Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest and debt expense:
Weighted average interest rate during the quarter	1.63%	1.76%	1.64%	1.76%
Interest rate at quarter end	1.63%	1.61%	1.63%	1.61%
Maximum amount outstanding during the quarter	$ 250,000	$ 232,000	$ 250,000	$ 232,000
Average amount outstanding during the period	234,348	202,977	207,678	172,740
Facility fees	$ 50	$ 81	$ 144	$ 198