Document and Entity Information (USD $)	6 Months Ended
	Sep. 30, 2013
Document and Entity Information [Abstract]
Entity Registrant Name	AMERCO /NV/
Entity Central Index Key	0000004457
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Public Float	$ 902,836,527
Document Fiscal Year Focus	2014
Document Type	10-Q
Document Fiscal Period Focus	Q2
Document Period End Date	Sep. 30, 2013
Amendment Flag	false
Entity Common Stock, Shares Outstanding	19,607,788