Related Party Transactions (Related Party Costs and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Related party cost and expense:
Related party expenses, total	$ 14,091	$ 13,667	$ 48,889	$ 47,920
Blackwater [Member]
Related party cost and expense:
U-Haul lease expenses	658	684	2,014	2,056
U-Haul commission expenses	$ 13,433	$ 12,983	$ 46,875	$ 45,864