Components of Interest Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Interest expense, borrowings:
Interest expense	$ 17,814	$ 15,646
Capitalized interest	(142)	(77)
Amortization of transaction costs	851	1,085
Interest expense resulting from derivatives	4,805	6,837
Total interest expense	$ 23,328	$ 23,491