ESOP Total Amount Contributed to the Plan Trust (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee stock ownership plan (ESOP), cash contributions to ESOP	$ 1.0	$ 0.7	$ 1.7
Unallocated common stock dividend, debt repayment	0.6
Cash contributions to ESOP, non leveraged	$ 8.0

This item represents the non leveraged amount of cash contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP).

No definition available.

+ Details

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Namespace Prefix:	uhal_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the amount of cash contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

+ Details

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

- Definition

The amount of cash provided by the employer through contributions or dividends that the ESOP used in the period to repay debt and interest on a third-party loan made directly to the ESOP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 25

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6418455&loc=d3e16545-113920

+ Details

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