Product Support Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Product Liability Contingency [Line Items]
Product Warranty Accrual	$ 630.5	$ 540.7	$ 448.7	$ 372.2
Truck, Parts and Other | Accounts Payable Accrued Expenses And Other Current Liabilities
Product Liability Contingency [Line Items]
Product Warranty Accrual	291.7	265.2
Truck, Parts and Other | Other Noncurrent Liabilities
Product Liability Contingency [Line Items]
Product Warranty Accrual	327.5	265.8
Financial Services | Deferred Taxes And Other Liabilities
Product Liability Contingency [Line Items]
Product Warranty Accrual	$ 11.3	$ 9.7