Consolidating Financial Information By Industry Segment (Table Text Block)	3 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Table Text Block Supplement [Abstract]
Consolidated Balance Sheet by Industry Segment	Consolidating balance sheets by industry segment as of June 30, 2022 are as follows:       Moving & Storage Consolidated   Property & Casualty Insurance (a)   Life Insurance (a)   Eliminations     AMERCO Consolidated     (Unaudited)     (In thousands) Assets:   Cash and cash equivalents $ 2,982,541 $ 9,065 $ 106,665 $ –   $ 3,098,271 Reinsurance recoverables and trade receivables, net   130,412   52,491   36,671   –     219,574 Inventories and parts, net   164,579   –   –   –     164,579 Prepaid expenses   231,714   –   –   –     231,714 Investments, fixed maturities and marketable equities   –   282,715   2,387,271   –     2,669,986 Investments, other   20,653   116,696   419,775   –     557,124 Deferred policy acquisition costs, net   –   –   129,568   –     129,568 Other assets   50,043   480   2,954   –     53,477 Right of use assets - financing, net   568,223   –   –   –     568,223 Right of use assets - operating, net   71,357   1,101   80   –     72,538 Related party assets   63,718   6,964   15,364   (40,856) (c)   45,190     4,283,240   469,512   3,098,348   (40,856)     7,810,244                         Investment in subsidiaries   606,813   –   –   (606,813) (b)   –                         Property, plant and equipment, at cost:                       Land   1,354,587   –   –   –     1,354,587 Buildings and improvements   6,154,373   –   –   –     6,154,373 Furniture and equipment   858,094   –   –   –     858,094 Rental trailers and other rental equipment   671,880   –   –   –     671,880 Rental trucks   4,873,554   –   –   –     4,873,554     13,912,488   –   –   –     13,912,488 Less:   Accumulated depreciation   (3,891,128)   –   –   –     (3,891,128) Total property, plant and equipment, net   10,021,360   –   –   –     10,021,360 Total assets $ 14,911,413 $ 469,512 $ 3,098,348 $ (647,669)   $ 17,831,604                         (a) Balances as of March 31, 2022                       (b) Eliminate investment in subsidiaries                       (c) Eliminate intercompany receivables and payables                       Consolidating balance sheets by industry segment as of June 30, 2022, continued       Moving & Storage   Property & Casualty Insurance (a)   Life   Eliminations     AMERCO     (Unaudited)     (In thousands) Liabilities:                       Accounts payable and accrued expenses $ 712,167 $ 3,299 $ 7,151 $ –   $ 722,617 Notes, loans and finance leases payable, net   6,232,564   –   –   –     6,232,564 Operating lease liabilities   71,083   1,108   86   –     72,277 Policy benefits and losses, claims and loss expenses payable   427,155   159,142   401,733   –     988,030 Liabilities from investment contracts   –   –   2,374,250   –     2,374,250 Other policyholders' funds and liabilities   –   3,362   8,637   –     11,999 Deferred income   63,647   –   –   –     63,647 Deferred income taxes, net   1,306,768   9,412   (23,811)   –     1,292,369 Related party liabilities   26,918   3,701   12,977   (43,596) (c)   – Total liabilities   8,840,302   180,024   2,781,023   (43,596)     11,757,753                         Stockholders' equity:                       Series preferred stock:                       Series A preferred stock   –   –   –   –     – Series B preferred stock   –   –   –   –     – Series A common stock   –   –   –   –     – Common stock   10,497   3,301   2,500   (5,801) (b)   10,497 Additional paid-in capital   454,029   91,120   26,271   (117,601) (b)   453,819 Accumulated other comprehensive income (loss)   (91,986)   3,394   (37,490)   36,836 (b)   (89,246) Retained earnings   6,376,221   191,673   326,044   (517,507) (b)   6,376,431 Cost of common stock in treasury, net   (525,653)   –   –   –     (525,653) Cost of preferred stock in treasury, net   (151,997)   –   –   –     (151,997) Total stockholders' equity   6,071,111   289,488   317,325   (604,073)     6,073,851 Total liabilities and stockholders' equity $ 14,911,413 $ 469,512 $ 3,098,348 $ (647,669)   $ 17,831,604                         (a) Balances as of March 31, 2022                       (b) Eliminate investment in subsidiaries                       (c) Eliminate intercompany receivables and payables	Consolidating balance sheets by industry segment as of March 31, 2022 are as follows:       Moving & Storage Consolidated   Property & Casualty Insurance (a)   Life Insurance (a)   