Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Income Taxes
Effective income tax rate (as a percent)	38.80%	34.10%
Effective income tax rates as compared to the U.S. Federal income tax rate
U.S. federal statutory rate (as a percent)	35.00%
Uncertain tax positions
Reasonably possible increase in the reserve for uncertain tax positions, low range	$ 8.4
Reasonably possible increase in the reserve for uncertain tax positions, high range	$ 11.0