Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2021	Feb. 04, 2022
Document and Entity Information [Abstract]
Entity Registrant Name	AMERCO
Entity Central Index Key	0000004457
Entity Current Reporting Status	Yes
Entity Small Business	false
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Document Fiscal Year Focus	2022
Trading Symbol	UHAL
Document Type	10-Q
Document Fiscal Period Focus	Q3
Document Period End Date	Dec. 31, 2021
Amendment Flag	false
Entity Common Stock, Shares Outstanding		19,607,788
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity File Number	001-11255
Entity Tax Identification Number	88-0106815
Entity address, address line one	5555 Kietzke Lane
Entity address, address line two	Suite 100
Entity address, City or Town	Reno
Entity address, State or Province	NV
Entity address, postal zip code	89511
City Area Code	( 775
Local Phone Number	688-6300
Entity Incorporation, State or Country Code	NV
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false