Life Insurance Liabilities (Sensitive Life Insurance Type Products) (Details) - USD ($)	3 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Interest expense	$ 82,330,000	$ 67,218,000
Life Insurance Segment [Member] \| Oxford
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Gross premiums	11,967,000	12,538,000
Interest expense	$ 3,690,000	$ 3,786,000
Expected future lifetime (persistency) of policies in force (years)	6 years 8 months 12 days	6 years 9 months 18 days
Weighted average original interest rate of the liability for future policy benefits	4.91%	4.98%
Weighted average current interest rate of the liability for future policy benefits	4.53%	4.97%
Life Insurance Segment [Member] \| Oxford \| Expected gross premiums:
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Undiscounted balance	$ 332,228,000	$ 358,097,000
Discounted balance at original discount rate	256,950,000	278,118,000
Discounted balance at current discount rate	256,112,000	274,345,000
Life Insurance Segment [Member] \| Oxford \| Expected policy benefits:
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Undiscounted balance	692,712,000	732,006,000
Discounted balance at original discount rate	481,531,000	507,787,000
Discounted balance at current discount rate	$ 480,547,000	$ 503,456,000
Life Insurance Segment [Member] \| Oxford \| Lapses actual experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0699	0.0549
Life Insurance Segment [Member] \| Oxford \| Mortality expected experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.058	0.0535
Life Insurance Segment [Member] \| Oxford \| Lapses actual experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0217	0.0192
Life Insurance Segment [Member] \| Oxford \| Lapses expected experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0314	0.0273

Discounted balance at original discount rate, subsidiary.

No definition available.

Name:	uhal_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitDiscountedAtOriginalRate
Namespace Prefix:	uhal_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest expense classified as operating and nonoperating. Includes, but is not limited to, cost of borrowing accounted for as interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 49
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-49

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-24

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483013/835-20-50-1

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479105/946-220-45-3

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Current weighted-average discount rate used to measure liability for future policy benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(6)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit.

+ References

+ Details

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

- Definition

Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted-average duration of liability for future policy benefit, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(5)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Original weighted-average discount rate at contract issue date used to measure liability for future policy benefit.

+ References

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of measurement input used to measure contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_MarketRiskBenefitMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount before valuation allowance of reinsurance recoverables on paid losses.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479838/944-20-50-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 310
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477363/944-310-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477409/944-310-45-6

+ Details

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

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_LifeInsuranceSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_CorporateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputUtilizationRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=uhal_MeasurementInputActualMortalityRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputMortalityRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=uhal_MeasurementInputActualLapseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputLapseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: