Accounting Policies (Policy Text Block)	12 Months Ended
	Mar. 31, 2022
Policy Text Block [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with the generally accepted accounting principles (“GAAP”) in the United States requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The accounting policies that we deem most critical to us and that require management’s most difficult and subjective judgments include the principles of consolidation, the recoverability of property, plant and equipment, the adequacy of insurance reserves, the recognition and measurement of impairments for investments accounted for under ASC 320 - Investments - Debt and Equity Securities and the recognition and measurement of income tax assets and liabilities. The actual results experienced by us may materially differ from management’s estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider cash equivalents to be highly liquid debt securities with insignificant interest rate risk with original maturities from the date of purchase of three months or less. Financial instruments that potentially subject us to concentrations of credit risk consist principally of cash deposits. Accounts at each United States financial institution are insured by the Federal Deposit Insurance Corporation up to $ 250,000 . Accounts at each Canadian financial institution are insured by the Canada Deposit Insurance Corporation up to $ 100,000 CAD per account. As of March 31, 2022 and March 31, 2021, we held cash equivalents in excess of these insured limits. To mitigate this risk, we select financial institutions based on their credit ratings and financial strength.
Investments	Investments Fixed Maturities and Marketable Equities. Fixed maturity investments consist of either marketable debt, equity or redeemable preferred stocks. As of the balance sheet dates, all of our investments in these securities were classified as available-for-sale. Available-for-sale investments are reported at fair value, with unrealized gains or losses recorded net of taxes and applicable adjustments to deferred policy acquisition costs in stockholders’ equity.  We adopted ASC Topic 326, Financial Instruments Credit Losses (“Topic 326”) as of April 1, 2020, for available-for-sale debt securities. This new standard requires the use of forward-looking information to estimate credit losses and requires credit losses for available for sale debt securities to be recorded through an allowance for credit losses rather than a reduction in the amortized cost basis.  Changes in the market value of common stocks are recognized in earnings. Fair   value for these investments is based on quoted market prices, dealer quotes or discounted cash flows. The cost of investments sold is based on the specific identification method. See Note 23, Allowance for Credit Losses, of the Notes to Consolidated Financial Statements. Mortgage Loans and Notes on Real Estate. Mortgage loans and notes on real estate are reported at their unpaid balance, net of any allowance for expected losses and any unamortized premium or discount. See Note 23, Allowance for Credit Losses, of the Notes to Consolidated Financial Statements. Recognition of Investment Income. Interest income from bonds and mortgage notes is recognized when earned. Dividends on common and preferred stocks are recognized on the ex-dividend dates. Realized gains and losses on the sale or exchange of investments are recognized at the trade date.
Derivative Financial Instruments	Accrued Interest Receivable Accrued interest receivables on available-for-sale securities totaled $28.7 million as of December 31, 2021 and are excluded from the estimate of credit losses. We have elected not to measure an allowance on accrued interest receivables as our practice is to write off the uncollectible balance in a timely manner. Furthermore, we have elected to write off accrued interest receivables by reversing interest income. Derivative Financial Instruments Our objective for holding derivative financial instruments is to manage interest rate risk exposure primarily through entering interest rate swap agreements and call options. We do not enter into these instruments for trading purposes. Counterparties to the interest rate swap agreements are major financial institutions. Derivatives are recognized at fair value on the balance sheet and are classified as prepaid expenses (asset) or accrued expenses (liability). Derivatives that are not designated as cash flow hedges for accounting purposes must be adjusted to fair value through income. If the derivative qualifies and is designated as a cash flow hedge, changes in its fair value will be recorded in accumulated other comprehensive income (loss) until the hedged item is recognized in earnings. See Note 10, Derivatives, of the Notes to Consolidated Financial Statements.
Inventory, net	Inventories and parts, net Inventories and parts, net were as follows:       March 31,     2022   2021     (In thousands) Truck and trailer parts and accessories (a) $ 148,237 $ 95,976 Hitches and towing components (b)   32,508   19,972 Moving supplies and propane (b)   16,623   12,877 Subtotal   197,368   128,825 Less: LIFO reserves   (37,400)   (21,832) Less: excess and obsolete reserves   (1,080)   (1,416) Total $ 158,888 $ 105,577           (a) Primarily held for internal usage, including equipment manufacturing and repair (b) Primarily held for retail sales           Inventories consist primarily of truck and trailer parts and accessories used to manufacture and repair rental equipment as well as products and accessories available for retail sale. Inventory is held at our owned locations; our independent dealers do not hold any of our inventory. Inventories are stated at the lower cost or net realizable value. Inventory cost is primarily determined using the last-in first-out method (“LIFO”). Inventories valued using LIFO consisted of approximately 93 % and 96 % of the total inventories for March 31, 2022 and 2021, respectively. Had we utilized the first-in first-out method (“FIFO”), stated inventory balances would have been $ 37.4 million and $ 21.8 million higher as of March 31, 2022 and 2021, respectively. In fiscal 2022, the negative effect on income due to liquidation of a portion of the LIFO inventory was $ 0.1 million.
Property, Plant and Equipment	Property, Plant and Equipment Our Property, plant and equipment is stated at cost. Interest expense, if any, incurred during the initial construction of buildings is considered part of cost. Depreciation is computed for financial reporting purposes using the straight line or an accelerated method based on a declining balance formula over the following estimated useful lives: rental equipment 2-20 years and buildings and non-rental equipment 3-55 years. Routine maintenance costs are charged to operating expense as they are incurred. Gains and losses on dispositions of property, plant and equipment, other than real estate (“personal property”), are netted against depreciation expense when realized. The net amount of gains, netted against depreciation expense, were $ 214.2 million, $ 54.1 million and $ 27.1 million during fiscal 2022, 2021 and 2020, respectively. Equipment depreciation is recognized in amounts expected to result in the recovery of estimated residual values upon disposal, i.e., minimize gains or losses. In determining the depreciation rate, historical disposal experience, holding periods and trends in the market for vehicles are reviewed. As a result of changes in Internal Revenue Service (“IRS”) regulations regarding the capitalization of assets, beginning in the first quarter of fiscal 2017, we raised the value threshold before certain assets are capitalized within our depreciation policy. This change in threshold, results in the immediate recognition of reported operating costs with a lagging decrease in depreciation expense over the term that these assets would have been depreciated. Due to this change, we had operating expenses of $ 28.7 million, $ 22.8 million and $ 26.9 million in fiscal 2022, 2021 and 2020, respectively. This change in threshold benefited us through the immediate recognition of tax deductible costs. We regularly perform reviews to determine whether facts and circumstances exist which indicate that the carrying amount of assets, including estimates of residual value, may not be recoverable or that the useful life of assets are shorter or longer than originally estimated. Reductions in residual values (i.e., the price at which we ultimately expect to dispose of revenue earning equipment) or useful lives will result in an increase in depreciation expense over the remaining life of the equipment. Reviews are performed based on vehicle class, generally subcategories of trucks and trailers. We assess the recoverability of our assets by comparing the projected undiscounted net cash flows associated with the related asset or group of assets over their estimated remaining lives against their respective carrying amounts. We consider factors such as current and expected future market price trends on used vehicles and the expected life of vehicles included in the fleet. Impairment, if any, is based on the excess of the carrying amount over the fair value of those assets. If asset residual values are determined to be recoverable, but the useful lives are shorter or longer than originally estimated, the net book value of the assets is depreciated over the newly determined remaining useful lives. For our box truck fleet we utilize an accelerated method of depreciation based upon a declining formula. Under the declining balances method (2.4 times declining balance), the book value of a rental truck is reduced approximately 16 %, 13 %, 11 %, 9 %, 8 %, 7 %, and 6 % during years one through seven, respectively and then reduced on a straight line basis to a salvage value of 15 % by the end of year fifteen. Comparatively, a standard straight line approach would reduce the book value by approximately 5.7 % per year over the life of the truck. Although we intend to sell our used vehicles for prices approximating book value, the extent to which we realize a gain or loss on the sale of used vehicles is dependent upon various factors including, but not limited to, the general state of the used vehicle market, the age and condition of the vehicle at the time of its disposal and the depreciation rates with respect to the vehicle . We typically sell our used vehicles at our sales centers throughout the United States and Canada, on our website at uhaul.com/trucksales or by phone at 1-866-404-0355. Additionally, we sell a large portion of our pickup and cargo van fleet at automobile dealer auctions. In addition to our property, plant and equipment, we had real estate held for future development or use of $67.8 million and $68.8 million for fiscal 2022 and 2021, respectively and is included in Investments, other.
