Commitments and Contingencies (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2010	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Cash performance unit awards
Commitments and Contingencies
Performance period	6 months			5 years
Amount of free cash flow performance goals				$ 850.0
Amount of free cash flow achieved		319.2
Amount of free cash flow expenses accrued		4.0
Amount of free cash flow expenses accrued and unpaid		3.3
Maximum payout		1.4
Percentage of performance units vested		50.00%	50.00%
Average stock price period immediately preceding each vest date		60 days
Expense related solely to increase (decrease) in average stock price		1.7	(1.1)
Amount recorded for 2012 performance unit award grants		9.6
SARs - 2011 Awards
Commitments and Contingencies
Grants approved by committee to employees for cash settled stock appreciation rights (in shares)			0.4
Amount accrued for awards		0.8
Grant-date stock price (in dollars per share)		$ 3.81
Ending period for expected liability adjustment		September 30, 2015
SARs - 2012 Awards
Commitments and Contingencies
Average stock price period immediately preceding each vest date		60 days
Grants approved by committee to employees for cash settled stock appreciation rights (in shares)		1.0
Amount accrued for awards		2.8
Ending period for expected liability adjustment		September 30, 2016
Percentage of stock price on grant date		135.00%
Price at grant date		$ 2.50
Average closing stock price (in dollars per share)		$ 1.85
Employment Agreements
Commitments and Contingencies
Compensation arrangements original term of employment agreements, maximum		3 years
Employee agreement terms		1 year
Aggregate salary commitment under all employment agreements assuming no agreements are renewed		3.3
Percentage of CEO salary		42.50%
Aggregate termination benefits		5.1
Employment Agreements | Minimum
Commitments and Contingencies
Annual salaries under employment agreements		0.1
Employment Agreements | Maximum
Commitments and Contingencies
Annual salaries under employment agreements		0.7
Executive Change In Control Agreements
Commitments and Contingencies
Aggregate value of severance payments and excess of market value of stock-based awards		$ 22.1