Borrowings (Long-term Debt Borrowings) (Details) - USD ($) $ in Thousands	9 Months Ended
Dec. 31, 2016	Mar. 31, 2016
Debt instrument, maturities:
Notes, loans and leases payable, gross	$ 3,223,189	$ 2,688,758
Less: Debt issuance costs	(24,754)	(23,362)
Total notes, loans and leases payable	$ 3,198,435	2,665,396
Real estate loan (amortizing term) [Member]
Debt instrument, maturities:
Debt instrument, maturity year	2023
Total notes, loans and leases payable	$ 171,789	205,000
Real estate loan (amortizing term) [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.17%
Real estate loan (amortizing term) [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	6.93%
Senior Mortgages [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2017
Debt instrument, maturity year range, end	2038
Total notes, loans and leases payable	$ 1,256,832	1,121,897
Senior Mortgages [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.24%
Senior Mortgages [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.50%
Working capital loan (revolving credit) [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.24%
Debt instrument, maturities:
Debt instrument, maturity year	2018
Total notes, loans and leases payable	$ 85,000
Fleet loans (amortization term) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2017
Debt instrument, maturity year range, end	2023
Total notes, loans and leases payable	$ 216,582	218,998
Fleet loans (amortization term) [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.95%
Fleet loans (amortization term) [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.76%
Fleet loans (securitization) [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.90%
Debt instrument, maturities:
Debt instrument, maturity year	2017
Total notes, loans and leases payable	$ 53,876	62,838
Fleet loans (revolving credit) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2018
Debt instrument, maturity year range, end	2021
Total notes, loans and leases payable	$ 454,000	347,000
Fleet loans (revolving credit) [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.76%
Fleet loans (revolving credit) [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.46%
Capital Leases (rental equipment) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2017
Debt instrument, maturity year range, end	2024
Total notes, loans and leases payable	$ 917,792	672,825
Capital Leases (rental equipment) [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.12%
Capital Leases (rental equipment) [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	7.16%
Other Obligations [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2017
Debt instrument, maturity year range, end	2045
Total notes, loans and leases payable	$ 67,318	$ 60,200
Other Obligations [Member] \| Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	3.00%
Other Obligations [Member] \| Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	8.00%

The latest maturity year for these debt instruments.

No definition available.

Name:	uhal_MaturityEndYear
Namespace Prefix:	uhal_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

The earliest maturity year for these debt instruments.

+ References

No definition available.

+ Details

Name:	uhal_MaturityStartYear
Namespace Prefix:	uhal_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

The DebtInstrumentMaturityDate could have worked for this element, but it must include the format Month-Date-Year. Will use this US-GAAP Element in the next few schedules, when possible, where we break down the various items that make up the Borrowing's narrative.

+ References

No definition available.

+ Details

Name:	uhal_MaturityYear
Namespace Prefix:	uhal_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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

- References

No definition available.

+ Details

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

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=uhal_FleetLoanSecuritizationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=uhal_FleetLoansRevolvingCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_CapitalLeaseObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: