CANADA [Member] Canada [Member] UNITED STATES [Member] United States [Member] Amendment Description Amendment Flag Current Fiscal Year End Date Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date Document Type Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity [Domain] AMERCO Consolidated Entity Filer Category Entity Public Float Entity Registrant Name Entity Voluntary Filers Entity Well-known Seasoned Issuer Legal Entity [Axis] A roll forward schedule of the summary of accumulated other comprehensive income (loss) components, net of tax. Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward] Amerco Common Stock [Member] U-Haul International, North America's largest "do-it-yourself" moving and storage operator. Amerco Real Estate and Uhaul Intl [Member] Amerco Real Estate and U-Haul Int'l Guarantor [Member] Subsidiary company associated with an asset-backed working capital loan. Amerco Real Estate Company [Member] Amerco Real Estate Company Affiliates of Amerco with outstanding Real Estate loans. Amerco Real Estate Subsidiaries and Uhaul Company of Florida [Member] Amerco Real Estate, Subsidiaries, and U-Haul Co. of Florida The Company and associates offering U-Notes secured by various types of collateral including rental equipment and real estate. Amerco, Us Bank, National Association, Trustee [Member] Amerco and US Bank, National Association, the Trustee Fleet loan provision specified LIBOR plus applicable margin. This is the highest of the two applicable margin rates at the time of the loan agreement. Applicable Margin, Per Loan Agreement, Maximum Rate Applicable margin, per loan agreement, maximum rate Fleet loan provision specified LIBOR plus applicable margin. This is the lower of the two applicable margin rates at the time of the loan agreement. Applicable Margin, Per Loan Agreement, Minimum Rate Applicable margin, per loan agreement, minimum rate Sum of LIBOR and margin, at the higher of the rate. Applicable Margins, High Rate Sum of LIBOR and margin, maximum rate This is the sum of LIBOR and margin, at the lower of the rate range. Applicable Margins, Low Rate Sum of LIBOR and margin, minimum rate Amount of accumulated unrealized loss on investments in debt and/or equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or less. Available For Sale Investments Continuous Unrealized Loss Position Less Than Twelve Months Fair Value Gross unrealized losses less than 12 months This item represents the aggregate fair value of investments in debt and/or equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. Available For Sale Investments Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value Gross unrealized losses more than 12 months A subsidiary of U-Haul International has a term loan funding cargo van and pickup acquisitions. Cargo Van and Pickup Acquisitions [Member] Cargo Van and Pickup Acquisitions Cash generated from agreements and notes with SAC Holdings, Four SAC, Five SAC, Galaxy and Private Mini, excluding Dealer Agreements. Cash Generated from Agreements and Notes Cash flow, related party Fair value of common stock at quoted prices in active markets. Common Stock, Fair Value Disclosure Common stock Listed separately the common and preferred stock shares and amounts in treasury. Common Stock in Treasury [Member] Cost of common shares in treasury, net (22,377,912 shares as of June 30 and March 31, 2013) Cost of common shares in treasury, net The debt agreement amount at the beginning of this contract. It is no longer valid because of a subsequent amendment in the terms of this loan. Debt Instrument, Original Face Amount Debt instrument, original face amount This company-specific concept is a combination of three us-gaap taxonomy concepts. (1) Depreciation: "The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation." (2) Gain (Loss) on Disposition of Assets: "The gains and losses included in earnings resulting from the sale or disposal of tangible assets." (3) Deferred Policy Acquisition Cost Amortization Expense: "Amount of deferred policy acquisition costs charged to expense in the period, generally in proportion to related revenue earned, estimated gross profits, or over the customer relationship or some other period." Depreciation and Amortization, Net of (Gains) Losses on Disposals Depreciation and amortization, net of (gains) losses on disposals Depreciation and amortization, net of (gains) losses on disposals This company-specific concept is a combination of two US-GAAP taxonomy concepts. (1) Depreciation: "The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation." (2) Gain (Loss) on Disposition of Assets: "The gains and losses included in earnings resulting from the sale or disposal of tangible assets." Depreciation, Net of Gains (Losses) on Disposals Depreciation, net of (gains) losses on disposals Depreciation, net of (gains) on disposals (($7,917) and ($8,921),respectively) The date the derivative agreement becomes effective. This date differs from the agreement date. Derivative Effective Date Effective date Date the derivative is designated as a cash flow hedge. Designated Cash Flow Hedge Date Designed cash flow hedge date Document and Entity Information [Abstract] The Company has not provided financial or other support explicitly or implicitly during the period ended to any of these entities that it was not previously contractually required to provide. The carrying amount and the classification of assets and liabilities in the Company's balance sheet that related to the Company's variable interest in the Blackwater's entities are noted here, which approximate the maximum exposure to loss as a result of the Company's involvement with these entities. Due from Related Party, Recap of Assets [Text Block] Related party assets The Segmented Cash Flow statement contains a breakout of earnings from consolidated entities. The Consolidated Cash Flow Statement does not contain this concept, but both of these groups (roles) use the same calculation, so need to include this concept in both groups (roles). Earnings from Consolidated Entities Earnings from consolidated entities Earnings from consolidated entities Effect of Interest Rate Contracts [Abstract] The effect of interest rate contracts on the statement of operations: U-Haul S Fleet and its subsidiaries (collectively, "USF") issued asset-backed notes ("2007 Box Truck Note") and ("2010 Box Truck Note"). USF is a bankruptcy-remote special purpose entity wholly-owned by U-Haul International, Inc. The net proceeds from the securitized transaction were used to finance new box truck purchases. U. S. Bank, NA acts as the trustee for this securitization. These notes have fixed interest rates. The notes are secured by the box trucks that were purchased and the corresponding operating cash flows associated with their operation. Fleet Loan Securitization [Member] Rental Truck (securitization) [Member] The revolver requires monthly interest payments only for the first four years and principal and interest payments due over the last nine months. The interest rates, per the provision of the revolving fleet loan are the applicable LIBOR plus a margin. Fleet Loans Revolving Credit [Member] Fleet loans (revolving credit) [Member] We used "AvailableForSaleSecuritiesGrossUnrealizedGainLoss" in prior filings for this concept, but the 2013 taxonomy deprecated the above concept and created a new one with the period type changed to 'duration.' We must have an 'instant' period type in order to complete the calculation within this schedule. This is the unrealized gain on all our available-for-sale investments as of the quarter ending date. Gross Unrealized Gains Gross unrealized gains We include two different LIBOR rates for these loans in our documentation. High Libor Rate LIBOR - highest rate This is a primary concept, which incorporates two US-GAAP concepts: (1) IncreaseDecreaseInReinsuranceRecoverable with the definition "the increase (decrease) during the reporting period in the amount of benefits the ceding insurer expects to recover on insurance policies ceded to other insurance entities as of the balance sheet date for all guaranteed benefit types." (2) IncreaseDecreaseInReceivables with the definition: "The increase (decrease) during the reporting period in the total amount due within one year (or one operating cycle) from all parties, associated with underlying transactions that are classified as operating activities." Increase Decrease In Reinsurance Recoverables Receivables Reinsurance recoverables and trade receivables This insurance grouping includes RepWest and Oxford Life Insurance. Insurance Group [Member] Insurance group Our disclosure provides for only the interest expense on borrowings. Within the US-GAAP taxonomy, there is an Interest Income and Interest Expense Disclosure [Text Block], but nothing that specifically covers only Interest Expense. Interest Expense Disclosure [Text Block] Interest expense disclosure Components of interest expense We provide the expiration year on our rental equipment, not the complete date. Lease expiration year Lease expiration year Date the counterclaim was filed by defendent. Loss Contingency Counterclaim Date Loss contingency counterclaim date The latest maturity year for these debt instruments. Maturity End Year Debt instrument, maturity year range, end The earliest maturity year for these debt instruments. Maturity Start Year Debt instrument, maturity year range, start 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. Maturity Year Debt instrument, maturity year Mercury Partners, L.P. ("Mercury") owns and leases self-storage properties. Mercury [Member] Mercury Moving and Storage operations includes AMERCO, U-Haul and Real Estate and the wholly-owned subsidiaries of U-Haul and Real Estate. Operations consist of the rental of trucks and trailers, sales of moving supplies, sales of towing accessories, sales of propane, the rental of self-storage spaces to the "do-it-yourself" mover and management of self-storage properties owned by others. Operations are conducted under the registered trade name U-Haul(R) throughout the United States and Canada. Moving and Storage Consolidations [Member] Moving and Storage Operating Segment Aggregate notional amount on operating lease derivatives, which relates to the currency amount specified on operating lease derivatives. Notional