Amount of (Gain) Loss from Derivative Financial Instruments Recorded in Consolidated Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Interest-Rate Contracts
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	$ (40.1)	$ 35.3	$ (61.8)	$ 64.3
Interest-Rate Contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(40.1)	35.3	(61.8)	64.3
Foreign-exchange contracts
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(26.6)	24.9	(28.9)	26.1
Foreign-exchange contracts | Truck, Parts and Other
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(26.2)	26.6	(26.1)	25.7
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	(7.6)	(2.0)	(7.5)	(4.0)
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	(0.6)	3.0	0.2	4.9
Foreign-exchange contracts | Financial Services | Interest and other borrowing expenses
Derivative Instruments Gain Loss [Line Items]
Derivatives designated as hedging instruments (gain) loss	(0.4)	(1.7)	(2.8)	0.4
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	2.4	0.2	2.2	(0.1)
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	(42.4)	32.6	(66.9)	60.0
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	0.4	11.8	9.2	12.0
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	(17.5)	11.4	(24.9)	11.4
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	1.2	4.4	2.5	6.2
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	(2.8)	(1.9)	(5.0)	0.5
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	(2.1)	(2.0)	(5.6)	(4.8)
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	$ 2.3	$ 2.7	$ 5.1	$ 4.3