Receivables	Receivables Trade receivables include trade accounts from moving and self-storage customers and dealers, insurance premiums and amounts due from re-insurers, less management’s estimate of expected losses. Moving and Storage has two (2) primary components of trade receivables, receivables from corporate customers and credit card receivables from sales and rentals of equipment.   For credit card receivables, the Company uses a trailing 13 months average historical chargeback percentage of total credit card receivables. The Company rents equipment to corporate customers in which payment terms are 30 days. The Company performs ongoing credit evaluations of its customers and assesses each customer’s credit worthiness. In addition, the Company monitors collections and payments from its customers and maintains an allowance based upon applying an expected credit loss rate to receivables based on the historical loss rate from similar high risk customers adjusted for current conditions, including any specific customer collection issues identified, and forecasts of economic conditions. Delinquent account balances are written off after management has determined that the likelihood of collection is remote. Management believes that the historical loss information it has compiled is a reasonable base on which to determine expected credit losses for trade receivables because the composition of trade receivables as of that date is consistent with that used in developing the historical credit-loss percentages (i.e., the similar risk characteristics of its customers and its lending practices have not changed significantly over time). To adjust the historical loss rates to reflect the effects of these differences in current conditions and forecasted changes, management assigns a rating to each customer which varies depending on the assessment of risk.   Management estimated the loss rate at approximately 6%. Management developed this estimate based on its knowledge of past experience. As a result, management applied the applicable credit loss rates to determine the expected credit loss estimate for each aging category. Insurance premiums receivable for policies that are billed through contracted agents are recorded net of commissions payable. A commission payable is recorded as a separate liability for those premiums that are billed direct. Reinsurance recoverables include case reserves and actuarial estimates of claims incurred but not reported ("IBNR"). These receivables are not expected to be collected until after the associated claim has been adjudicated and billed to the re-insurer. The reinsurance recoverables may have little or no allowance for credit losses due to the fact that reinsurance is typically procured from carriers with strong credit ratings. Furthermore, we do not cede losses to a re-insurer if the carrier is deemed financially unable to perform on the contract. Reinsurance recoverables also include insurance ceded to other insurance companies. The allowance for expected credit losses on trade receivables as of March 31, 2022 was $8.6 million. Notes and mortgage receivables include accrued interest and are reduced by discounts and amounts considered by management to be uncollectible.
Policy Benefits and Losses, Claims and Loss Expenses Payable	Policy Benefits and Losses, Claims and Loss Expenses Payable Liabilities for future policy benefits related to life insurance, Medical supplement insurance, and deferred annuities are determined by management utilizing the net premium valuation methodology and are accrued when premium revenue is recognized. The liability, which represents the present value of future benefits to be paid to policyholders and related expenses less the present value of future net premiums, is estimated using assumptions applicable at the time the insurance contracts are written, with provisions for the risk of adverse deviation, as appropriate. Assumptions include expected mortality and morbidity experience, policy lapses and surrenders, current asset yields and expenses, and expected interest rate yields. The Company periodically performs a gross premium valuation and reviews original assumptions, including capitalized expenses which reduce the gross premium valuation, to evaluate whether the assets and liabilities are adequate and whether a loss reserve should be recognized. Liabilities for health, disability and other policies include estimates of payments to be made on insurance claims for reported losses and estimates of IBNR losses. Oxford’s liabilities for deferred annuity contracts consist of contract account balances that accrue to the benefit of the policyholders. Property and Casualty Insurance’s liability for reported and unreported losses is based on Repwest’s historical data along with industry averages. The liability for unpaid loss adjustment expenses is based on historical ratios of loss adjustment expenses paid to losses paid. Amounts recoverable from re-insurers on unpaid losses are estimated in a manner consistent with the claim liability associated with the re-insured policy. Adjustments to the liability for unpaid losses and loss expenses as well as amounts recoverable from re-insurers on unpaid losses are charged or credited to expense in the periods in which they are made. Due to the nature of the underlying risks and high degree of uncertainty associated with the determination of the liability for future policy benefits and claims, the amounts to be ultimately paid to settle these liabilities cannot be precisely determined and may vary significantly from the estimated liability, especially for long-tailed casualty lines of business such as excess workers’ compensation.   As a result of the long-tailed nature of the excess workers’ compensation policies written by Repwest during 1983 through 2001, it may take a number of years for claims to be fully reported and finally settled. On a regular basis insurance reserve adequacy is reviewed by management to determine if existing assumptions need to be updated. In determining the assumptions for calculating workers’ compensation reserves, management considers multiple factors including the following:   Claimant longevity Cost trends associated with claimant treatments Changes in ceding entity and third party administrator reporting practices Changes in environmental factors including legal and regulatory Current conditions affecting claim settlements Future economic conditions including inflation We have reserved each claim based upon the accumulation of current claim costs projected through each claimant’s life expectancy and then adjusted for applicable reinsurance arrangements.   Management reviews each claim bi-annually or more frequently, if there are changes in facts or circumstances to determine if the estimated life-time claim costs have increased and then adjusts the reserve estimate accordingly at that time.   We have factored in an estimate of what the potential cost increases could be in our IBNR liability.   We have not assumed settlement of the existing claims in calculating the reserve amount, unless it is in the final stages of completion. Continued increases in claim costs, including medical inflation and new treatments and medications could lead to future adverse development resulting in additional reserve strengthening.   Conversely, settlement of existing claims or if injured workers return to work or expire prematurely, could lead to future positive development.
