Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
ASSETS:
Cash and cash equivalents	$ 441,850	$ 495,112
Reinsurance recoverables and trade receivables, net	189,869	199,322
Inventories, net	69,472	67,020
Prepaid expenses	126,296	55,269
Investments, fixed maturities and marketable equities	1,304,962	1,138,275
Investments, other	268,720	248,850
Deferred policy acquisition costs, net	115,422	118,707
Other assets	106,157	97,588
Related party assets	141,790	169,624
Subtotal assets	2,764,538	2,589,767
Property, plant and equipment, at cost:
Land	467,482	405,177
Buildings and improvements	1,728,033	1,430,272
Furniture and equipment	355,349	322,146
Property, plant and equipment (gross)	6,047,493	5,141,717
Less: Accumulated depreciation	(1,939,856)	(1,732,506)
Total property, plant and equipment	4,107,637	3,409,211
Total assets	6,872,175	5,998,978
Liabilities:
Accounts payable and accrued expenses	495,135	357,954
Notes, loans and leases payable	2,190,869	1,942,359
Policy benefits and losses, claims and loss expenses payable	1,062,188	1,082,598
Liabilities from investment contracts	685,745	616,725
Other policyholders' funds and liabilities	8,999	7,988
Deferred income	18,081	31,390
Deferred income taxes, net	526,799	432,596
Total liabilities	4,987,816	4,471,610
Commitments and contingencies (notes 9, 16, 17 and 18)
Stockholders' equity:
Additional paid-in capital	449,668	444,210
Accumulated other comprehensive loss	(34,365)	(53,923)
Retained earnings	2,142,600	1,805,453
Unearned employee stock ownership plan shares	(6,391)	(1,219)
Total stockholders' equity	1,884,359	1,527,368
Total liabilities and stockholders' equity	6,872,175	5,998,978
Series A Preferred Stock [Member]
Stockholders' equity:
Preferred stock, value, issued
Series B Preferred Stock [Member]
Stockholders' equity:
Preferred stock, value, issued
Series A Common Stock [Member]
Stockholders' equity:
Common stock, value, issued
Amerco Common Stock [Member]
Stockholders' equity:
Common stock, value, issued	10,497	10,497
Common Stock in Treasury [Member]
Stockholders' equity:
Treasury stock, value	(525,653)	(525,653)
Preferred Stock in Treasury [Member]
Stockholders' equity:
Treasury stock, value	(151,997)	(151,997)
Rental Trailers and Other Rental Equipment [Member]
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	436,642	373,325
Rental Trucks [Member]
Property, plant and equipment, at cost:
Property subject to or available for operating lease, gross	$ 3,059,987	$ 2,610,797