Schedule I - Condensed Financial Information of AMERCO Balance Sheets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
ASSETS:
Cash and cash equivalents	$ 463,744	$ 357,180	$ 382,514	$ 244,118
Related party assets	182,035	316,157
Total assets	5,306,601	4,654,051	4,191,433
Liabilities:
Other Liabilities	4,077,342	3,618,231
Stockholders' equity:
Additional paid-in capital	438,168	433,743
Accumulated other comprehensive loss	(22,680)	(45,436)
Consolidated statement of change in equity
Beginning of period	1,317,064
Adjustment to initially apply ASU 2010-26	(1,721)
Net earnings	264,708	205,367	183,575
Excess of redemption value over carrying value of preferred shares redeemed		(5,908)	(178)
Net activity	193,439	42,800	180,109
Retained earnings, end of period	1,482,630	1,317,064
Total stockholders' equity	1,229,259	1,035,820
Total liabilities and stockholders' equity	5,306,601	4,654,051
Series A preferred stock
Stockholders' equity:
Preferred stock
Series B preferred stock
Stockholders' equity:
Preferred stock
Series A common stock
Stockholders' equity:
Common stock
Common stock
Stockholders' equity:
Common stock	10,497	10,497
Cost of common shares in treasury, net
Consolidated statement of change in equity
Cost of shares in treasury	(525,653)	(525,653)
Cost of preferred shares in treasury, net
Consolidated statement of change in equity
Cost of shares in treasury	(151,997)	(151,997)
AMERCO
ASSETS:
Cash and cash equivalents	327,119	201,502	250,104	100,460
Investments in subsidiaries	240,080	8,168
Related party assets	1,032,124	1,201,385
Other assets	43,841	27,030
Total assets	1,643,164	1,438,085
Liabilities:
Other Liabilities	412,199	399,867
Stockholders' equity:
Additional paid-in capital	438,378	433,953
Accumulated other comprehensive loss	(22,680)	(45,436)
Consolidated statement of change in equity
Beginning of period	1,316,854	1,139,792
Adjustment to initially apply ASU 2010-26	(1,721)	0
Net earnings	264,708	205,695	184,126
Excess of redemption value over carrying value of preferred shares redeemed	0	(5,908)	0
Dividends	(97,421)	(22,725)
Net activity	165,566	177,062
Retained earnings, end of period	1,482,420	1,316,854	1,139,792
Total stockholders' equity	1,230,965	1,038,218
Total liabilities and stockholders' equity	1,643,164	1,438,085
AMERCO | Series A preferred stock
Stockholders' equity:
Preferred stock	0	0
AMERCO | Series B preferred stock
Stockholders' equity:
Preferred stock	0	0
AMERCO | Series A common stock
Stockholders' equity:
Common stock	0	0
AMERCO | Common stock
Stockholders' equity:
Common stock	10,497	10,497
AMERCO | Cost of common shares in treasury, net
Consolidated statement of change in equity
Cost of shares in treasury	(525,653)	(525,653)
AMERCO | Cost of preferred shares in treasury, net
Consolidated statement of change in equity
Cost of shares in treasury	$ (151,997)	$ (151,997)