Interest (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Interest
Gross interest	$ 62,961	$ 66,527	$ 74,765
Deferred charges amortization	3,354	3,411	3,942
Capitalized interest		(2,928)	(4,077)
Total	$ 66,315	$ 67,010	$ 74,630