Income Taxes - Summary of Income Tax Expense(Benefit) and Effective Income Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 8.7	$ 47.0	$ (5.9)	$ 24.9
Income tax expense (benefit)	$ 2.3	$ 13.3	$ (1.9)	$ 7.6
Effective income tax rate	26.40%	28.30%	32.20%	30.50%