Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Foreign Currency Forwards [Member]
Defined Benefit Plan Disclosure [Line Items]
Derivative Assets	$ 0	$ 25
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commodity swaps [Member]
Defined Benefit Plan Disclosure [Line Items]
Derivative Assets	0	141
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Senior Secured Notes Due 2018 [Member]
Defined Benefit Plan Disclosure [Line Items]
Long-term Debt, Fair Value	(675,000)	(675,000)
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Convertible Senior Subordinated Notes due 2013 [Member]
Defined Benefit Plan Disclosure [Line Items]
Long-term Debt, Fair Value	(51,900)	(55,750)
Estimate of Fair Value, Fair Value Disclosure [Member] | Foreign Currency Forwards [Member]
Defined Benefit Plan Disclosure [Line Items]
Derivative Assets	0	25
Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity swaps [Member]
Defined Benefit Plan Disclosure [Line Items]
Derivative Assets	0	141
Estimate of Fair Value, Fair Value Disclosure [Member] | Senior Secured Notes Due 2018 [Member]
Defined Benefit Plan Disclosure [Line Items]
Long-term Debt, Fair Value	(488,531)	(580,500)
Estimate of Fair Value, Fair Value Disclosure [Member] | Convertible Senior Subordinated Notes due 2013 [Member]
Defined Benefit Plan Disclosure [Line Items]
Long-term Debt, Fair Value	$ (8,434)	$ (52,864)