Related Party Transactions (Related Party Costs and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Related party cost and expense:
Related party expenses, total	$ 13,667	$ 13,016	$ 47,920	$ 45,621
Sac Holdings [Member]
Related party cost and expense:
U-Haul lease expenses	684	654	2,056	1,962
U-Haul commission expenses	12,135	11,521	42,843	40,780
Private Mini [Member]
Related party cost and expense:
U-Haul commission expenses	$ 848	$ 841	$ 3,021	$ 2,879