Consolidated Balance Sheet by Industry Segment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Mar. 31, 2012		Jun. 30, 2011		Mar. 31, 2011
ASSETS:
Cash and cash equivalents	$ 566,239		$ 350,100		$ 243,753		$ 375,496
Reinsurance recoverables and trade receivables, net	274,593		297,974
Inventories, net	63,438		58,735
Prepaid expenses	41,586		41,858
Investments, fixed maturities and marketable equities	793,382		766,792
Investments, other	262,456		265,631
Deferred policy acquisition costs, net	64,075		63,914
Other assets	100,910		120,525
Related party assets	169,797		316,157
Subtotal assets	2,336,476		2,281,686
Property, plant and equipment, at cost:
Land	297,527		281,140
Buildings and improvements	1,105,315		1,087,119
Furniture and equipment	306,441		308,120
Property, plant and equipment (gross)	3,951,462		3,787,822
Less: Accumulated depreciation	(1,449,102)		(1,415,457)
Total property, plant and equipment	2,502,360		2,372,365
Total assets	4,838,836		4,654,051		4,174,456
Liabilities:
Accounts payable and accrued expenses	382,012		335,326
Notes, loans and leases payable	1,540,538		1,486,211
Policy benefits and losses, claims and loss expenses payable	1,121,200		1,145,943
Liabilities from investment contracts	261,987		240,961
Other policyholders' funds and liabilities	5,389		7,273
Deferred income	37,960		31,525
Deferred income taxes	375,090		370,992
Total liabilities	3,724,176		3,618,231
Stockholders' equity:
Additional paid-in capital	434,527		433,743
Accumulated other comprehensive loss	(46,391)		(45,436)
Retained earnings	1,395,913		1,317,064
Unearned employee stock ownership plan shares	(2,236)		(2,398)
Total stockholders' equity	1,114,660		1,035,820
Total liabilities and stockholders' equity	4,838,836		4,654,051
Property and Casualty Insurance
ASSETS:
Cash and cash equivalents	13,089	[1]	15,462	[2]	19,504	[3]	14,700	[3]
Reinsurance recoverables and trade receivables, net	193,059	[1]	231,211	[2]
Investments, fixed maturities and marketable equities	130,227	[1]	132,270	[2]
Investments, other	85,800	[1]	81,837	[2]
Other assets	343	[1]	1,507	[2]
Related party assets	7,761	[1]	7,542	[2]
Subtotal assets	430,279	[1]	469,829	[2]
Property, plant and equipment, at cost:
Total assets	430,279	[1]	469,829	[2]
Liabilities:
Policy benefits and losses, claims and loss expenses payable	340,167	[1]	382,939	[2]
Other policyholders' funds and liabilities	2,735	[1]	3,438	[2]
Deferred income taxes	(41,349)	[1]	(41,945)	[2]
Related party liabilities	1,657	[1]	1,555	[2]
Total liabilities	303,210	[1]	345,987	[2]
Stockholders' equity:
Common stock, value, issued	3,301	[1]	3,301	[2]
Additional paid-in capital	89,620	[1]	89,620	[2]
Accumulated other comprehensive loss	3,801	[1]	2,255	[2]
Retained earnings	30,347	[1]	28,666	[2]
Total stockholders' equity	127,069	[1]	123,842	[2]
Total liabilities and stockholders' equity	430,279	[1]	469,829	[2]
Life Insurance
ASSETS:
Cash and cash equivalents	33,458	[1]	25,410	[2]	33,129	[3]	37,301	[3]
Reinsurance recoverables and trade receivables, net	31,913	[1]	29,660	[2]
Investments, fixed maturities and marketable equities	648,644	[1]	617,494	[2]
Investments, other	120,794	[1]	131,461	[2]
Deferred policy acquisition costs, net	64,075	[1]	63,914	[2]
Other assets	242	[1]	203	[2]
Related party assets	514	[1]	482	[2]
Subtotal assets	899,640	[1]	868,624	[2]
Property, plant and equipment, at cost:
Total assets	899,640	[1]	868,624	[2]
Liabilities:
Accounts payable and accrued expenses	8,753	[1]	10,060	[2]
Policy benefits and losses, claims and loss expenses payable	394,618	[1]	382,864	[2]
Liabilities from investment contracts	261,987	[1]	240,961	[2]
Other policyholders' funds and liabilities	2,654	[1]	3,835	[2]
Deferred income taxes	15,201	[1]	14,945	[2]
Related party liabilities	151	[1]	172	[2]
Total liabilities	683,364	[1]	652,837	[2]
Stockholders' equity:
Common stock, value, issued	2,500	[1]	2,500	[2]
Additional paid-in capital	26,271	[1]	26,271	[2]
Accumulated other comprehensive loss	25,196	[1]	23,888	[2]
Retained earnings	162,309	[1]	163,128	[2]
Total stockholders' equity	216,276	[1]	215,787	[2]
Total liabilities and stockholders' equity	899,640	[1]	868,624	[2]
Eliminations
ASSETS:
Related party assets	(10,088)	[4]	(10,057)	[4]
Subtotal assets	(10,088)		(10,057)
Investments in subsidiaries	(344,845)	[5]	(339,629)	[5]
Property, plant and equipment, at cost:
Total assets	(354,933)		(349,686)
Liabilities:
Related party liabilities	(11,588)	[4]	(10,057)	[4]
Total liabilities	(11,588)		(10,057)
Stockholders' equity:
Common stock, value, issued	(5,801)	[5]	(5,801)	[5]
Additional paid-in capital	(116,101)	[5]	(116,101)	[5]
Accumulated other comprehensive loss	(28,997)	[5]	(26,143)	[5]
Retained earnings	(192,446)	[5]	(191,584)	[5]
Total stockholders' equity	(343,345)		(339,629)
Total liabilities and stockholders' equity	(354,933)		(349,686)
Moving and Storage Consolidations
ASSETS:
Cash and cash equivalents	519,692		309,228		191,120		323,495
Reinsurance recoverables and trade receivables, net	49,621		37,103
Inventories, net	63,438		58,735
Prepaid expenses	41,586		41,858
Investments, fixed maturities and marketable equities	14,511		17,028
Investments, other	55,862		52,333
Other assets	100,325		118,815
Related party assets	171,610		318,190
Subtotal assets	1,016,645		953,290
Investments in subsidiaries	344,845		339,629
Property, plant and equipment, at cost:
Land	297,527		281,140
Buildings and improvements	1,105,315		1,087,119
Furniture and equipment	306,441		308,120
Property, plant and equipment (gross)	3,951,462		3,787,822
Less: Accumulated depreciation	(1,449,102)		(1,415,457)
Total property, plant and equipment	2,502,360		2,372,365
Total assets	3,863,850		3,665,284
Liabilities:
Accounts payable and accrued expenses	373,259		325,266
Notes, loans and leases payable	1,540,538		1,486,211
Policy benefits and losses, claims and loss expenses payable	386,415		380,140
Deferred income	37,960		31,525
Deferred income taxes	401,238		397,992
Related party liabilities	9,780		8,330
Total liabilities	2,749,190		2,629,464
Stockholders' equity:
Common stock, value, issued	10,497		10,497
Additional paid-in capital	434,737		433,953
Accumulated other comprehensive loss	(46,391)		(45,436)
Retained earnings	1,395,703		1,316,854
Unearned employee stock ownership plan shares	(2,236)		(2,398)
Total stockholders' equity	1,114,660		1,035,820
Total liabilities and stockholders' equity	3,863,850		3,665,284
AMERCO /NV/
ASSETS:
Cash and cash equivalents	200,250		201,502		69,618		250,104
Prepaid expenses			9,496
Investments, fixed maturities and marketable equities	14,511		17,028
Other assets	480		483
Related party assets	1,256,503		1,201,385
Subtotal assets	1,471,744		1,429,894
Investments in subsidiaries	75,169		8,168
Property, plant and equipment, at cost:
Furniture and equipment	138		138
Property, plant and equipment (gross)	138		138
Less: Accumulated depreciation	(116)		(115)
Total property, plant and equipment	22		23
Total assets	1,546,935		1,438,085
Liabilities:
Accounts payable and accrued expenses	28,801		1,875
Deferred income taxes	401,238		397,992
Total liabilities	430,039		399,867
Stockholders' equity:
Common stock, value, issued	10,497		10,497
Additional paid-in capital	434,737		433,953
Accumulated other comprehensive loss	(46,391)		(45,436)
Retained earnings	1,395,703		1,316,854
Total stockholders' equity	1,116,896		1,038,218
Total liabilities and stockholders' equity	1,546,935		1,438,085
U-Haul
ASSETS:
Cash and cash equivalents	318,687		106,951		120,663		72,634
Reinsurance recoverables and trade receivables, net	49,621		37,103
Inventories, net	63,438		58,735
Prepaid expenses	41,109		32,051
Investments, other	6,899		9,880
Other assets	73,015		91,761
Related party assets	114,775		261,341
Subtotal assets	667,544		597,822
Property, plant and equipment, at cost:
Land	71,266		67,558
Buildings and improvements	167,323		162,351
Furniture and equipment	287,919		289,601
Property, plant and equipment (gross)	2,768,687		2,630,953
Less: Accumulated depreciation	(1,086,698)		(1,056,854)
Total property, plant and equipment	1,681,989		1,574,099
Total assets	2,349,533		2,171,921
Liabilities:
Accounts payable and accrued expenses	340,668		319,780
Notes, loans and leases payable	829,712		769,497
Policy benefits and losses, claims and loss expenses payable	386,415		380,140
