Product Support Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Product Liability Contingency [Line Items]
Warranty Reserves	$ 282.1	$ 346.2	$ 310.8	$ 218.7
Deferred Revenues	573.5	524.8	$ 462.0	$ 411.8
Truck, Parts and Other | Accounts payable, accrued expenses and other
Product Liability Contingency [Line Items]
Warranty Reserves	181.4	241.6
Deferred Revenues	162.8	142.5
Truck, Parts and Other | Other liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	100.7	104.6
Deferred Revenues	395.7	368.2
Financial Services | Deferred Taxes And Other Liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	0.0	0.0
Deferred Revenues	$ 15.0	$ 14.1