Product Support Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Liability Contingency [Line Items]
Warranty Reserves	$ 344.3	$ 389.7
Deferred Revenues	775.2	795.8
Truck, Parts and Other
Product Liability Contingency [Line Items]
Warranty Reserves	344.3	389.7	$ 440.0	$ 380.2
Truck, Parts and Other | Accounts payable, accrued expenses and other
Product Liability Contingency [Line Items]
Warranty Reserves	215.5	245.6
Deferred Revenues	259.5	269.0
Truck, Parts and Other | Other liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	128.8	144.1
Deferred Revenues	503.2	513.1
Financial Services | Accounts payable, accrued expenses and other
Product Liability Contingency [Line Items]
Warranty Reserves	0.0	0.0
Deferred Revenues	4.6	5.7
Financial Services | Deferred Taxes and Other Liabilities
Product Liability Contingency [Line Items]
Warranty Reserves	0.0	0.0
Deferred Revenues	$ 7.9	$ 8.0