Interest on Borrowings (Components of interest expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Interest expense, borrowings:
Interest expense	$ 180,444	$ 150,609	$ 125,412
Capitalized interest	(23,517)	(12,733)	(6,466)
Amortization of transaction costs	4,427	3,745	3,867
Interest expense resulting from derivatives	$ (404)	$ 824	$ 3,893