Condensed Financial Information of AMERCO, Statements of Cash Flow (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Cash flow from operating activities:
Net earnings	$ 342,391	$ 264,708	$ 205,367
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	293,169	260,492	229,789
Net (gain) loss on sale of investments	(6,411)	(8,323)	(5,579)
Deferred income taxes	46,371	13,518	104,360
Net change in other operating assets and liabilities:
Prepaid expenses	(2,186)	15,587	(15,748)
Other assets	(7,667)	(21,556)	(5,992)
Related party assets	(7,554)	(133,672)	14,210
Accounts payable and accrued expenses	34,731	40,032	19,469
Net cash provided by operating activities	709,504	661,530	669,842
Cash flow from investing activities:
Purchases of property, plant and equipment	(999,365)	(655,984)	(589,799)
Purchases of equity securities	(1,562)	(16,289)	(9,048)
Proceeds of equity securities	29,139	372	10,222
Net cash used by investing activities	(845,753)	(712,213)	(582,137)
Cash flow from financing activities:
Preferred stock redemption paid			(144,289)
Preferred stock dividends paid			(2,913)
Common stock dividends paid	(19,568)	(97,421)	(19,484)
Contribution to related party			(518)
Net cash used by financing activities	167,794	157,783	(112,745)
Increase (decrease) in cash and cash equivalents	31,368	106,564	(25,334)
Cash and cash equivalents at the beginning of period	463,744	357,180	382,514
Cash and cash equivalents at the end of the period	495,112	463,744	357,180
AMERCO [Member]
Cash flow from operating activities:
Net earnings	342,391	264,708	205,695
Earnings from consolidated subsidiaries	(287,803)	212,164	149,160
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	5	5	5
Net (gain) loss on sale of investments	(1,325)	76	488
Deferred income taxes	34,605	9,206	109,680
Net change in other operating assets and liabilities:
Prepaid expenses	3,938	(12,979)	6,470
Other assets	(41)	365	2,380
Related party assets
Accounts payable and accrued expenses	6,589	2,659	4,163
Net cash provided by operating activities	98,359	51,724	178,745
Cash flow from investing activities:
Purchases of property, plant and equipment	(2)	(2)	(1)
Purchases of equity securities			(8,855)
Proceeds of equity securities	26,569	372	8,800
Net cash used by investing activities	26,567	370	(56)
Cash flow from financing activities:
Proceeds from (repayment of) intercompany loans	(110,933)	172,444	(52,051)
Preferred stock redemption paid			(151,997)
Preferred stock dividends paid			(3,241)
Common stock dividends paid	(19,568)	(97,421)	(19,484)
Contribution to related party		(1,500)	(518)
Net cash used by financing activities	(130,501)	73,523	(227,291)
Increase (decrease) in cash and cash equivalents	(5,575)	125,617	(48,602)
Cash and cash equivalents at the beginning of period	327,119	201,502	250,104
Cash and cash equivalents at the end of the period	$ 321,544	$ 327,119	$ 201,502