Finance Receivables - Summary of Loans by Risk Rate Grouping (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Mar. 31, 2026
Current Period
Total	$ 55,446		$ 54,876
Current Period, Gross charge-offs
Total	113	$ 102
Prior Year
Total	55,446		54,876
Prior Period, Gross charge-offs
Total	113	102
Dealer loans
Current Period
Total	4,696		4,703
Current Period, Gross charge-offs
Total	0	0
Prior Year
Total	4,696		4,703
Prior Period, Gross charge-offs
Total	0	$ 0
Performing \| Dealer loans
Current Period
Total	4,696		4,703
Current Period, Gross charge-offs
Total	0		0
Prior Year
Total	4,696		4,703
Prior Period, Gross charge-offs
Total	0		0
Performing \| Dealer loans \| Group I
Current Period
Total	3,285		3,290
Prior Year
Total	3,285		3,290
Performing \| Dealer loans \| Group II
Current Period
Total	1,411		1,413
Prior Year
Total	1,411		1,413
Performing \| Dealer loans \| Group III
Current Period
Total	0		0
Prior Year
Total	0		0
Performing \| Dealer loans \| Commercial loans
Current Period
2027	40		52
2026	46		148
2025	143		160
2024	131		52
2023	51		13
Prior	153		151
Revolving loans	1,070		991
Current Period, Gross charge-offs
2027	0		0
2026	0		0
2025	0		0
2024	0		0
2023	0		0
Prior	0		0
Revolving loans	0		0
Prior Year
2026	40		52
2025	46		148
2024	143		160
2023	131		52
2022	51		13
Prior	153		151
Revolving loans	1,070		991
Prior Period, Gross charge-offs
2026	0		0
2025	0		0
2024	0		0
2023	0		0
2022	0		0
Prior	0		0
Revolving loans	0		0
Performing \| Dealer loans \| Commercial loans \| Group I
Current Period
2027	39		50
2026	45		135
2025	130		104
2024	103		50
2023	49		8
Prior	123		125
Revolving loans	1,045		965
Prior Year
2026	39		50
2025	45		135
2024	130		104
2023	103		50
2022	49		8
Prior	123		125
Revolving loans	1,045		965
Performing \| Dealer loans \| Commercial loans \| Group II
Current Period
2027	1		2
2026	1		13
2025	13		56
2024	28		2
2023	2		5
Prior	30		26
Revolving loans	25		26
Prior Year
2026	1		2
2025	1		13
2024	13		56
2023	28		2
2022	2		5
Prior	30		26
Revolving loans	25		26
Performing \| Dealer loans \| Commercial loans \| Group III
Current Period
2027	0		0
2026	0		0
2025	0		0
2024	0		0
2023	0		0
Prior	0		0
Revolving loans	0		0
Prior Year
2026	0		0
2025	0		0
2024	0		0
2023	0		0
2022	0		0
Prior	0		0
Revolving loans	0		0
Performing \| Dealer loans \| Wholesale flooring
Current Period
Total	3,062		3,136
Current Period, Gross charge-offs
Total	0		0
Prior Year
Total	3,062		3,136
Prior Period, Gross charge-offs
Total	0		0
Performing \| Dealer loans \| Wholesale flooring \| Group I
Current Period
Total	1,751		1,853
Prior Year
Total	1,751		1,853
Performing \| Dealer loans \| Wholesale flooring \| Group II
Current Period
Total	1,311		1,283
Prior Year
Total	1,311		1,283
Performing \| Dealer loans \| Wholesale flooring \| Group III
Current Period
Total	0		0
Prior Year
Total	$ 0		$ 0

Current Period, Gross Write-Off

No definition available.

Name:	ahfc_CurrentPeriodGrossWriteOffAbstract
Namespace Prefix:	ahfc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Current Year

+ References

No definition available.

+ Details

Name:	ahfc_CurrentYearAbstract
Namespace Prefix:	ahfc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Prior Period, Gross Write-Off

+ References

No definition available.

+ Details

Name:	ahfc_PriorPeriodGrossWriteOffAbstract
Namespace Prefix:	ahfc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Prior Year

+ References

No definition available.

+ Details

Name:	ahfc_PriorYearAbstract
Namespace Prefix:	ahfc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolving
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ahfc_DealerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_PerformingFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=ahfc_GroupIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=ahfc_GroupIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=ahfc_GradeIIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ahfc_CommercialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ahfc_WholesaleFlooringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: