Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Effective income tax rate	27.40%	22.50%	27.40%	24.10%
U.S. statutory rate			35.00%
Gross unrecognized tax benefits	$ 42.5		$ 42.5		$ 40.8
Accrued interest and penalties related to unrecognized tax benefits	9.8		9.8		12.4
Net reduction of income tax provision related to unrecognized tax benefits, tax penalties, accrued interest and offsetting tax assets	26.4		26.4
Reasonably possible amount of decrease in gross unrecognized tax benefits for the next twelve months	$ 32.3		$ 32.3