Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Interest and debt expense:
Weighted average interest rate during the quarter	1.38%	1.66%	1.38%	1.65%
Interest rate at quarter end	1.39%	1.65%	1.39%	1.65%
Maximum amount outstanding during the quarter	$ 1,085,000	$ 1,082,000	$ 1,093,000	$ 1,175,000
Average amount outstanding during the quarter	1,081,283	1,057,380	1,081,571	1,092,382
Facility fees	$ 66	$ 91	$ 198	$ 185