Condensed Financial Information of AMERCO, Statements of Cash Flow (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Cash flow from operating activities:
Net earnings	$ 356,741	$ 342,391	$ 264,708
Earnings from consolidated subsidiaries	0	0	0
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	352,796	293,169	260,492
Net (gain) loss on sale of investments	(3,925)	(6,411)	(8,323)
Deferred income taxes	76,500	46,371	13,518
Net change in other operating assets and liabilities:
Prepaid expenses	65,720	(2,186)	15,587
Other assets	(3,735)	(7,667)	(21,556)
Related party assets	27,706	7,554	133,672
Accounts payable and accrued expenses	166,056	34,731	40,032
Net cash provided by operating activities	808,190	709,504	661,530
Cash flow from investing activities:
Purchases of property, plant and equipment	(1,111,899)	(999,365)	(655,984)
Proceeds of equity securities	3,082	29,139	372
Net cash used by investing activities	(825,229)	(845,753)	(712,213)
Cash flow from financing activities:
Proceeds from (repayment of) intercompany loans	0	0	0
Common stock dividends paid	(19,594)	(19,568)	(97,421)
Contribution to related party			0
Net cash provided by financing activities	(25,461)	167,794	157,783
Increase (decrease) in cash and cash equivalents	(53,262)	31,368	106,564
Cash and cash equivalents at the beginning of period	495,112	463,744	357,180
Cash and cash equivalents at the end of the period	441,850	495,112	463,744
AMERCO [Member]
Cash flow from operating activities:
Net earnings	356,741	342,391	264,708
Earnings from consolidated subsidiaries	(300,566)	(287,803)	(212,164)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	6	5	5
Net (gain) loss on sale of investments	0	(1,325)	(76)
Deferred income taxes	66,628	34,605	9,206
Net change in other operating assets and liabilities:
Prepaid expenses	(66,786)	3,938	(12,979)
Other assets	84	(41)	365
Related party assets	(539)	0	0
Accounts payable and accrued expenses	5,239	6,589	2,659
Net cash provided by operating activities	60,807	98,359	51,724
Cash flow from investing activities:
Purchases of property, plant and equipment	0	(2)	(2)
Proceeds of equity securities	0	26,569	372
Net cash used by investing activities	0	26,567	370
Cash flow from financing activities:
Proceeds from (repayment of) intercompany loans	(71,207)	(110,933)	172,444
Common stock dividends paid	(19,594)	(19,568)	(97,421)
Contribution to related party	0	0	(1,500)
Net cash provided by financing activities	(90,801)	(130,501)	73,523
Increase (decrease) in cash and cash equivalents	(29,994)	(5,575)	125,617
Cash and cash equivalents at the beginning of period	321,544	327,119	201,502
Cash and cash equivalents at the end of the period	$ 291,550	$ 321,544	$ 327,119