Deferred income	37,960		31,525
Related party liabilities	877,570		855,016
Total liabilities	2,472,325		2,355,958
Stockholders' equity:
Common stock, value, issued	540		540
Additional paid-in capital	121,230		121,230
Accumulated other comprehensive loss	(68,550)		(66,302)
Retained earnings	(173,776)		(237,107)
Unearned employee stock ownership plan shares	(2,236)		(2,398)
Total stockholders' equity	(122,792)		(184,037)
Total liabilities and stockholders' equity	2,349,533		2,171,921
Real Estate
ASSETS:
Cash and cash equivalents	755		775		839		757
Prepaid expenses	477		311
Investments, other	48,963		42,453
Other assets	26,830		26,571
Related party assets	7		9
Subtotal assets	77,032		70,119
Property, plant and equipment, at cost:
Land	226,261		213,582
Buildings and improvements	937,992		924,768
Furniture and equipment	18,384		18,381
Property, plant and equipment (gross)	1,182,637		1,156,731
Less: Accumulated depreciation	(362,288)		(358,488)
Total property, plant and equipment	820,349		798,243
Total assets	897,381		868,362
Liabilities:
Accounts payable and accrued expenses	3,790		3,611
Notes, loans and leases payable	710,826		716,714
Related party liabilities	331,885		297,859
Total liabilities	1,046,501		1,018,184
Stockholders' equity:
Common stock, value, issued	1		1
Additional paid-in capital	147,941		147,941
Retained earnings	(297,062)		(297,764)
Total stockholders' equity	(149,120)		(149,822)
Total liabilities and stockholders' equity	897,381		868,362
Eliminations
ASSETS:
Related party assets	(1,199,675)	[4]	(1,144,545)	[4]
Subtotal assets	(1,199,675)		(1,144,545)
Investments in subsidiaries	269,676	[5]	331,461	[5]
Property, plant and equipment, at cost:
Total assets	(929,999)		(813,084)
Liabilities:
Related party liabilities	(1,199,675)	[4]	(1,144,545)	[4]
Total liabilities	(1,199,675)		(1,144,545)
Stockholders' equity:
Common stock, value, issued	(541)	[5]	(541)	[5]
Additional paid-in capital	(269,171)	[5]	(269,171)	[5]
Accumulated other comprehensive loss	68,550	[5]	66,302	[5]
Retained earnings	470,838	[5]	534,871	[5]
Total stockholders' equity	269,676		331,461
Total liabilities and stockholders' equity	(929,999)		(813,084)
Rental trailers and other rental equipment
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	270,621		255,010
Rental trailers and other rental equipment | Moving and Storage Consolidations
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	270,621		255,010
Rental trailers and other rental equipment | U-Haul
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	270,621		255,010
Rental trucks
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	1,971,558		1,856,433
Rental trucks | Moving and Storage Consolidations
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	1,971,558		1,856,433
Rental trucks | U-Haul
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	1,971,558		1,856,433
Series A preferred stock
Stockholders' equity:
Preferred stock, value, issued
Series B preferred stock
Stockholders' equity:
Preferred stock, value, issued
Series A common stock
Stockholders' equity:
Common stock, value, issued
Common stock
Stockholders' equity:
Common stock, value, issued	10,497		10,497
Cost of common shares in treasury, net
Stockholders' equity:
Treasury stock, value	(525,653)		(525,653)
Cost of common shares in treasury, net | Moving and Storage Consolidations
Stockholders' equity:
Treasury stock, value	(525,653)		(525,653)
Cost of common shares in treasury, net | AMERCO /NV/
Stockholders' equity:
Treasury stock, value	(525,653)		(525,653)
Cost of preferred shares in treasury, net
Stockholders' equity:
Treasury stock, value	(151,997)		(151,997)
Cost of preferred shares in treasury, net | Moving and Storage Consolidations
Stockholders' equity:
Treasury stock, value	(151,997)		(151,997)
Cost of preferred shares in treasury, net | AMERCO /NV/
Stockholders' equity:
Treasury stock, value	$ (151,997)		$ (151,997)

[1] Balances as of March 31, 2012

[2] Balances as of December 31, 2011

[3] Balance for the period ended March 31, 2011

[4] Eliminate intercompany receivables and payables

[5] Eliminate investment in subsidiaries