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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482765/220-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481674/830-30-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481694/830-30-45-17

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
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-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481694/830-30-45-20

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482765/220-10-50-4

Name:	us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Pre-Tax Effects of (Loss) Gain on Cash Flow Hedges Recognized in OCI (Detail) - Derivative Contracts - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Interest-Rate Contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	$ (39.4)	$ (124.1)	$ (78.3)	$ (196.1)
Foreign-exchange contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	(1.6)	(36.9)	(27.6)	(57.3)
Commodity contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	1.7	1.6	3.0	1.4
Truck, Parts and Other \| Foreign-exchange contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	1.3	(31.2)	(16.9)	(42.5)
Truck, Parts and Other \| Commodity contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	1.7	1.6	3.0	1.4
Financial Services \| Interest-Rate Contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	(39.4)	(124.1)	(78.3)	(196.1)
Financial Services \| Foreign-exchange contracts
Derivative [Line Items]
(Loss) gain recognized in OCI	$ (2.9)	$ (5.7)	$ (10.7)	$ (14.8)