Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Sep. 30, 2011	Sep. 30, 2010
Long-term debt
Debt instrument, face amount	$ 535,600	$ 543,100
Convertible senior subordinated notes, net of applicable discounts	122,705	127,803
Long-term debt	522,705	527,803
Less current portion	(9,095)	(9,014)
Carrying amount of long-term debt, net of discounts	513,610	518,789
7-5/8% Senior secured notes, due April 2019
Long-term debt
Senior secured notes	400,000	400,000
Interest rate on long-term debt (as a percent)	7.625%
16% Convertible senior subordinated notes due 2016
Long-term debt
Debt instrument, face amount	9,233	9,233
Convertible senior subordinated notes, net of applicable discounts	9,095	9,014
Interest rate on long-term debt (as a percent)	16.00%		16.00%
2.50% Convertible senior subordinated notes due 2014
Long-term debt
Debt instrument, face amount	113,400	120,900
Convertible senior subordinated notes, net of applicable discounts	101,419	106,688
Interest rate on long-term debt (as a percent)	2.50%	2.50%
14.75% Convertible senior subordinated notes due 2014
Long-term debt
Debt instrument, face amount	12,965	12,965
Convertible senior subordinated notes, net of applicable discounts	$ 12,191	$ 12,101
Interest rate on long-term debt (as a percent)	14.75%		14.75%