Major Product Categories and Percentage of Consolidated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Product Information [Line Items]
Net external sales	$ 514,831	$ 486,021	$ 952,428	$ 844,141
Percentage of consolidated net sales	100.00%	100.00%	100.00%	100.00%
Commercial Trailer Products
Product Information [Line Items]
Net external sales	$ 375,076	$ 319,287	$ 668,818	$ 526,785
Diversified Products
Product Information [Line Items]
Net external sales	94,516	115,367	195,557	220,630
Retail
Product Information [Line Items]
Net external sales	45,239	51,367	88,053	96,726
New Trailers
Product Information [Line Items]
Net external sales	$ 435,678	$ 384,582	$ 796,951	$ 652,700
Percentage of consolidated net sales	84.60%	79.10%	83.70%	77.30%
New Trailers | Commercial Trailer Products
Product Information [Line Items]
Net external sales	$ 365,325	$ 306,181	$ 652,746	$ 499,180
New Trailers | Diversified Products
Product Information [Line Items]
Net external sales	51,236	54,090	105,253	108,938
New Trailers | Retail
Product Information [Line Items]
Net external sales	19,117	24,311	38,952	44,582
Used Trailers
Product Information [Line Items]
Net external sales	$ 10,549	$ 15,010	$ 16,131	$ 31,075
Percentage of consolidated net sales	2.00%	3.10%	1.70%	3.70%
Used Trailers | Commercial Trailer Products
Product Information [Line Items]
Net external sales	$ 4,931	$ 8,584	$ 6,774	$ 19,832
Used Trailers | Diversified Products
Product Information [Line Items]
Net external sales	1,323	1,259	2,491	2,437
Used Trailers | Retail
Product Information [Line Items]
Net external sales	4,295	5,167	6,866	8,806
Components, parts and service
Product Information [Line Items]
Net external sales	$ 43,200	$ 51,838	$ 85,016	$ 93,536
Percentage of consolidated net sales	8.40%	10.70%	8.90%	11.10%
Components, parts and service | Commercial Trailer Products
Product Information [Line Items]
Net external sales	$ 1,548	$ 688	$ 2,813	$ 1,268
Components, parts and service | Diversified Products
Product Information [Line Items]
Net external sales	20,094	30,208	40,703	50,628
Components, parts and service | Retail
Product Information [Line Items]
Net external sales	21,558	20,942	41,500	41,640
Equipment and other
Product Information [Line Items]
Net external sales	$ 25,404	$ 34,591	$ 54,330	$ 66,830
Percentage of consolidated net sales	5.00%	7.10%	5.70%	7.90%
Equipment and other | Commercial Trailer Products
Product Information [Line Items]
Net external sales	$ 3,272	$ 3,834	$ 6,485	$ 6,505
Equipment and other | Diversified Products
Product Information [Line Items]
Net external sales	21,863	29,810	47,110	58,627
Equipment and other | Retail
Product Information [Line Items]
Net external sales	$ 269	$ 947	$ 735	$ 1,698