Eliminations     AMERCO Consolidated       Assets:   (In thousands) Cash and cash equivalents $   2,643,213 $   10,800 $   50,124 $   –   $   2,704,137 Reinsurance recoverables and trade receivables, net   142,895   50,235   36,213   –     229,343 Inventories and parts, net   158,888   –   –   –     158,888 Prepaid expenses   236,915   –   –   –     236,915 Investments, fixed maturities and marketable equities   –   297,488   2,595,911   –     2,893,399 Investments, other   20,653   114,269   408,833   –     543,755 Deferred policy acquisition costs, net   –   –   103,828   –     103,828 Other assets   57,305   371   2,733   –     60,409 Right of use assets - financing, net   620,824   –   –   –     620,824 Right of use assets - operating, net   74,190   93   99   –     74,382 Related party assets   64,611   6,713   16,911   (40,384) (c)   47,851     4,019,494   479,969   3,214,652   (40,384)     7,673,731                         Investment in subsidiaries   737,073   –   –   (737,073) (b)   –                         Property, plant and equipment, at cost:                       Land   1,283,142   –   –   –     1,283,142 Buildings and improvements   5,974,639   –   –   –     5,974,639 Furniture and equipment   846,132   –   –   –     846,132 Rental trailers and other rental equipment   615,679   –   –   –     615,679 Rental trucks   4,638,814   –   –   –     4,638,814     13,358,406   –   –   –     13,358,406 Less:   Accumulated depreciation   (3,732,556)   –   –   –     (3,732,556) Total property, plant and equipment, net   9,625,850   –   –   –     9,625,850 Total assets $   14,382,417 $   479,969 $   3,214,652 $   (777,457)   $   17,299,581                         (a) Balances as of December 31, 2021                       (b) Eliminate investment in subsidiaries                       (c) Eliminate intercompany receivables and payables                       Consolidating balance sheets by industry segment as of March 31, 2022, continued       Moving & Storage   Property & Casualty Insurance (a)   Life   Eliminations     AMERCO                             (In thousands) Liabilities:                       Accounts payable and accrued expenses $ 663,482 $ 3,849 $ 10,454 $ –   $ 677,785 Notes, loans and finance leases payable, net   6,022,497   –   –   –     6,022,497 Operating lease liabilities   73,998   93   106   –     74,197 Policy benefits and losses, claims and loss expenses payable   418,890   160,379   398,985   –     978,254 Liabilities from investment contracts   –   –   2,336,238   –     2,336,238 Other policyholders' funds and liabilities   –   3,521   7,291   –     10,812 Deferred income   49,157   –   –   –     49,157 Deferred income taxes, net   1,244,639   12,803   7,916   –     1,265,358 Related party liabilities   25,668   3,196   12,717   (41,581) (c)   – Total liabilities   8,498,331   183,841   2,773,707   (41,581)     11,414,298                         Stockholders' equity:                       Series preferred stock:                       Series A preferred stock   –   –   –   –     – Series B preferred stock   –   –   –   –     – Series A common stock   –   –   –   –     – Common stock   10,497   3,301   2,500   (5,801) (b)   10,497 Additional paid-in capital   454,029   91,120   26,271   (117,601) (b)   453,819 Accumulated other comprehensive income (loss)   45,187   16,630   87,200   (102,633) (b)   46,384 Retained earnings   6,052,023   185,077   324,974   (509,841) (b)   6,052,233 Cost of common shares in treasury, net   (525,653)   –   –   –     (525,653) Cost of preferred shares in treasury, net   (151,997)   –   –   –     (151,997) Total stockholders' equity   5,884,086   296,128   440,945   (735,876)     5,885,283 Total liabilities and stockholders' equity $ 14,382,417 $ 479,969 $ 3,214,652 $ (777,457)   $ 17,299,581                         (a) Balances as of December 31, 2021                       (b) Eliminate investment in subsidiaries                       (c) Eliminate intercompany receivables and payables
