Pre-Tax Effects of Derivative Instruments Recognized in OCI (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest Rate Contract
Derivative [Line Items]
Loss (gain) recognized in OCI	$ 54.4	$ (27.9)	$ (55.2)
Expense (income) reclassified out of accumulated other comprehensive (loss) income into income	(36.0)	19.3	51.8
Interest Rate Contract | Financial Services
Derivative [Line Items]
Loss (gain) recognized in OCI	54.4	(27.9)	(55.2)
Interest Rate Contract | Financial Services | Interest and other borrowing expenses
Derivative [Line Items]
Expense (income) reclassified out of accumulated other comprehensive (loss) income into income	(36.0)	19.3	51.8
Foreign-exchange contracts
Derivative [Line Items]
Loss (gain) recognized in OCI	(1.2)	(1.3)	2.3
Expense (income) reclassified out of accumulated other comprehensive (loss) income into income	0.4	3.4	(4.1)
Foreign-exchange contracts | Truck, Parts and Other
Derivative [Line Items]
Loss (gain) recognized in OCI	(1.2)	(1.3)	2.3
Foreign-exchange contracts | Truck, Parts and Other | Cost of sales and revenues
Derivative [Line Items]
Expense (income) reclassified out of accumulated other comprehensive (loss) income into income	1.0	3.2	(4.1)
Foreign-exchange contracts | Truck, Parts and Other | Interest and other (expense) income, net
Derivative [Line Items]
Expense (income) reclassified out of accumulated other comprehensive (loss) income into income	$ (0.6)	$ 0.2