Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Income Taxes
Effective income tax rate (as a percent)	35.20%	36.80%
Effective income tax rates as compared to the U.S. Federal income tax rate
U.S. Federal income tax rate (as a percent)	35.00%
Reasonably possible increase in the reserve for uncertain tax positions, low range	$ 7.0
Reasonably possible increase in the reserve for uncertain tax positions, high range	$ 10.0