Borrowings (Narratives) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 6,022,497	$ 4,668,907
Debt instruments, issuance and maturity dates:
Remaining Lease Term Finance Lease Weighted Average	3	3
Minimum [Member]
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2022
Maximum [Member]
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2036
Rental Truck (amortizing loans) First Loan [Member] | Uhaul International, Inc and AMERCO [Member]
Debt instruments, face, payment, and remaining balance amount:
Capitalized assets, net book value	$ 1,068,300	$ 718,300
Lease Cost [Abstract]
Sale Leaseback Transaction Lease Terms	(7) years
Rental Truck (amortizing loans) First Loan [Member] | Uhaul International, Inc and AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.60%
Rental Truck (amortizing loans) First Loan [Member] | Uhaul International, Inc and AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.68%
Capital Lease Obligations [Member] | Amerco Real Estate Co and Uhaul International, Inc [Member]
Debt instruments, face, payment, and remaining balance amount:
Amounts held at LIBOR plus margin	$ 150,000
New capital lease obligations, amount	$ 600,000
Capital Lease Obligations [Member] | Amerco Real Estate Co and Uhaul International, Inc [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.43%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2029
Capital Lease Obligations [Member] | Amerco Real Estate Co and Uhaul International, Inc [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.78%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2033
Finance Lease [Member] | Amerco [Member]
Debt instruments, face, payment, and remaining balance amount:
Capitalized assets, net book value	$ 620,800	$ 877,000
Lease Cost [Abstract]
Sale Leaseback Transaction Lease Terms	(7) year terms
Finance Lease [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.16%
Finance Lease [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.04%
Amerco Real Estate Subsidiaries and Uhaul Company of Florida [Member] | Real estate loan (amortizing term) [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.33%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.83%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Senior mortgages [Member]
Debt instruments, interest rate, effective percentage:
Debt Weighted Average Interest Rate	4.00%
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	2.70%
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	5.50%
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 facility, remaining borrowing capacity	$ 385,000
Notes, loans and leases payable	$ 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	0.21%
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.46%
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	0.45%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.85%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck (amortizing loans) Second Loan [Member] | Uhual International, Inc [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.36%
Debt instruments, interest rate, effective percentage:
LIBOR	0.21%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 590,000
Amounts held at LIBOR plus margin	385,000
Notes, loans and leases payable	560,000
Amount held at fixed interest rate	$ 100,000
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck (amortizing loans) Second Loan [Member] | Uhual International, Inc [Member] | Minimum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.15%
Sum of LIBOR and margin, maximum rate	1.36%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck (amortizing loans) Second Loan [Member] | Uhual International, Inc [Member] | Maximum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.46%
Amerco Real Estate Company [Member] | Real estate loans (revolving credit) [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.21%
Applicable margin interest rate	1.38%
Sum of LIBOR and margin, maximum rate	1.59%
Unused capacity fee	0.30%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 200,000
Amounts held at LIBOR plus margin	300,000
Notes, loans and leases payable	$ 150,000
Uhaul Intl and Subsidiaries [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.61%
Uhaul Intl and Subsidiaries [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.66%
Uhaul Intl and Subsidiaries [Member] | Capital Lease Obligations [Member] | Amerco [Member]
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, remaining borrowing capacity	$ 150,000
New capital lease obligations, amount	600,000
Subsidiary holdings of parent company debt	$ 100,000
Uhaul Intl and Subsidiaries [Member] | Capital Lease Obligations [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.55%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2030
Uhaul Intl and Subsidiaries [Member] | Capital Lease Obligations [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.88%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2035
Amerco, Us Bank, National Association, Trustee [Member] | Other Obligations [Member]
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 88,500
Subsidiary holdings of parent company debt	$ 2,300
Amerco, Us Bank, National Association, Trustee [Member] | Other Obligations [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.50%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2022
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] | FHLB [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit amount			$ 60,000
Available for sale equity securities, noncurrent			105,600
Available for sale equity securities pledged as collateral			$ 62,800
Life Insurance [Member] | FHLB [Member] | Minimum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			0.49%
Life Insurance [Member] | FHLB [Member] | Maximum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			1.72%