Consolidated Statement of Operations by Industry Segment	Consolidating statement of operations by industry segment for the quarter ended June 30, 2022 are as follows:       Moving & Storage   Property & Casualty Insurance (a)   Life   Eliminations     AMERCO     (Unaudited)     (In thousands) Revenues:                       Self-moving equipment rentals $ 1,091,710 $ – $ – $ (935) (c) $ 1,090,775 Self-storage revenues   173,177   –   –   –     173,177 Self-moving and self-storage products and service sales   109,351   –   –   –     109,351 Property management fees   9,139   –   –   –     9,139 Life insurance premiums   –   –   25,781   –     25,781 Property and casualty insurance premiums   –   20,830   –   (858) (c)   19,972 Net investment and interest income   4,940   2,252   27,388   (1,007) (b)   33,573 Other revenue   135,281   –   934   (143) (b)   136,072 Total revenues   1,523,598   23,082   54,103   (2,943)     1,597,840                         Costs and expenses:                       Operating expenses   719,794   10,194   5,109   (1,930) (b,c)   733,167 Commission expenses   118,493   –   –   –     118,493 Cost of sales   79,671   –   –   –     79,671 Benefits and losses   –   4,379   39,721   –     44,100 Amortization of deferred policy acquisition costs   –   –   7,672   –     7,672 Lease expense   7,920   158   28   (631) (b)   7,475 Depreciation, net of gains on disposals   113,796   –   –   –     113,796 Net losses on disposal of real estate   2,307   –   –   –     2,307 Total costs and expenses   1,041,981   14,731   52,530   (2,561)     1,106,681                         Earnings from operations before equity in earnings of subsidiaries   481,617   8,351   1,573   (382)     491,159                         Equity in earnings of subsidiaries   7,666   –   –   (7,666) (d)   –                         Earnings from operations   489,283   8,351   1,573   (8,048)     491,159 Other components of net periodic benefit costs   (304)   –   –   –     (304) Interest expense   (50,061)   –   (120)   382 (b)   (49,799) Pretax earnings   438,918   8,351   1,453   (7,666)     441,056 Income tax expense   (104,916)   (1,755)   (383)   –     (107,054) Earnings available to common stockholders $ 334,002 $ 6,596 $ 1,070 $ (7,666)   $ 334,002                         (a) Balances for the quarter ended March 31, 2022                       (b) Eliminate intercompany lease / interest income                       (c) Eliminate intercompany premiums                       (d) Eliminate equity in earnings of subsidiaries	Consolidating statements of operations by industry for the quarter ended June 30, 2021 are as follows:       Moving & Storage   Property & Casualty Insurance (a)   Life   Eliminations     AMERCO     (Unaudited)     (In thousands) Revenues:                       Self-moving equipment rentals $ 1,036,213 $ – $ – $ (836) (c) $ 1,035,377 Self-storage revenues   137,393   –   –   –     137,393 Self-moving and self-storage products and service sales   104,885   –   –   –     104,885 Property management fees   8,449   –   –   –     8,449 Life insurance premiums   –   –   28,705   –     28,705 Property and casualty insurance premiums   –   17,443   –   (574) (c)   16,869 Net investment and interest income   680   6,013   29,324   (1,018) (b)   34,999 Other revenue   105,634   –   630   (85) (b)   106,179 Total revenues   1,393,254   23,456   58,659   (2,513)     1,472,856                         Costs and expenses:                       Operating expenses   601,831   8,813   5,375   (1,490) (b,c)   614,529 Commission expenses   113,149   –   –   –     113,149 Cost of sales   69,915   –   –   –     69,915 Benefits and losses   –   5,227   42,071   –     47,298 Amortization of deferred policy acquisition costs   –   –   8,823   –     8,823 Lease expense   8,077   184   24   (638) (b)   7,647 Depreciation, net of gains on disposals   121,717   –   –   –     121,717 Net gains on disposal of real estate   (4,430)   –   –   –     (4,430) Total costs and expenses   910,259   14,224   56,293   (2,128)     978,648                         Earnings from operations before equity in earnings of subsidiaries   482,995   9,232   2,366   (385)     494,208                         Equity in earnings of subsidiaries   9,119   –   –   (9,119) (d)   –                         Earnings from operations   492,114   9,232   2,366   (9,504)     494,208 Other components of net periodic benefit costs   (280)   –   –   –     (280) Interest expense   (39,443)   –   (120)   385 (b)   (39,178) Pretax earnings   452,391   9,232   2,246   (9,119)     454,750 Income tax expense   (107,216)   (1,930)   (429)   –     (109,575) Earnings available to common stockholders $ 345,175 $ 7,302 $ 1,817 $ (9,119)   $ 345,175                         (a) Balances for the quarter ended March 31, 2021                       (b) Eliminate intercompany lease / interest income                       (c) Eliminate intercompany premiums                       (d) Eliminate equity in earnings of subsidiaries
