Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Effective income tax rate	14.50%	16.10%	16.10%	17.80%
Income tax liabilities	$ 97.4		$ 97.4		$ 175.3
Gross unrecognized tax benefits	17.0		17.0		9.8
Accrued interest and penalties related to unrecognized tax benefits	1.2		1.2		$ 0.9
Reasonably possible amount of reduction in gross unrecognized tax benefits for the next twelve months	2.3		2.3
Reasonably possible amount of net reduction to income tax provision if unrecognized tax benefits were recognized	$ 3.1		$ 3.1