No definition available.

Name:	uhal_StatutoryFinancialInformationOfInsuranceSubsidiariesAbstract
Namespace Prefix:	uhal_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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

- Definition

Amount of dividends available for payment after computation of statutory restrictions on capital surplus.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Details

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

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=uhal_RepwestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=uhal_OxfordMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Statutory Financial Information of Insurance Subsidiaries (Narratives) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Property and Casualty Insurance [Member] \| Repwest [Member]
Statutory financial information of insurance subsidiaries:
Statutory accounting practices, statutory amount available for dividend payments		$ 22.7
Dividend payments restrictions schedule, amounts paid	$ 21.6
Restricted net assets, subsidiaries	$ 98.5		$ 130.2
Life Insurance [Member] \| Oxford [Member]
Statutory financial information of insurance subsidiaries:
Statutory accounting practices, statutory amount available for dividend payments		$ 18.6