Schedule I - Condensed Financial Information of AMERCO (Statements of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Cash flow from operating activities:
Net earnings	$ 370,857	$ 790,583	$ 398,424
Earnings from consolidated subsidiaries
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	581,025	555,069	481,520
Net loss on sales of investments	(2,663)	(6,269)	(5,284)
Deferred income taxes	106,811	(193,434)	173,112
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	(31,365)	(15,329)	(2,890)
Prepaid expenses	(8,620)	(40,765)	9,386
Other assets	157,152	(165,968)	(2,488)
Related party assets	4,194	53,408	343
Accounts payable and accrued expenses	10,263	(36,980)	(15,548)
Net cash provided by operating activities	975,583	937,684	1,059,455
Cash flow from investing activities:
Purchases of property, plant and equipment	(1,869,968)	(1,363,745)	(1,419,505)
Proceeds of equity securities	8,608
Net cash used by investing activities	(1,571,136)	(898,304)	(1,183,908)
Cash flow from financing activities:
Common stock dividends paid	(39,179)	(29,380)	(58,757)
Net Cash Provided by (Used in) Financing Activities	514,582	16,604	223,753
Effects of exchange rate on cash	(4,716)	5,598	(2,140)
Increase (decrease) in cash and cash equivalents	(85,687)	61,582	97,160
Cash and cash equivalents at the beginning of period	759,388	697,806	600,646
Cash and cash equivalents at the end of the period	673,701	759,388	697,806
Amerco [Member]
Cash flow from operating activities:
Net earnings	370,857	790,583	398,424
Earnings from consolidated subsidiaries	(279,589)	(681,786)	(327,773)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	1	3	10
Net loss on sales of investments			13
Deferred income taxes	112,434	(182,358)	173,059
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables
Prepaid expenses	(6,289)	(36,516)	16,021
Other assets	(40)	65	(20)
Related party assets			1
Accounts payable and accrued expenses	2,260	278	(297)
Net cash provided by operating activities	199,634	(109,731)	259,438
Cash flow from investing activities:
Purchases of property, plant and equipment	(1)	(1)	(55)
Proceeds of equity securities			39
Net cash used by investing activities	(1)	(1)	(16)
Cash flow from financing activities:
Proceeds from (repayments) of intercompany loans	(196,382)	250,214	(221,124)
Common stock dividends paid	(39,179)	(29,380)	(58,757)
Net Cash Provided by (Used in) Financing Activities	(235,561)	220,834	(279,881)
Effects of exchange rate on cash	(4,331)	(3,124)
Increase (decrease) in cash and cash equivalents	(40,259)	107,978	(20,459)
Cash and cash equivalents at the beginning of period	469,209	361,231	381,690
Cash and cash equivalents at the end of the period	$ 428,950	$ 469,209	$ 361,231