Debt - Interest Income and Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Interest expense
Contractual interest expense	$ 39,087	$ 38,953	$ 38,918
Interest Costs Capitalized	(509)	(237)	(1,552)
Amortization of debt issuance costs	1,392	1,480	1,704
Amortization of debt (premium) discount	(745)	(407)	105
Amortization of Acquisition Costs	212	741	1,787
Capital Leases, Income Statement, Interest Expense	168	171	0
Total interest expense	$ 39,605	$ 40,701	$ 40,962