Components of Interest Expense (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Interest expense, borrowings:
Interest expense	$ 72,538	$ 66,159	$ 63,523
Capitalized interest	(571)	(415)	(221)
Amortization of transaction costs	3,551	4,133	4,428
Interest expense resulting from derivatives	17,174	20,819	22,641
Total interest expense	$ 92,692	$ 90,696	$ 90,371