Long-term Debt (Details 4) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2014	Mar. 31, 2015	Sep. 30, 2015	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2012	Sep. 30, 2011
Long-term debt
Debt instrument, face amount			$ 573,900		$ 599,800
Loss on extinguishment of debt		$ 24,800
Convertible Senior Subordinated Notes 2.50 Percent Due 2014
Long-term debt
Interest rate on secured notes (as a percent)				2.50%
Repurchase and cancellation of convertible senior subordinated notes	$ 7,700			$ 47,400
Cash consideration paid for cancelation of convertible senior subordinated notes				47,700
Write-off of unamortized balances of debt discount and debt issue costs				$ 2,400
Convertible Senior Subordinated Notes 2.50 Percent Due 2014 | Chairman and CEO
Long-term debt
Convertible senior subordinated notes						$ 1,160
Senior Secured Notes 7.625 Percent
Long-term debt
Interest rate on secured notes (as a percent)					7.625%		7.625%
Debt instrument, face amount					$ 400,000		$ 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%			8.75%
Debt instrument, face amount					$ 49,791
Repurchase and cancellation of convertible senior subordinated notes			49,000
Premiums and accelerated amortization of unamortized debt issue costs charged to interest expense			$ 3,500