Related Party Transactions (Related Party Costs and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Related party cost and expense:
Related party expenses, total	$ 18,231	$ 17,812	$ 34,798	$ 34,253
Blackwater [Member]
Related party cost and expense:
U-Haul lease expenses	675	684	1,356	1,372
U-Haul commission expenses	$ 17,556	$ 17,128	$ 33,442	$ 32,881