Condensed Consolidated Balance Sheets Parenthetical - $ / shares	Dec. 31, 2018	Mar. 31, 2018
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
Preferred stock, shares outstanding	0	0
Preferred stock, no par value	$ 0	$ 0
Series B Preferred Stock [Member]
Preferred stock:
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, no par value	$ 0	$ 0
Series Common Stock With or Without Par Value [Member]
Common stock:
Common stock, shares authorized	250,000,000	250,000,000
Series A Common Stock [Member]
Common stock:
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares, issued	0	0
Common stock, shares, outstanding	0	0
Common stock, par or stated value per share	$ 0.25	$ 0.25
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
Common Stock in Treasury [Member]
Treasury stock:
Treasury stock, shares	22,377,912	22,377,912
Preferred Stock in Treasury [Member]
Treasury stock:
Treasury stock, shares	6,100,000	6,100,000