Amount on Operating Lease Derivatives Notional amount of operating lease List of other comprehensive income items not related to net earnings Other Comprehensive Income (Loss) [Abstract] Other comprehensive income (loss): Fair value of preferred stock at quoted prices in active markets. Preferred Stock, Fair Value Disclosure Preferred stock Listed separately the shares and values of common and preferred stock in treasury. Preferred Stock in Treasury [Member] Cost of preferred shares in treasury, net (6,100,000 shares as of June 30 and March 31, 2013) Cost of preferred shares in treasury, net Private Mini Storage Realty, L.P. (Private Mini") is ultimately controlled by Blackwater. Private Mini [Member] Private Mini The Property and Casualty Insurance operating segment includes RepWest and its wholly-owned subsidiaries and ARCOA risk retention group ("ARCOA"). Property and Casualty Insurance provides loss adjusting and claims handling for U-Haul through regional offices across North America. Property and Casualty Insurance also underwrites components of the Safemove, Safetow, Super Safemove and Safestor protection packages to U-Haul customers. The business plan for the Property and Casualty Insurance operating segment includes offering property and casualty products in other U-Haul related programs. ARCOA is a captive insurer owned by the Company whose purpose is to provide insurance products related to the moving and storage business. Property and Casualty Insurance [Member] Property and Casualty Insurance Quarter Ending [Abstract] Quarter ended: Reclassification of Aoci To Earnings [Abstract] This extended concept is a combination of two concepts on the US-GAAP taxonomy. (1) Reinsurance Recoverables defined as..."The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance." (2) Receivables, Net, Current defined as..."The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowance established for the purpose of reducing such receivables to an amount that approximates their net realizable value" Reinsurance Recoverables and Trade Receivables, Net Reinsurance recoverables and trade receivables, net Related Party Cost and Expense [Abstract] Related party cost and expense: Related Party Notes Receivable [Abstract] Related party notes receivable: Related Party Revenue [Abstract] Related party transactions: The US-GAAP taxonomy only contains a single date for related party transactions. RelatedPartyTransaction Date. We disclose our earliest and latest maturities on the various outstanding notes only by the year. Related Party Transaction Date, Earliest Maturity Earliest maturity year Rental Trucks and Rental Trailers and Other Rental Equipment are defined to be under the same US-GAAP concept, "Property subject to or available for operating lease, gross." The equipment is maintained so that our customers can complete a rental contract for a do-it-yourself move. Rental Trailers and Other Rental Equipment [Member] Rental trailers and other rental equipment Rental Trucks and Rental Trailers and Other Rental Equipment are defined to be under the same US-GAAP concept, "Property subject to or available for operating lease, gross." This equipment is maintained so that our customers can complete a rental contract for a do-it-yourself move. Rental Trucks [Member] Rental trucks Repwest provides property and casualty insurance to AMERCO and insures U-Haul customers, dealers and independent third parties. The majority of U-Haul customers purchase Repwest products. In addition, Repwest's business activities include direct and assumed reinsurance underwriting. Repwest [Member] Repwest Arrangement in which the loan proceeds can continuously be obtained following repayments, but the total amount borrowed cannot exceed a specified maximum amount. Revolving Fleet Loan One [Member] Revolving fleet loan one [Member] Debt arrangement having an initial term longer than one year or beyond the normal operating cycle with a provision to extend the life of the loan passed it's original maturity date. Revolving Fleet Loan Three [Member] Revolving fleet loan three [Member] Arrangement that allows loan proceeds to continuously be obtained following repayments, but the total amount borrowed cannot exceed a specified maximum amount. Revolving Fleet Loan Two [Member] Revolving fleet loan two [Member] Amerco has agreements and notes with these entities. Sac Holdings, Four Sac, Five Sac, Galaxy, and Private Mini [Member] SAC Holdings, Four SAC, Five SAC, Galaxy, and Private Mini Substantially all of the equity interest in SAC Holdings is controlled by Blackwater investments, Inc. ("Blackwater"). Sac Holdings [Member] SAC Holdings Amerco manages the self-storage properties of these entities. Sac Holdings, Mercury, Four Sac, Five Sac, Galaxy and Private Mini [Member] SAC Holdings, Mercury, Four SAC, Five SAC, Galaxy and Private Mini This company-specific concept is a combination of two separate concepts in the US-GAAP taxonomy. (1) Other Real Estate Revenue: "Other real estate revenue not otherwise specified in the taxonomy." (2) Contracts Revenue: "Revenue earned during the period arising from products sold or services provided under