Certain Balance Sheet Information Certain Balance Sheet Information - Components of Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Finite-Lived Intangible Assets [Line Items]
Less: accumulated amortization	$ 14.2	$ 19.7
Total intangible assets, net	29.3	27.3
Amortization of intangible assets and interest expense	3.3	2.9	3.7
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	38.3	39.5
Less: accumulated amortization	(13.4)	(12.7)
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	0	7.5
Less: accumulated amortization	0	(7.0)
Deferred Financing And Other Costs [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	5.2	0
Less: accumulated amortization	$ (0.8)	$ 0