Income Taxes - Summary of Income Tax Benefit and Effective Income Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 47.0	$ (29.7)	$ 24.9	$ (54.1)
Income tax expense (benefit)	$ 13.3	$ (7.7)	$ 7.6	$ (13.2)
Effective income tax rate	28.30%	25.90%	30.50%	24.40%