Income Taxes - Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Domestic	$ (39.0)	$ (116.7)	$ (100.9)
Foreign	175.3	160.9	206.6
Income Before Income Taxes	$ 136.3	$ 44.2	$ 105.7