the terms of a contract, not elsewhere specified in the taxonomy. May include government contracts, construction contracts, and any other contract related to a particular project or product. Self Storage Revenues Self-storage revenues Create a common stock member to incorporate the value shown in the heading of this section. Series Common Stock With or Without Par Value [Member] Series common stock, with or without par value, 150,000,000 shares authorized: This member further defines the concepts that follow. In this way, share concepts can be repeated and are unique to the taxonomy. Series Preferred Stock With or Without Par Value [Member] Series preferred stock, with or without par value, 50,000,000 shares authorized: AMERCO has been leasing equipment for several decades with no material losses relating to these types of residual value guarantees. This provides the original date when the Company started leasing. Started Leasing Equipment Date Lease equipment start date The amount of corporate (parent company) debt held by our insurance subsidiaries. Subsidiaries Share of Debt Purchased from Parent Subsidiary holdings of parent company debt On our HTML document, we leave this field name blank. It is considered the sum of all assets prior to our listing all Property, Plant and Equipment items. Subtotal Assets Subtotal assets Summary of Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Abstract] This is the tenth of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Eleven [Member] Swap Agreement Eleven This is the fourteen of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Fifteen [Member] Swap Agreement Fifteen This is the thirteen of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Fourteen [Member] Swap Agreement Fourteen This is the sixteen of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Seventeen [Member] Swap Agreement Seventeen This is the fifteen of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Sixteen [Member] Swap Agreement Sixteen This is the twelve of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Thirteen [Member] Swap Agreement Thirteen This is the second of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Three [Member] Swap Agreement Three This is the eleven of sixteen active swap agreements. The Company manages exposure to changes in market interest rates. The Company's use of derivative instruments is limited to highly effective interest rate swaps to hedge the risk of changes in cash flows (future interest payments) attributable to changes in LIBOR swap rates, the designated benchmark interest rate being hedged on certain of our LIBOR indexed variables rate debt. The interest rate swaps effectively fix the Company's interest payments on certain LIBOR index variable rate debt. The Company monitors its positions and the credit ratings of its counterparties and does not currently anticipate non-performance by the counterparties. Interest rate swap agreements are not entered into for trading purposes. Swap Agreement Twelve [Member] Swap Agreement Twelve Timing difference for interecompany balances with insurance subsidiaries. The balance includes the redemption of our Preferred stock. Timing Difference Insurance Subsidiaries Other Subsidiaries who are borrowers under amortizing term loans Uhaul Intl and Subsidiaries [Member] U-Haul Int'l and Subsidiaries U-Haul International, North America's largest "do-it-yourself" moving and storage operator. Uhaul [Member] U-Haul Borrowers of the U-Haul S Fleet ("2007 Box Truck Note") asset-backed note. Uhaul S Fleet Two Thousand and Seven Box Truck Note [Member] U-Haul S Fleet, 2007 Box Truck Note Borrowers of the U-Haul S Fleet ("2010 Box Truck Note") asset-backed note. Uhaul S Fleet Two Thousand Ten Box Truck Note [Member] U-Haul S Fleet, 2010 Box Truck Note The adjusted cost and estimated market value of available-for-sale investments by contractual maturity schedule requires a subtotal for the Due after... information (group 102010). In order to accomplish this, added this hierarchy to this group. Us Treasury, Government, and Corporate Securities [Member] U.S. treasury, government, and corporate securities Combination of subsidiary companies holds various junior unsecured notes due from SAC Holdings, a related party. Various Subsidiaries of Amerco [Member] Various Subsidiaries of Amerco Affiliates of Amerco with outstanding senior mortgage notes Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] Various Subsidiaries of Amerco Real Estate and U-Haul Int'l Accounting Policies [Abstract] Accounts Payable and Accrued Liabilities Accounts payable and accrued expenses Accumulated Defined Benefit Plans Adjustment [Member] Postretirement Benefit Obligation Gain [Member] Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: Accumulated depreciation Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] Fair Market Value of Cash Flow Hedges [Member] Accumulated Net Unrealized Investment Gain (Loss) [Member] Unrealized Net Gain on Investments [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Balance as of September 30, 2016 Balance as of March 31, 2016 Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss) [Table]