Schedule I - Condensed Financial Information of AMERCO (Statements of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Cash flow from operating activities:
Net earnings	$ 1,123,286	$ 610,856	$ 442,048
Earnings from consolidated subsidiaries	0	0	0
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	696,955	664,001	664,120
Net loss on sales of investments	(11,872)	(10,058)	(13,596)
Deferred income taxes	101,091	68,411	317,893
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	(9,187)	(39,516)	38,129
Prepaid expenses	232,342	94,359	(391,120)
Other assets	(2,706)	29,865	(1,295)
Related party assets	(10,357)	(487)	(5,645)
Accounts payable and accrued expenses	28,752	92,925	(4,530)
Net cash provided by operating activities	1,946,235	1,535,395	1,075,513
Cash flow from investing activities:
Purchases of property, plant and equipment	(2,136,537)	(1,441,475)	(2,309,406)
Proceeds of equity securities	2,046	207	185
Net cash used by investing activities	(1,867,176)	(1,129,529)	(1,766,649)
Cash flow from financing activities:
Borrowings from credit facilities	1,969,474	922,008	1,121,412
Principal repayments on credit facilities	(437,506)	(662,588)	(349,986)
Debt issuance costs	(13,156)	(5,793)	(5,332)
Common stock dividends paid	(29,412)	(49,019)	(29,404)
Net contribution from (to) related party		0	0
Net Cash Provided by (Used in) Financing Activities	1,433,155	287,353	512,320
Effects of exchange rate on cash	(2,089)	6,441	(533)
Increase (decrease) cash and cash equivalents	1,510,125	699,660	(179,349)
Cash and cash equivalents at the beginning of period	1,194,012	494,352	673,701
Cash and cash equivalents at the end of the period	2,704,137	1,194,012	494,352
Amerco [Member]
Cash flow from operating activities:
Net earnings	1,123,286	610,856	442,048
Earnings from consolidated subsidiaries	(1,011,841)	(508,632)	(205,940)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	1	1	1
Net loss on sales of investments	292	924	0
Deferred income taxes	106,869	72,407	323,980
Net change in other operating assets and liabilities:
Prepaid expenses	234,490	88,898	(381,190)
Other assets	(4)	0	22
Related party assets	(240)	(12,000)	0
Accounts payable and accrued expenses	5,461	(4,019)	1,935
Net cash provided by operating activities	458,314	248,435	180,856
Cash flow from investing activities:
Purchases of property, plant and equipment	(11)	(3)	0
Proceeds of equity securities	0	0	0
Net cash used by investing activities	(11)	(3)	0
Cash flow from financing activities:
Borrowings from credit facilities	1,200,000	200,000	0
Principal repayments on credit facilities	0	(200,000)	0
Debt issuance costs	(8,468)	(924)	0
Proceeds from (repayments) of intercompany loans	(284,438)	211,064	(311,534)
Common stock dividends paid	(29,412)	(49,019)	(29,404)
Net contribution from (to) related party	0	41,199	21,600
Net Cash Provided by (Used in) Financing Activities	877,682	202,320	(319,338)
Effects of exchange rate on cash	(1,591)	5,773	4,060
Increase (decrease) cash and cash equivalents	1,334,394	456,525	(134,422)
Cash and cash equivalents at the beginning of period	751,053	294,528	428,950
Cash and cash equivalents at the end of the period	$ 2,085,447	$ 751,053	$ 294,528