Consolidated Cash Flow Statement by Industry Segment	Consolidating cash flow statements by industry segment for the quarter ended June 30, 2022 are as follows:     Moving & Storage Consolidated   Property & Casualty Insurance (a)   Life Insurance (a)   Elimination     AMERCO Consolidated     (Unaudited) Cash flows from operating activities:   (In thousands) Net earnings $   334,002 $   6,596 $   1,070 $   (7,666)   $   334,002 Earnings from consolidated entities   (7,666)   –   –   7,666     – Adjustments to reconcile net earnings to the cash provided by operations:                       Depreciation   178,144   –   –   –     178,144 Amortization of deferred policy acquisition costs   –   –   7,672   –     7,672 Amortization of premiums and accretion of discounts related to investments, net   –   421   4,508   –     4,929 Amortization of debt issuance costs   1,473   –   –   –     1,473 Interest credited to policyholders   –   –   15,157   –     15,157 Provision for allowance for losses on trade receivables   (6,075)   (76)   –   –     (6,151) Provision for allowance for inventories and parts reserve   4,646   –   –   –     4,646 Net gains on disposal of personal property   (64,348)   –   –   –     (64,348) Net losses on disposal of real estate   2,307   –   –   –     2,307 Net (gains) losses on sales of investments   –   (31)   299   –     268 Net losses on equity investments   –   1,551   –   –     1,551 Deferred income taxes   61,948   127   1,418   –     63,493 Net change in other operating assets and liabilities:                       Reinsurance recoverables and trade receivables   18,458   (2,107)   (457)   –     15,894 Inventories and parts   (10,347)   –   –   –     (10,347) Prepaid expenses   4,935   –   –   –     4,935 Capitalization of deferred policy acquisition costs   –   –   (7,398)   –     (7,398) Other assets   2,177   (40)   (202)   –     1,935 Related party assets   747   (263)   –   –     484 Accounts payable and accrued expenses   78,549   (549)   (3,324)   –     74,676 Policy benefits and losses, claims and loss expenses payable   8,875   (1,237)   2,748   –     10,386 Other policyholders' funds and liabilities   –   (159)   1,346   –     1,187 Deferred income   14,501   –   (53)   –     14,448 Related party liabilities   1,251   517   260   –     2,028 Net cash provided by operating activities   623,577   4,750   23,044   –     651,371                         Cash flows from investing activities:                       Escrow deposits   4,789   –   –   –     4,789 Purchases of:                       Property, plant and equipment   (646,137)   –   –   –     (646,137) Short term investments   –   (21,966)   (51)   –     (22,017) Fixed maturities investments   –   (9,839)   (26,649)   –     (36,488) Equity securities   –   (1,366)   –   –     (1,366) Preferred stock   –   –   –   –     – Real estate   –   –   –   –     – Mortgage loans   –   (6,975)   (35,586)   –     (42,561) Proceeds from sales and paydowns of:                       Property, plant and equipment   159,180   –   –   –     159,180 Short term investments   –   18,073   –   –     18,073 Fixed maturities investments   –   6,852   48,956   –     55,808 Equity securities   –   362   –   –     362 Mortgage loans   –   8,374   23,971   –     32,345 Net cash (used) provided by investing activities   (482,168)   (6,485)   10,641   –     (478,012)     (page 1 of 2) (a) Balance for the period ended March 31, 2022                       Consolidating cash flow statements by industry segment for the quarter ended June 30, 2022, continued       Moving & Storage   Property &   Life   Elimination     AMERCO     (Unaudited) Cash flows from financing activities:   (In thousands) Borrowings from credit facilities   393,264   –   –   –     393,264 Principal repayments on credit facilities   (145,369)   –   –   –     (145,369) Payments of debt issuance costs   (1,069)   –   –   –     (1,069) Finance lease payments   (34,982)   –   –   –     (34,982) Common stock dividends paid   (9,804)   –   –   –     (9,804) Investment contract deposits   –   –   85,767   –     85,767 Investment contract withdrawals   –   –   (62,911)   –     (62,911) Net cash provided by financing activities   202,040   –   22,856   –     224,896                         Effects of exchange rate on cash   (4,121)   –   –   –     (4,121)                         Increase (decrease) in cash and cash equivalents   339,328   (1,735)   56,541   –     394,134 Cash and cash equivalents at beginning of period   2,643,213   10,800   50,124   –     2,704,137 Cash and cash equivalents at end of period $   2,982,541 $   9,065 $   106,665 $   –   $   3,098,271     (page 2 of 