Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Sep. 30, 2011
Income Taxes
Effective income tax rate (as a percent)	29.70%	24.10%	29.40%
U.S. federal statutory tax rate (as a percent)			35.00%
Reduction in uncertain tax positions resulting from closing of tax statutes and settlement of various tax uncertainties	$ 2.5		$ 2.5
Unrecognized tax benefits, exclusive of interest	8.3		8.3	10.7
Unrecognized tax benefits that, if recognized, would favorably impact the effective tax rate	6.3		6.3
Effect on unrecognized tax benefits of resolution of reviews by taxing authorities			$ 4.5