Interest on Borrowings (Components of interest expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Interest expense, borrowings:
Interest expense	$ 85,592	$ 80,905	$ 72,538
Capitalized interest	(3,623)	(1,204)	(571)
Amortization of transaction costs	3,235	3,495	3,551
Interest expense resulting from derivatives	12,699	14,329	17,174
Total interest expense	$ 97,903	97,525	$ 92,692
Write-off of transaction costs related to early extinguishment of debt		298
Fees on early extinguishment of debt		3,783
Fees and amortization of early extinguishment of debt		4,081
Total	$ 97,903	$ 101,606	$ 92,692