Liabilities (Details 6) (USD $)	12 Months Ended			1 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2011 11-3/8% senior secured notes	Sep. 30, 2012 11-3/8% senior secured notes
Liabilities
Interest expense	$ 53,400,000	$ 127,000,000	$ 72,400,000
Non-cash interest expense	14,184,000	20,069,000	16,027,000
Capitalized interest costs	100,000	100,000	400,000
Interest income	200,000	300,000	300,000
Weighted average interest rate (as a percent)	7.20%	6.80%
Long-term debt
Debt instrument early repayment premium		$ 62,600,000		$ 59,000,000
Interest rate on long-term debt (as a percent)				11.375%	11.375%