Income Taxes - Schedule of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Current
Federal	$ 9.4	$ (0.9)	$ (14.4)
State	4.3	2.1	(2.6)
Non-U.S.	3.0	1.8	1.7
Current income tax expense	16.7	3.0	(15.3)
Deferred
Federal	16.2	47.7	43.8
State	1.3	9.0	24.8
Non-U.S.	0.5	0.2	0.1
Deferred income tax expense	18.0	56.9	68.7
Income tax expense	$ 34.7	$ 59.9	$ 53.4