Schedule I - Condensed Financial Information of AMERCO (Statements of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Cash flow from operating activities:
Net earnings	$ 442,048	$ 370,857	$ 790,583
Earnings from consolidated subsidiaries	0	0	0
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	664,120	581,025	555,069
Net loss on sales of investments	(13,596)	(2,663)	(6,269)
Deferred income taxes	317,893	106,811	(193,434)
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	38,129	(31,365)	(15,329)
Prepaid expenses	(391,120)	(8,620)	(40,765)
Other assets	(1,295)	157,152	(165,968)
Related party assets	(5,645)	4,194	53,408
Accounts payable and accrued expenses	(4,530)	10,263	(36,980)
Net cash provided by operating activities	1,075,513	975,583	937,684
Cash flow from investing activities:
Purchases of property, plant and equipment	(2,309,406)	(1,869,968)	(1,363,745)
Proceeds of equity securities	185	8,608	0
Net cash used by investing activities	(1,766,649)	(1,571,136)	(898,304)
Cash flow from financing activities:
Common stock dividends paid	(29,404)	(39,179)	(29,380)
Net contribution from (to) related party	0
Net Cash Provided by (Used in) Financing Activities	512,320	514,582	16,604
Effects of exchange rate on cash	(533)	(4,716)	5,598
Increase (decrease) in cash and cash equivalents	(179,349)	(85,687)	61,582
Cash and cash equivalents at the beginning of period	673,701	759,388	697,806
Cash and cash equivalents at the end of the period	494,352	673,701	759,388
Amerco [Member]
Cash flow from operating activities:
Net earnings	442,048	370,857	790,583
Earnings from consolidated subsidiaries	(205,940)	(279,589)	(681,786)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	1	1	3
Net loss on sales of investments	0	0	0
Deferred income taxes	323,980	112,434	(182,358)
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	0	0	0
Prepaid expenses	(381,190)	(6,289)	(36,516)
Other assets	22	(40)	65
Related party assets	0	0	0
Accounts payable and accrued expenses	1,935	2,260	278
Net cash provided by operating activities	180,856	199,634	(109,731)
Cash flow from investing activities:
Purchases of property, plant and equipment	0	(1)	(1)
Proceeds of equity securities	0	0	0
Net cash used by investing activities	0	(1)	(1)
Cash flow from financing activities:
Proceeds from (repayments) of intercompany loans	(311,534)	(196,382)	250,214
Common stock dividends paid	(29,404)	(39,179)	(29,380)
Net contribution from (to) related party	21,600	0	0
Net Cash Provided by (Used in) Financing Activities	(319,338)	(235,561)	220,834
Effects of exchange rate on cash	4,060	(4,331)	(3,124)
Increase (decrease) in cash and cash equivalents	(134,422)	(40,259)	107,978
Cash and cash equivalents at the beginning of period	428,950	469,209	361,231
Cash and cash equivalents at the end of the period	$ 294,528	$ 428,950	$ 469,209