Borrowings (Components of Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest expense, borrowings:
Interest expense	$ 36,220	$ 31,863	$ 70,416	$ 61,492
Capitalized interest	(2,227)	(1,929)	(2,646)	(3,694)
Amortization of transaction costs	881	1,014	1,842	1,946
Interest expense resulting from derivatives	156	1,075	672	2,624
Total interest expense	$ 35,030	$ 32,023	$ 70,284	$ 62,368