Borrowings (Narratives) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 4,777,963		$ 4,621,291
Debt instruments, issuance and maturity dates:
Remaining Lease Term Finance Lease Weighted Average	4
Interest paid related to derivative contracts [Abstract]
Interest paid in cash	$ 39,400	$ 40,500
Real estate loan [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.18%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.68%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2023
Real estate loans (revolving credit) [Member] | AMERCO [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	1.00%
Applicable margin interest rate	2.25%
Sum of LIBOR and margin, maximum rate	3.25%
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
Line of credit facility, remaining borrowing capacity	$ 150,000
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] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.63%
Finance Lease [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.22%
Other Obligations [Member] | AMERCO [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.50%
Applicable margin interest rate	2.00%
Debt instrument, interest rate at period end	0.50%
Sum of LIBOR and margin, maximum rate	2.50%
Debt instruments, face, payment, and remaining balance amount:
Debt instrument, face amount	$ 200,000
Line of credit facility increase, amount	$ 200,000
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2021
Amerco Real Estate Company [Member] | Working capital loans two [Member] | AMERCO [Member]
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 385,000
Notes, loans and leases payable	$ 385,000
Amerco Real Estate Company [Member] | Working capital loans two [Member] | AMERCO [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	3.03%
Debt instruments, interest rate, effective percentage:
LIBOR	0.17%
Applicable margin interest rate	1.25%
Sum of LIBOR and margin, maximum rate	1.42%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2022
Amerco Real Estate Company [Member] | Working capital loans two [Member] | AMERCO [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	3.14%
Debt instruments, interest rate, effective percentage:
LIBOR	0.18%
Applicable margin interest rate	1.50%
Sum of LIBOR and margin, maximum rate	1.67%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2025
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	3.11%
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] | Rental Truck Revolvers [Member]
Debt instruments, interest rate, effective percentage:
LIBOR	0.17%
Applicable margin interest rate	1.15%
Sum of LIBOR and margin, maximum rate	1.32%
Debt instruments, face, payment, and remaining balance amount:
Line of credit facility, maximum borrowing capacity	$ 590,000
Uhaul Intl and Subsidiaries [Member] | Rental Truck (amortizing loans) First Loan [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.04%
Uhaul Intl and Subsidiaries [Member] | Rental Truck (amortizing loans) First Loan [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.66%
Amerco, Us Bank, National Association, Trustee [Member] | Uhaul International, Inc [Member]
Debt instruments, face, payment, and remaining balance amount:
Notes, loans and leases payable	$ 85,200
Subsidiary holdings of parent company debt	$ 2,700
Amerco, Us Bank, National Association, Trustee [Member] | Uhaul International, Inc [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.50%
Debt instruments, issuance and maturity dates:
Debt instrument, maturity year	2020
Amerco, Us Bank, National Association, Trustee [Member] | Uhaul International, Inc [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	$ 60,000
Available for sale equity securities, noncurrent	191,400
Available for sale equity securities pledged as collateral	$ 69,500
Life Insurance [Member] | Federal Home Loan Bank [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	0.69%
Life Insurance [Member] | Federal Home Loan Bank [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.95%