Long-term Debt - Senior Secured and Convertible Subordinated Notes (Details) - USD ($) $ in Thousands	1 Months Ended
	Mar. 31, 2015	Feb. 28, 2015	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2011
Long-term debt
Debt instrument, face amount			$ 568,100	$ 573,900
Senior Secured Notes 7.625 Percent
Long-term debt
Interest rate on secured notes (as a percent)	7.625%		7.625%		7.625%
Debt instrument, face amount					$ 400,000
Loss on extinguishment of debt	$ 21,300
Early repayment premium amount	15,300
Early repayment of interest amount	2,500
Premiums and accelerated amortization of unamortized debt issue costs charged to interest expense	$ 3,500
Convertible Senior Subordinated Notes 8.75 Percent Due 2016
Long-term debt
Interest rate on secured notes (as a percent)		8.75%
Repurchase and cancellation of senior notes		$ 49,000
Premiums and accelerated amortization of unamortized debt issue costs charged to interest expense		3,500
Convertible Senior Subordinated Notes 8.75 Percent Due 2016 | Chairman and CEO
Long-term debt
Convertible senior subordinated notes		$ 1,160