Product Support Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Product Liability Contingency [Line Items]
Warranty Reserves	$ 346.2	$ 310.8	$ 218.7	$ 208.8
Deferred Revenues	524.8	462.0	$ 411.8	$ 331.9
Truck, Parts and Other | Accounts payable, accrued expenses and other
Product Liability Contingency [Line Items]
Warranty Reserves	241.6	229.1
Deferred Revenues	142.5	126.2
Truck, Parts and Other | Other liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	104.6	81.7
Deferred Revenues	368.2	324.5
Financial Services | Deferred Taxes And Other Liabilities
Product Liability Contingency [Line Items]
Deferred Revenues	$ 14.1	$ 11.3