Borrowings (Narratives) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 4,668,907	$ 4,621,291
Debt instruments, issuance and maturity dates:
Remaining Lease Term Finance Lease Weighted Average	3	4
Real estate loan (amortizing term) [Member] | Minimum [Member]
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2021
Real estate loan (amortizing term) [Member] | Maximum [Member]
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2036
Rental Truck (securitizations) [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.61%
Rental Truck (securitizations) [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.66%
Capital Lease Obligations [Member] | Amerco [Member]
Lease Cost [Abstract]
Sale Leaseback Transaction Lease Terms	(7) years
Capital Lease Obligations [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.60%
Capital Lease Obligations [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.22%
Finance Lease [Member] | Amerco [Member]
Debt instruments, face, payment, and remaining balance amount:
Capitalized assets, net book value	$ 865,600	$ 1,067,300
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	1.92%
Finance Lease [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.04%
Other Obligations [Member] | Amerco [Member]
Debt instruments, face, payment, and remaining balance amount:
Amounts held at LIBOR plus margin	$ 200,000
Amerco Real Estate Subsidiaries and Uhaul Company of Florida [Member] | Real estate loan (amortizing term) [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.11%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.61%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Senior mortgages [Member]
Debt instruments, interest rate, effective percentage:
Debt Weighted Average Interest Rate	4.28%
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] | Real estate loans (revolving credit) [Member] | Amerco [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.11%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 385,000
Notes, loans and leases payable	$ 385,000
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Real estate loans (revolving credit) [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.36%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Real estate loans (revolving credit) [Member] | Amerco [Member] | Maximum [Member]
Debt instruments, interest rate, effective percentage:
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.61%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck Revolvers [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.36%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 590,000
Notes, loans and leases payable	535,000
Amount held at fixed interest rate	$ 100,000
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck Revolvers [Member] | Minimum [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.11%
Applicable margin interest rate	1.15%
Sum of LIBOR and margin, maximum rate	1.27%
Various Subsidiaries of Amerco Real Estate and Uhaul Intl [Member] | Rental Truck Revolvers [Member] | Maximum [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.12%
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.36%
Amerco Real Estate Company [Member] | Working capital loans two [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.11%
Applicable margin interest rate	1.38%
Sum of LIBOR and margin, maximum rate	1.49%
Unused capacity fee	0.30%
Debt instruments, face, payment, and remaining balance amount:
Aggregate borrowing capacity, amount	$ 200,000
Line of credit facility, maximum borrowing capacity	300,000
Line of credit facility, remaining borrowing capacity	150,000
Amerco, Us Bank, National Association, Trustee [Member] | Amerco [Member]
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	88,600
Subsidiary holdings of parent company debt	$ 2,500
Amerco, Us Bank, National Association, Trustee [Member] | Amerco [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.25%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2021
Amerco, Us Bank, National Association, Trustee [Member] | Amerco [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			$ 70,500
Available for sale equity securities, noncurrent			153,700
Available for sale equity securities pledged as collateral			$ 78,800
Life Insurance [Member] | FHLB [Member] | Minimum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			0.00%
Life Insurance [Member] | FHLB [Member] | Maximum [Member]
Federal Home Loan Bank, Advances, Activity for the year [Abstract]
Deposit interest rate			2.67%