Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	16.70%	21.70%
U.S. statutory rate	35.00%	35.00%
Gross unrecognized tax benefits	$ 37.4		$ 32.4
Accrued interest and penalties related to unrecognized tax benefits	5.3		$ 5.2
Reasonably possible amount of reduction in gross unrecognized tax benefits for the next twelve months	15.4
Reasonably possible amount of net reduction to income tax provision if unrecognized tax benefits were recognized	$ 7.8
Earliest open year for income tax examinations, U.S. federal	2014
Earliest open tax year for income tax examinations, state, local and non-U.S.	2003