Amount of Loss (Gain) from Derivative Financial Instruments Recorded in Consolidated Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Interest-Rate Contracts
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	$ (39.4)	$ (56.4)	$ 24.9	$ (99.4)
Interest-Rate Contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(39.4)	(56.4)	24.9	(99.4)
Foreign-exchange contracts
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	4.7	(7.2)	30.9	9.5
Foreign-exchange contracts | Truck, Parts and Other
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	4.8	(7.1)	30.6	14.0
Foreign-exchange contracts | Truck, Parts and Other | Cost of sales and revenues | Not designated as hedging instruments
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(0.4)	0.4	4.5	0.3
Foreign-exchange contracts | Truck, Parts and Other | Interest and other (income) expenses, net | Not designated as hedging instruments
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	0.7	(5.8)	0.6	(4.5)
Foreign-exchange contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(0.1)	(0.1)	0.3	(4.5)
Foreign-exchange contracts | Financial Services | Interest and other borrowing expenses | Not designated as hedging instruments
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	0.3	2.9	(3.7)	3.1
Cash Flow Hedging | Interest-Rate Contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(42.1)	(56.2)	17.9	(99.3)
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Net sales and revenues
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	13.2	2.0	25.2	17.1
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Cost of sales and revenues
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(9.6)	(6.2)	1.8	(3.5)
Cash Flow Hedging | Foreign-exchange contracts | Truck, Parts and Other | Interest and other (income) expenses, net
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	3.3	3.9	9.5	8.8
Cash Flow Hedging | Foreign-exchange contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(0.8)	(3.0)	(0.3)	(7.6)
Net Investment Hedging | Foreign-exchange contracts | Truck, Parts and Other | Interest and other (income) expenses, net
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(2.0)	(1.4)	(6.7)	(4.2)
Fair Value Hedging | Interest-Rate Contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	$ 2.7	$ (0.2)	$ 7.0	$ (0.1)