2) (a) Balance for the period ended March 31, 2022	Consolidating cash flow statements by industry segment for the quarter ended June 30, 2021 are as follows:       Moving & Storage Consolidated   Property & Casualty Insurance (a)   Life Insurance (a)   Elimination     AMERCO Consolidated     (Unaudited) Cash flows from operating activities:   (In thousands) Net earnings $   345,175 $   7,302 $   1,817 $   (9,119)   $   345,175 Earnings from consolidated entities   (9,119)   –   –   9,119     – Adjustments to reconcile net earnings to cash provided by operations:                       Depreciation   172,040   –   –   –     172,040 Amortization of deferred policy acquisition costs   –   –   8,823   –     8,823 Amortization of premiums and accretion of discounts related to investments, net   –   413   3,948   –     4,361 Amortization of debt issuance costs   1,332   –   –   –     1,332 Interest credited to policyholders   –   –   15,583   –     15,583 Provision for allowance for losses on trade receivables   (478)   (5)   (1)   –     (484) Provision for allowance for inventories and parts reserve   3,403   –   –   –     3,403 Net gains on disposal of personal property   (50,323)   –   –   –     (50,323) Net gains on disposal of real estate   (4,430)   –   –   –     (4,430) Net gains on sales of investments   –   (37)   (2,432)   –     (2,469) Net gains on equity investments   –   (2,231)   –   –     (2,231) Deferred income taxes   81,341   604   429   –     82,374 Net change in other operating assets and liabilities:                       Reinsurance recoverables and trade receivables   (1,658)   (520)   (5,904)   –     (8,082) Inventories and parts   (15,765)   –   –   –     (15,765) Prepaid expenses   162,706   –   –   –     162,706 Capitalization of deferred policy acquisition costs   –   –   (8,990)   –     (8,990) Other assets   (436)   (323)   (94)   –     (853) Related party assets   302   260   –   –     562 Accounts payable and accrued expenses   60,902   225   10,472   –     71,599 Policy benefits and losses, claims and loss expenses payable   5,942   352   2,770   –     9,064 Other policyholders' funds and liabilities   –   (461)   (969)   –     (1,430) Deferred income   12,125   –   (262)   –     11,863 Related party liabilities   1,422   (1,972)   935   –     385 Net cash provided by operating activities   764,481   3,607   26,125   –     794,213                         Cash flows from investing activities:                       Escrow deposits   1,887   –   –   –     1,887 Purchases of:                       Property, plant and equipment   (508,411)   –   –   –     (508,411) Short term investments   –   (11,680)   (130)   –     (11,810) Fixed maturities investments   –   (7,466)   (274,041)   –     (281,507) Preferred stock   –   –   (8,000)   –     (8,000) Real estate   –   –   (67)   –     (67) Mortgage loans   –   (4,850)   (37,688)   –     (42,538) Proceeds from sales and paydowns of:                       Property, plant and equipment   182,146   –   –   –     182,146 Short term investments   –   12,558   –   –     12,558 Fixed maturities investments   –   5,136   121,820   –     126,956 Mortgage loans   –   283   5,345   –     5,628 Net cash used by investing activities   (324,378)   (6,019)   (192,761)   –     (523,158)     (page 1 of 2) (a) Balance for the period ended March 31, 2021                       Consolidating cash flow statements by industry segment for the quarter ended June 30, 2021, continued       Moving & Storage   Property &   Life   Elimination     AMERCO     (Unaudited) Cash flows from financing activities:   (In thousands) Borrowings from credit facilities   161,854   –   –   –     161,854 Principal repayments on credit facilities   (109,206)   –   (128)   –     (109,334) Payment of debt issuance costs   (352)   –   –   –     (352) Finance lease payments   (45,170)   –   –   –     (45,170) Investment contract deposits   –   –   113,779   –     113,779 Investment contract withdrawals   –   –   (64,332)   –     (64,332) Net cash provided by financing activities   7,126   –   49,319   –     56,445                         Effects of exchange rate on cash   (1,531)   –   –   –     (1,531)                         Increase (decrease) in cash and cash equivalents   445,698   (2,412)   (117,317)   –     325,969 Cash and cash equivalents at beginning of period   1,010,275   5,658   178,079   –     1,194,012 Cash and cash equivalents at end of period $   1,455,973 $   3,246 $   60,762 $   –   $   1,519,981     (page 2 of 2) (a) Balance for the period ended March 31, 2021