Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024
Available-for-sale Securities [Abstract]
Available for sale investments, allowance for credit loss, net	$ 2,995	$ 1,052
Debt Securities, Available-for-Sale, Amortized Cost, Current	$ 2,631,881	$ 2,660,093
Series Preferred Stock With or Without Par Value [Member]
Preferred stock:
Preferred stock, shares authorized	50,000,000	50,000,000
Series A Preferred Stock [Member]
Preferred stock:
Preferred stock, shares authorized	6,100,000	6,100,000
Preferred stock, shares issued	6,100,000	6,100,000
Series B Preferred Stock [Member]
Preferred stock:
Preferred stock, shares authorized	100,000	100,000
Serial Common Stock With or Without Par Value [Member]
Common stock:
Common stock, shares authorized	250,000,000	250,000,000
Common stock, par or stated value per share	$ 0.25	$ 0.25
Serial Common Stock [Member]
Common stock:
Common stock, shares authorized	10,000,000	10,000,000
Common Stock [Member]
Common stock:
Common stock, shares authorized	250,000,000	250,000,000
Common stock, par or stated value per share	$ 0.25	$ 0.25
Amerco Common Stock [Member]
Common stock:
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares, issued	41,985,700	41,985,700
Common stock, shares, outstanding	19,607,788	19,607,788
Common stock, par or stated value per share	$ 0.25	$ 0.25
Nonvoting Common Stock [Member]
Common stock:
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares, outstanding	176,470,092	176,470,092
Common stock, par or stated value per share	$ 0.001	$ 0.001
Common Stock in Treasury [Member]
Treasury stock:
Treasury Stock Common Shares	22,377,912	22,377,912
Preferred Stock in Treasury [Member]
Treasury stock:
Treasury Stock Common Shares	6,100,000	6,100,000