Income Taxes - Schedule of Income Tax Expense (Benefit) Differs from Amount Computed at Federal Statutory Corporate Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Federal tax at statutory rate	$ 20.3	$ (0.7)	$ 4.1
State tax, net of federal tax (benefit) expense	4.8	(0.8)	1.2
Tax effect of:
Equity-based compensation	0.9	0.9	0.6
Non-deductible officers compensation	1.3	1.1	0.7
Provision to return and deferred tax adjustments	0.3	(0.8)	(0.3)
Non-deductible promotional and entertainment expense	0.9	0.6	0.4
Fuel tax credit and other credits	(0.6)	(0.7)	(0.8)
Carryback claim, net of adjustments	0.0	(0.8)	(0.3)
Divestiture - Non-deductible goodwill	1.2	0.0	0.0
Rate changes	0.2	0.5	0.0
Valuation allowance	1.2	5.1	0.0
Other, net	(0.4)	0.2	0.0
Total income tax (benefit) expense	$ 30.1	$ 4.6	$ 5.6