Long-term Debt Borrowings, Text Portion (Details) (USD $)			9 Months Ended
	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2012 Amerco Real Estate, Subsidiaries, and U-Haul Co. of Florida Mortgages U-Haul Guarantor	Dec. 31, 2012 Amerco Real Estate, Subsidiaries, and U-Haul Co. of Florida Line of Credit U-Haul Guarantor	Dec. 31, 2012 Amerco Real Estate and Subsidiaries of U-Haul Int'l Construction Loans U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 Amerco Real Estate and U-Haul Company of Florida Line of Credit U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 Various Subsidiaries of Amerco Real Estate and U-Haul Int'l Senior Mortgage Amerco Real Estate and U-Haul Int'l Guarantor	Dec. 31, 2012 Amerco Real Estate Company Capital Lease Obligations U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 U-Haul Int'l and Subsidiaries Rental Truck (Amortizing Credit) First Loan U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 U-Haul Int'l and Subsidiaries Rental Truck (Amortizing Credit) Second Loan U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 Subsidiaries of U-Haul Int'l Cargo Van and Pickup Acquisitions U-Haul Int'l and Amerco Guarantor	Dec. 31, 2012 U-Haul S Fleet 2007 Box Truck Note Securitization First Loan	Dec. 31, 2012 U-Haul S Fleet 2010 Box Truck Note Securitization Second Loan	Dec. 31, 2012 Amerco Capital Leases for New Equipment	Dec. 31, 2012 Amerco and US Bank, National Association, the Trustee U-Haul Investor Club
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage			6.93%									5.56%	4.90%
Debt instrument, interest rate, stated percentage rate range, minimum				1.50%			4.90%		1.75%	2.59%	3.52%				3.00%
Debt instrument, interest rate, stated percentage rate range, maximum				2.00%			5.75%		6.92%	3.94%	3.53%				8.00%
Debt instruments, interest rate, effective percentage:
LIBOR			0.22%		0.21%				0.21%
LIBOR - highest rate									0.22%
Applicable margin interest rate			1.50%		1.90%	1.25%		1.25%
Debt instrument, interest rate at period end					2.11%
Applicable margin, per loan agreement, minimum rate			1.72%						0.90%
Applicable margin, per loan agreement, maximum rate									2.63%
Applicable margins, low rate									0.90%
Applicable margins, high rate									2.63%
Debt instruments, face, payment, and remaining balance amount:
Debt instrument, face amount			$ 300,000,000								$ 115,000,000
Debt instrument, original face amount											85,000,000
Debt instrument, increase in face amount											95,000,000
Debt instrument, associate another note amount											20,000,000
Line of credit facility, maximum borrowing capacity				178,000,000	26,000,000	100,000,000		25,000,000				217,000,000	155,000,000
Line of credit facility, remaining borrowing capacity				178,000,000		100,000,000		25,000,000
Notes, loans and leases payable	1,667,008,000	1,486,211,000	237,500,000		24,800,000		560,800,000		245,700,000	31,100,000		84,600,000	111,600,000	274,400,000	19,000,000
Subsidiary holdings of parent company debt															$ 6,000,000
Debt instruments, issuance and maturity dates:
Mortgage loans on real estate, final maturity date			Aug. 10, 2018	Aug. 10, 2018	Jun. 30, 2016	Apr. 30, 2013
Debt instrument, maturity date								Nov. 30, 2013			Aug. 26, 2016	Feb. 25, 2014	Oct. 25, 2017
Debt instrument, maturity date range, start							Jul. 01, 2015		Jul. 31, 2013	Jul. 31, 2013					Jun. 30, 2013
Debt instrument, maturity date range, end							Oct. 11, 2038		Jan. 31, 2020	Jan. 31, 2020					May 31, 2042
Debt instrument, issuance date					Jun. 29, 2006	Apr. 29, 2011					Dec. 31, 2009	Jun. 01, 2007	Oct. 28, 2010		Feb. 28, 2011
Loan modification and extension date					Jun. 27, 2011	Mar. 31, 2012		Mar. 31, 2012			May 31, 2017
Term note amended date											Aug. 26, 2011
Debt instrument, earliest issuance date														Apr. 29, 2008
Debt instrument, latest issuance date											Dec. 22, 2011			Dec. 31, 2012
Purchase equipment through fiscal year												2008
Debt instruments, miscellaneous information:
Terms of lease														Between 5 and 7 years