Self-Insurance Reserves	Self-Insurance Reserves U-Haul retains the risk for certain public liability and property damage programs related to our rental equipment. The consolidated balance sheets include $ 418.9 million and $ 427.1 million of liabilities related to these programs as of March 31, 2022 and 2021, respectively. These liabilities are recorded in Policy benefits and losses, claims and loss expenses payable. Management takes into account losses incurred based upon actuarial estimates, past experience, current claim trends, as well as social and economic conditions. This liability is subject to change in the future based upon changes in the underlying assumptions including claims experience, frequency of incidents, and severity of incidents. Additionally, as of March 31, 2022 and 2021, the consolidated balance sheets include liabilities of $ 19.7 million and $ 17.5 million, respectively, related to medical plan benefits we provide for eligible employees. We estimate this liability based on actual claims outstanding as of the balance sheet date as well as an actuarial estimate of IBNR claims. These amounts are recorded in Accounts payable and accrued expenses on the consolidated balance sheets.
Revenue Recognition	Revenue Recognition Self-moving rentals are recognized for the period that trucks and moving equipment are rented. Self-storage revenues, based upon the number of paid storage contract days, are recognized as earned during the period.   Sales of self-moving and self-storage related products are recognized at the time that title passes and the customer accepts delivery. Property and casualty insurance premiums are recognized as revenue over the policy periods. Traditional life and Medicare supplement insurance premiums are recognized as revenue over the premium-paying periods of the contracts when due from the policyholders. For products where premiums are due over a significantly shorter duration than the period over which benefits are provided, such as our single premium whole life product, premiums are recognized when received and excess profits are deferred and recognized in relation to the insurance in force. Interest and investment income are recognized as earned. Amounts collected from customers for sales tax are recorded on a net basis. Please see Note 22, Revenue Recognition, of the Notes to Consolidated Financial Statements.
Advertising	Advertising All advertising costs are expensed as incurred. Advertising expense was $ 13.7 million, $ 18.0 million and $ 13.7 million in fiscal 2022, 2021 and 2020, respectively.
Deferred Policy Acquisition Cost	Deferred Policy Acquisition Costs Commissions and other costs that fluctuate with and are primarily related to the successful acquisition or renewal of certain insurance premiums are deferred. For our Life Insurance’s life and health insurance products, these costs are amortized, with interest, in relation to revenue such that costs are realized as a constant percentage of revenue. For its annuity insurance products the costs are amortized, with interest, in relation to the present value of actual and expected gross profits. Starting in fiscal 2014, new annuity contract holders were provided with a sales inducement in the form of a premium bonus (the “Sales Inducement Asset”).   Sales inducements are recognized as an asset with a corresponding increase to the policyholder liability and are amortized in a similar manner to Deferred Policy Acquisition Costs.   As of December 31, 2021 and 2020, the Sales Inducement Asset included with Deferred Policy Acquisition Costs amounted to $ 15.7 million and $ 16.0 million, respectively on the consolidated balance sheet and amortization expense totaled $ 4.7 million, $ 4.3 million and $ 5.5 million for the periods ended December 31, 2021, 2020 and 2019, respectively.
