Significant Portion of Consolidated Revenues (Detail) (Sales Revenue, Net, Customer Concentration Risk)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
A.B. Volvo
Concentration Risk [Line Items]
Concentration Risk, Percentage	16.00%	15.00%	14.00%
Paccar
Concentration Risk [Line Items]
Concentration Risk, Percentage	16.00%	19.00%	18.00%
Daimler Trucks
Concentration Risk [Line Items]
Concentration Risk, Percentage	14.00%	15.00%	13.00%
Caterpillar
Concentration Risk [Line Items]
Concentration Risk, Percentage	7.00%	10.00%	11.00%
Navistar
Concentration Risk [Line Items]
Concentration Risk, Percentage	7.00%	7.00%	9.00%
Deere And Co
Concentration Risk [Line Items]
Concentration Risk, Percentage	5.00%	5.00%	4.00%