Product Support Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Product Liability Contingency [Line Items]
Warranty Reserves	$ 440.0	$ 380.2
Deferred Revenues	801.4	699.9
Truck, Parts and Other
Product Liability Contingency [Line Items]
Warranty Reserves	440.0	380.2	$ 298.8	$ 282.1
Truck, Parts and Other | Accounts payable, accrued expenses and other
Product Liability Contingency [Line Items]
Warranty Reserves	270.6	233.0
Deferred Revenues	237.5	213.7
Truck, Parts and Other | Other liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	169.4	147.2
Deferred Revenues	547.6	468.8
Financial Services | Deferred Taxes and Other Liabilities
Product Liability Contingency [Line Items]
Deferred Revenues	$ 16.3	$ 17.4