Long-term Debt (Details 4) (USD $)	3 Months Ended		6 Months Ended		23 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Jan. 31, 2016	Sep. 30, 2013
Long-term Debt
Interest expense	$ 12,400,000	$ 11,200,000	$ 22,600,000	$ 21,700,000
Non-cash interest expense	600,000	1,900,000	1,153,000	3,165,000
Weighted average interest rate (as a percent)	7.60%		7.60%			7.70%
Long-term debt
Amount of debt due to mature during a specified period					0
Convertible senior subordinated notes
Long-term debt
Amount of changes in debt			$ 0
2.50% Convertible senior subordinated notes due February 2014
Long-term debt
Interest rate on long-term debt (as a percent)	2.50%		2.50%			2.50%