Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2013 7-5/8% Senior secured notes, due April 2019	Sep. 30, 2012 7-5/8% Senior secured notes, due April 2019	Mar. 31, 2011 7-5/8% Senior secured notes, due April 2019	Mar. 31, 2013 Convertible senior subordinated notes	Sep. 30, 2012 Convertible senior subordinated notes	Mar. 31, 2013 2.50% Convertible senior subordinated notes due February 2014	Sep. 30, 2012 2.50% Convertible senior subordinated notes due February 2014	Dec. 31, 2011 2.50% Convertible senior subordinated notes due February 2014	Mar. 31, 2013 8.75% Convertible senior subordinated notes due February 2016	Sep. 30, 2012 8.75% Convertible senior subordinated notes due February 2016	Mar. 31, 2012 14.75% Convertible senior subordinated notes due 2014
Long-term debt
Debt instrument, face amount	$ 489,600	$ 504,900						$ 39,825	$ 55,077		$ 49,791	$ 49,791
Long-term debt	487,426	500,539	400,000	400,000		87,426	100,539	38,085	51,278		49,341	49,261
Carrying amount of long-term debt, net of discounts	449,341	500,539
Less current portion	$ (38,085)	$ 0
Interest rate on long-term debt (as a percent)			7.625%	7.625%	7.625%			2.50%	2.50%	2.50%	8.75%	8.75%	14.75%