Pre-Tax Effects of Gain (Loss) on Cash Flow Hedges Recognized in OCI (Detail) - Derivative Contracts - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Interest-Rate Contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	$ (42.3)	$ 19.9
Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	(21.1)	(28.9)
Truck, Parts and Other | Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	(20.1)	(28.4)
Financial Services | Interest-Rate Contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	(42.3)	19.9
Financial Services | Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	$ (1.0)	$ (0.5)