Related Party Transactions (Related Party Assets) (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Mar. 31, 2016
Related party assets:
U-Haul receivables		$ 3,649	$ 3,745
Related party assets		86,168	85,734
Sac Holdings [Member]
Related party assets:
Notes receivable		48,098	49,322
U-Haul interest receivable		5,397	4,970
U-Haul receivables		23,202	23,127
Mercury [Member]
Related party assets:
U-Haul receivables		9,195	8,016
Insurance Subsidiaries [Member]
Related party assets:
Other	[1]	$ 276	$ 299

[1] Timing differences for intercompany balances with insurance subsidiaries resulting from the three month difference in reporting periods