Income Taxes - Summary of Income Tax Benefit and Effective Income Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 0.6	$ 8.6	$ (16.8)	$ (7.1)
Income tax (benefit) expense	$ 0.1	$ (2.3)	$ 4.7	$ 1.4
Effective income tax rate	16.70%	26.70%	28.00%	19.70%