [Line Items]
Net external sales	53,689	55,997	162,627	150,750
New Trailers | Retail
Product Information [Line Items]
Net external sales	20,701	20,899	65,283	60,706
Used Trailers
Product Information [Line Items]
Net external sales	7,028	13,326	38,103	32,566
Percentage of consolidated net sales	1.40%	3.00%	2.90%	2.80%
Used Trailers | Commercial Trailer Products
Product Information [Line Items]
Net external sales	1,956	9,092	21,788	20,407
Used Trailers | Diversified Products
Product Information [Line Items]
Net external sales	908	792	3,345	2,412
Used Trailers | Retail
Product Information [Line Items]
Net external sales	4,164	3,442	12,970	9,747
Components, parts and service
Product Information [Line Items]
Net external sales	40,981	47,924	134,517	142,113
Percentage of consolidated net sales	8.30%	10.90%	10.10%	12.10%
Components, parts and service | Commercial Trailer Products
Product Information [Line Items]
Net external sales	817	1,175	2,085	6,576
Components, parts and service | Diversified Products
Product Information [Line Items]
Net external sales	20,936	26,648	71,564	75,962
Components, parts and service | Retail
Product Information [Line Items]
Net external sales	19,228	20,101	60,868	59,575
Equipment and other
Product Information [Line Items]
Net external sales	42,619	38,813	109,449	120,328
Percentage of consolidated net sales	8.70%	8.80%	8.10%	10.20%
Equipment and other | Commercial Trailer Products
Product Information [Line Items]
Net external sales	4,421	3,279	10,135	6,860
Equipment and other | Diversified Products
Product Information [Line Items]
Net external sales	37,327	34,553	96,745	109,813
Equipment and other | Retail
Product Information [Line Items]
Net external sales	$ 871	$ 981	$ 2,569	$ 3,655