Schedule I - Condensed Financial Information of AMERCO (Statements of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flow from operating activities:
Net earnings	$ 398,424	$ 489,001	$ 356,741
Earnings from consolidated subsidiaries
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	481,520	389,393	352,796
Net gain (loss) on sale of investments	(5,284)	(4,491)	(3,925)
Deferred income taxes	173,112	138,075	76,500
Net change in other operating assets and liabilities:
Prepaid expenses	9,386	(10,338)	(65,720)
Other assets	(40,546)	11,903	(51)
Related party assets	343	56,644	27,706
Accounts payable and accrued expenses	(5,056)	37,312	98,877
Net cash provided by operating activities	1,020,061	1,040,988	759,099
Cash flow from investing activities:
Purchases of property, plant and equipment	(1,419,505)	(1,509,154)	(1,041,931)
Proceeds of equity securities		2,044	3,082
Net cash used by investing activities	(1,144,514)	(1,255,324)	(755,261)
Cash flow from financing activities:
Common stock dividends paid	(58,757)	(78,374)	(19,594)
Net Cash Provided by (Used in) Financing Activities	223,753	388,872	(46,338)
Increase (decrease) in cash and cash equivalents	97,160	158,796	(53,262)
Cash and cash equivalents at the beginning of period	600,646	441,850	495,112
Cash and cash equivalents at the end of the period	697,806	600,646	441,850
Amerco [Member]
Cash flow from operating activities:
Net earnings	398,424	489,001	356,741
Earnings from consolidated subsidiaries	(327,773)	(417,087)	(300,566)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	10	6	6
Net gain (loss) on sale of investments	13
Deferred income taxes	173,059	124,838	66,628
Net change in other operating assets and liabilities:
Prepaid expenses	16,021	(8,723)	(66,786)
Other assets	(20)	6	84
Related party assets	1	56,849	(539)
Accounts payable and accrued expenses	(297)	(14)	5,239
Net cash provided by operating activities	259,438	244,876	60,807
Cash flow from investing activities:
Purchases of property, plant and equipment	(55)	(8)
Proceeds of equity securities	39
Net cash used by investing activities	(16)	(8)
Cash flow from financing activities:
Proceeds from (repayments) of intercompany loans	(221,124)	(76,354)	(71,207)
Common stock dividends paid	(58,757)	(78,374)	(19,594)
Net Cash Provided by (Used in) Financing Activities	(279,881)	(154,728)	(90,801)
Increase (decrease) in cash and cash equivalents	(20,459)	90,140	(29,994)
Cash and cash equivalents at the beginning of period	381,690	291,550	321,544
Cash and cash equivalents at the end of the period	$ 361,231	$ 381,690	$ 291,550