Borrowings (Narratives) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 4,673,383		$ 4,668,907
Debt instruments, issuance and maturity dates:
Remaining Lease Term Finance Lease Weighted Average	14.8		14.7
Interest paid related to derivative contracts [Abstract]
Interest paid in cash	$ 36,100	$ 39,400
Real estate loan [Member]
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2023
Capital Lease Obligations [Member] | AMERCO [Member]
Debt instruments, face, payment, and remaining balance amount:
Capitalized assets, net book value	$ 804,100		$ 865,600
Lease Cost [Abstract]
Sale Leaseback Transaction Lease Terms	(7) year terms
Capital Lease Obligations [Member] | AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.92%
Capital Lease Obligations [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.04%
Finance Lease [Member] | AMERCO [Member]
Lease Cost [Abstract]
Sale Leaseback Transaction Lease Terms	(7) years
Finance Lease [Member] | AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.60%
Finance Lease [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.22%
Amerco Real Estate Subsidiaries and Uhaul Company of Florida [Member] | Real estate loan [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.10%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.60%
Amerco Real Estate Company [Member] | Rental Truck (amortizing loans) First Loan [Member] | AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.61%
Amerco Real Estate Company [Member] | Rental Truck (amortizing loans) First Loan [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.66%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Senior Mortgages [Member]
Debt instruments, interest rate, effective percentage:
Debt Weighted Average Interest Rate	4.27%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Senior Mortgages [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.80%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Senior Mortgages [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	6.62%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Working capital loans two [Member] | AMERCO [Member]
Debt instruments, face, payment, and remaining balance amount:
Line of credit, current borrowing capacity	$ 385,000
Line of credit facility, remaining borrowing capacity	$ 385,000
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Working capital loans two [Member] | AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.08%
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.34%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Working capital loans two [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.09%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.59%
Uhaul Intl and Subsidiaries [Member] | Working capital loans two [Member] | AMERCO [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.09%
Applicable margin interest rate	1.38%
Sum of LIBOR and margin, maximum rate	1.47%
Unused capacity fee	0.30%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 300,000
Line of credit, current borrowing capacity	200,000
Notes, loans and leases payable	$ 150,000
Uhaul Intl and Subsidiaries [Member] | Rental Truck Revolvers [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.36%
Debt instruments, interest rate, effective percentage:
LIBOR	0.09%
Debt instruments, face, payment, and remaining balance amount:
Line of credit, current borrowing capacity	$ 590,000
New capital lease obligiations, amount	535,000
Subsidiary holdings of parent company debt	$ 100,000
Uhaul Intl and Subsidiaries [Member] | Rental Truck Revolvers [Member] | Minimum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.15%
Sum of LIBOR and margin, maximum rate	1.24%
Uhaul Intl and Subsidiaries [Member] | Rental Truck Revolvers [Member] | Maximum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.34%
Amerco, Us Bank, National Association, Trustee [Member] | Other Obligations [Member]
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 89,500
Subsidiary holdings of parent company debt	$ 2,400
Amerco, Us Bank, National Association, Trustee [Member] | Other Obligations [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.75%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2021
Amerco, Us Bank, National Association, Trustee [Member] | Other Obligations [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	8.00%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2049
Life Insurance [Member] | Federal Home Loan Bank [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Aggregate deposit amount			70,500
Available for sale equity securities, noncurrent			134,300
Available for sale equity securities pledged as collateral			$ 79,300
Life Insurance [Member] | Federal Home Loan Bank [Member] | Minimum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			0.00%
Life Insurance [Member] | Federal Home Loan Bank [Member] | Maximum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			1.72%