Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Interest and debt expense:
Weighted average interest rate during the quarter	1.82%	1.66%	1.76%	1.65%
Interest rate at quarter end	1.89%	1.69%	1.89%	1.69%
Maximum amount outstanding during the quarter	$ 597,000	$ 265,000	$ 597,000	$ 265,000
Average amount outstanding during the period	550,304	258,207	450,880	224,582
Facility fees	$ 10	$ 25	$ 99	$ 169