Interest on Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Interest and debt expense:
Weighted average interest rate during the year	3.93%	1.40%	1.40%
Interest rate at year end	5.89%	1.49%	1.40%
Maximum amount outstanding during the year	$ 1,105,000	$ 1,105,000	$ 1,175,000
Average amount outstanding during the year	824,211	1,085,074	1,088,293
Facility fees	$ 733	$ 253	$ 261