Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Effective income tax rate	15.40%	15.80%
U.S. statutory rate	21.00%	21.00%
Income tax liabilities	$ 264.8		$ 264.8
Gross unrecognized tax benefits	4.3		4.3
Accrued interest and penalties related to unrecognized tax benefits	1.5		$ 1.5
Reasonably possible amount of reduction in gross unrecognized tax benefits for the next twelve months	4.2
Reasonably possible amount of net reduction to income tax provision if unrecognized tax benefits were recognized	$ 5.7