Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Effective tax rate (as percent)	13.40%	19.50%
Tax at federal statutory rate (as percent)	21.00%	21.00%
Tax benefit related to deferred tax assets resulting from legal entity restructuring	$ 20.1
Tax benefit related to income tax credits and incentives	17.6	$ 13.0
Tax expense related to foreign residual income	15.1	11.3
Tax expense related to state income taxes	6.1	4.2
Tax expense related to valuation allowances		4.4
Deferred tax assets resulting from legal entity restructuring	20.1
Tax expense related to audit settlement		$ 6.9
Gross book-tax differences from non-U.S. subsidiaries	$ 1,200.0