Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2014 7-5/8% Senior secured notes, due April 2019	Sep. 30, 2013 7-5/8% Senior secured notes, due April 2019	Sep. 30, 2011 7-5/8% Senior secured notes, due April 2019	Mar. 31, 2014 Convertible senior subordinated notes	Sep. 30, 2013 Convertible senior subordinated notes	Mar. 31, 2014 2.50% Convertible senior subordinated notes due February 2014	Sep. 30, 2013 2.50% Convertible senior subordinated notes due February 2014	Mar. 31, 2014 8.75% Convertible senior subordinated notes due February 2016	Sep. 30, 2013 8.75% Convertible senior subordinated notes due February 2016	Mar. 31, 2014 71/4% Senior notes, due January 2019	Dec. 31, 2013 71/4% Senior notes, due January 2019	Sep. 30, 2013 71/4% Senior notes, due January 2019
Long-term debt
Debt instrument, face amount	$ 599,800	$ 457,500						$ 7,687	$ 7,687	$ 49,791	$ 49,791
Carrying amount of long-term debt, net of discounts	599,500	456,973	400,000	400,000		49,500	56,973	0	7,553	49,500	49,420	150,000		0
Less current portion	0	(7,553)
Long-term debt	$ 599,500	$ 449,420
Interest rate on long-term debt (as a percent)			7.625%	7.625%	7.625%			2.50%	2.50%	8.75%	8.75%	7.25%	7.25%	7.25%