Long-term Debt (Details 2) (USD $) In Millions, unless otherwise specified	1 Months Ended			1 Months Ended	9 Months Ended		9 Months Ended
	Mar. 31, 2011 7-5/8% Senior secured notes	Jun. 30, 2012 7-5/8% Senior secured notes	Sep. 30, 2011 7-5/8% Senior secured notes	Mar. 31, 2011 11-3/8% senior secured notes	Jun. 30, 2011 11-3/8% senior secured notes	Jun. 30, 2012 11-3/8% senior secured notes	Jun. 30, 2012 Period commencing after March 31, 2015 Maximum 7-5/8% Senior secured notes	Jun. 30, 2012 Period commencing after March 31, 2015 Minimum 7-5/8% Senior secured notes	Jun. 30, 2012 On or prior to March 31, 2014 7-5/8% Senior secured notes	Jun. 30, 2012 Any 12-month period ending on or prior to March 31, 2014 7-5/8% Senior secured notes	Jun. 30, 2012 On or prior to March 31, 2015 7-5/8% Senior secured notes
Long-term debt
Interest rate on secured notes (as a percent)	7.625%	7.625%	7.625%	11.375%		11.375%
Additional borrowings	$ 400.0
Net proceeds from senior secured notes	392.8
Debt instrument prepayment premium				59.0	59.0
Write off of unamortized balances of debt discount				2.2
Write off of debt issuance cost				6.6
Banking fees				$ 1.1
Debt instrument redemption price (as a percent)							103.80%	100.00%		103.00%
Percentage of the principal amount of the debt instrument which the entity may redeem with proceeds from qualified equity offerings							35.00%			10.00%
Redemption price of debt instrument if redeemed with proceeds from qualified equity offerings (as a percent)									107.60%
Debt instrument redemption price in addition to a make-whole premium (as a percent)											100.00%