Long-term Debt (Details 4) - USD ($)	9 Months Ended	12 Months Ended
	Jun. 30, 2015	Sep. 30, 2011	Mar. 31, 2015	Sep. 30, 2014
Long-term debt
Debt instrument, face amount	$ 575,000,000			$ 599,800,000
Senior Secured Notes 7.625 Percent
Long-term debt
Interest rate on long-term debt (as a percent)		7.625%	7.625%	7.625%
Debt instrument, face amount		$ 400,000,000		$ 400,000,000
Net proceeds from senior secured notes		$ 392,800,000
Loss on extinguishment of debt	21,300,000
Early repayment premium amount	15,300,000
Early repayment of interest amount	2,500,000
Premiums and accelerated amortization of unamortized debt issue costs charged to interest expense	3,500,000
Convertible Senior Subordinated Notes 8.75 Percent Due 2016
Long-term debt
Interest rate on long-term debt (as a percent)			8.75%	8.75%
Debt instrument, face amount				$ 49,791,000
Premiums and accelerated amortization of unamortized debt issue costs charged to interest expense	$ 3,500,000