Borrowings (Components of Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest expense, borrowings:
Interest expense	$ 31,863	$ 25,879	$ 61,492	$ 49,964
Capitalized interest	(1,929)	(985)	(3,694)	(2,298)
Amortization of transaction costs	1,014	804	1,946	1,647
Interest expense resulting from derivatives	1,075	2,291	2,624	5,102
Total interest expense	$ 32,023	$ 27,989	$ 62,368	$ 54,415