Long-term Debt (Details 4) (USD $)	6 Months Ended		1 Months Ended			1 Months Ended			3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011 2.50% Convertible senior subordinated notes due 2014	Mar. 31, 2012 2.50% Convertible senior subordinated notes due 2014	Sep. 30, 2011 2.50% Convertible senior subordinated notes due 2014	Nov. 30, 2010 16% Convertible senior subordinated notes due 2016	Mar. 31, 2012 16% Convertible senior subordinated notes due 2016	Sep. 30, 2011 16% Convertible senior subordinated notes due 2016	Mar. 31, 2012 14.75% Convertible senior subordinated notes due 2014	Sep. 30, 2011 14.75% Convertible senior subordinated notes due 2014
Long-term debt
Interest rate on secured notes (as a percent)				2.50%	2.50%	16.00%	16.00%	16.00%	14.75%	14.75%
Repurchase and cancellation of convertible senior subordinated notes			$ 7,500,000			$ 10,000,000
Debt instrument prepayment premium						1,700,000			1,600,000
Debt discount and debt issue costs charged to interest expense			900,000			600,000			700,000
Gain on extinguishment of debt	2,025,000	0	2,000,000
Cash consideration paid for cancelation of convertible senior subordinated notes			$ 5,500,000