Amount before tax and reclassification adjustments of other comprehensive income (loss).

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Namespace Prefix:	us-gaap_
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Period Type:	duration

Pre-Tax Effects of Gain (Loss) on Cash Flow Hedges Recognized in OCI (Detail) - Derivative Contracts - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Interest-Rate Contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	$ 49.4	$ 43.4	$ 109.1	$ 67.1
Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	35.3	2.9	35.1	(9.0)
Commodity Contract
Derivative [Line Items]
Gain (loss) recognized in OCI	(7.9)	(9.8)	(15.7)	(9.8)
Truck, Parts and Other \| Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	35.4	2.3	35.5	(6.7)
Truck, Parts and Other \| Commodity Contract
Derivative [Line Items]
Gain (loss) recognized in OCI	(7.9)	(9.8)	(15.7)	(9.8)
Financial Services \| Interest-Rate Contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	49.4	43.4	109.1	67.1
Financial Services \| Foreign-exchange contracts
Derivative [Line Items]
Gain (loss) recognized in OCI	$ (0.1)	$ 0.6	$ (0.4)	$ (2.3)