Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Mar. 31, 2014
Carrying Value | Commodity swap / forward
Defined Benefit Plan Disclosure [Line Items]
Derivative Liability	$ (28)	[1]	$ (1,709)	[1]
Carrying Value | Senior Secured Notes
Defined Benefit Plan Disclosure [Line Items]
Debt	(766,070)	[2]	(734,474)	[2]
Carrying Value | Convertible senior subordinated notes
Defined Benefit Plan Disclosure [Line Items]
Debt	(51,900)	[2]	(51,900)	[2]
Estimated Fair Value | Commodity swap / forward
Defined Benefit Plan Disclosure [Line Items]
Derivative Liability	(28)	[1]	(1,709)	[1]
Estimated Fair Value | Senior Secured Notes
Defined Benefit Plan Disclosure [Line Items]
Debt	(199,187)	[2]	(560,955)	[2]
Estimated Fair Value | Convertible senior subordinated notes
Defined Benefit Plan Disclosure [Line Items]
Debt	$ (2,336)	[2]	$ (12,988)	[2]

[1] These financial instruments are required to be measured at fair value, and are based on inputs as described in the three-tier hierarchy that prioritizes inputs used in measuring fair value as of the reported date:

[2] Classified as liabilities subject to compromise