Environmental Costs	Environmental Costs Liabilities are recorded when environmental assessments and remedial efforts, if applicable, are probable and the costs can be reasonably estimated. The amount of the liability is based on management’s best estimate of undiscounted future costs. Certain recoverable environmental costs related to the removal of underground storage tanks or related contamination are capitalized and amortized over the estimated useful lives of the properties. These costs are capitalized if they improve the safety or efficiency of the property or are incurred in preparing the property for sale.
Income Taxes	Income Taxes AMERCO files a consolidated tax return with all of its legal subsidiaries. The provision for income taxes reflects deferred income taxes resulting from changes in temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements. Deferred tax assets and liabilities represent the future tax consequence for those differences, which will either be taxable or deductible when the assets and liabilities are recovered or settled. Deferred taxes are also recognized for operating losses that are available to offset future taxable income. Valuation allowances are established when it is more likely than not that the deferred tax assets will not be realized.
Comprehensive Income (Loss)	Earnings Per Share Our earnings per share is calculated by dividing our earnings available to common stockholders by the weighted average common shares outstanding, basic and diluted. The weighted average common shares outstanding exclude post-1992 shares of the employee stock ownership plan that have not been committed to be released.   As of March 31, 2022 and 2021 all of these shares have been released. There are no dilutive securities for fiscal years 2022, 2021 and 2020. Comprehensive Income (Loss) Comprehensive income (loss) consists of net earnings, foreign currency translation adjustments, unrealized gains and losses on investments, the change in fair value of cash flow hedges and the change in postretirement benefit obligations.
Debt issuance costs	Debt Issuance Costs We defer costs directly associated with acquiring third-party financing. Debt issuance costs are deferred and amortized to interest expense using the effective interest method. Debt issuance costs related to our long-term debt are reflected as a direct deduction from the carrying amount of the debt. Please see Note 8, Borrowings, of the Notes to Consolidated Financial Statements.
Adoption of New Accounting Pronouncements	Adoption of New Accounting Pronouncements On April 1, 2021, we adopted ASU 2020-08, Clarifying Guidance on Amortization of the Excess of the Cost Basis of Certain Callable Debt Securities Over the Amount Repayable.   This standard requires that, for each reporting period, callable debt securities be reevaluated to determine if they remain subject to the guidance, which will depend on the amortized cost basis of the security and the terms of the next call option.   The guidance is effective for fiscal years beginning after December 15, 2020. The adoption of the standard did not have a material impact on our consolidated financial statements. On April 1, 2021, we adopted, ASU 2020-04, Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”). This standard provides temporary optional expedients and exceptions to the US GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens of the expected market transition from the London Inter-Bank Offer Rate (“LIBOR”) and other interbank offered rates to alternative reference rates, such as Secured Overnight Financing Rate. Entities can elect not to apply certain modification accounting requirements to contracts affected by what the guidance calls reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. The guidance is effective upon issuance and generally can be applied through December 31, 2022. We adopted this standard and there was no impact to our consolidated financial statements. In January 2021, FASB issued ASU 2021-01, Reference Rate Reform (Topic 848), (“ASU 2021-01”).   The amendments in ASU 2021-01 provide optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued because of the reference rate reform.   We adopted ASU 2021-01 on a prospective basis effect and there was no impact to our consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued ASU 2018-12, Targeted Improvements to the Accounting for Long-Duration Contracts (“ASU 2018-12”). The amendments in this update require insurance companies to annually review and update the assumptions used for measuring the liability under long-duration contracts, such as life insurance, disability income, and annuities. The amendment prescribes standardized liability discount rate, consistency in measurement of market risk benefits, simplified amortization of deferred acquisition costs and enhanced disclosures. The amendments are effective for fiscal years, and interim periods within those fiscal years, beginning after December 31, 2020. In November 2020, FASB issued ASU 2020-11, Financial Services – Insurance (Topic 944) , which deferred the effective date of ASU 2018-12 to years beginning after December 15, 2022. We are currently in the process of evaluating the impact of the adoption of ASU 2018-12 on our financial statements; however, the adoption of ASU 2018-12 will impact the statements of operations because the effect of any update to the assumptions we used at the inception of the contracts will be recorded in net income. From time to time, new accounting pronouncements are issued by the FASB or the Securities and Exchange Commission (“SEC”) that are adopted by us as of the specified effective date. Unless otherwise discussed, these ASUs entail technical corrections to existing guidance or affect guidance related to specialized industries or entities and therefore will have minimal, if any, impact on our financial position or results of operations upon adoption.