Net Investment and Interest Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Net Investment Income [Line Items]
Investment income	$ 75,858us-gaap_NetInvestmentIncome	$ 68,801us-gaap_NetInvestmentIncome	$ 70,521us-gaap_NetInvestmentIncome
Less: investment expenses	(1,962)	(1,629)	(1,374)
Investment income, related party	10,832uhal_InvestmentIncomeRelatedParty	12,419uhal_InvestmentIncomeRelatedParty	13,756uhal_InvestmentIncomeRelatedParty
Net investment and interest income	84,728	79,591	82,903
Fixed Maturities [Member]
Net Investment Income [Line Items]
Investment income	58,716	53,634	50,696
Real Estate [Member]
Net Investment Income [Line Items]
Investment income	2,669	1,118	380
Insurance policy loans [Member]
Net Investment Income [Line Items]
Investment income	1,072	1,159	1,126
Mortgage loans [Member]
Net Investment Income [Line Items]
Investment income	10,677	9,450	17,952
Short-term, amounts held by ceding reinsurers, net and other investments [Member]
Net Investment Income [Line Items]
Investment income	$ 2,724	$ 3,440	$ 367

Income derived from investments in related party.

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- Definition

Amount before accretion (amortization) of purchase discount (premium) of interest income and dividend income on nonoperating securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(a),(b))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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- Definition

Amount of expenses related to the generation of investment income.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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- Definition

Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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