Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Interest and debt expense:
Weighted average interest rate during the quarter	2.47%	1.82%	2.38%	1.76%
Interest rate at quarter end	2.56%	1.89%	2.56%	1.89%
Maximum amount outstanding during the quarter	$ 535,000	$ 597,000	$ 538,000	$ 597,000
Average amount outstanding during the period	532,261	550,304	516,349	450,880
Facility fees	$ 159	$ 10	$ 284	$ 99