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, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
U.S. Federal statutory rate		$ 17.1	$ 20.3	$ (0.7)
U.S. Federal statutory rate percentage		21.00%	21.00%	21.00%
State and local income taxes, net of federal income tax effect	[1],[2]	$ 4.9	$ 6.2	$ 4.8
State and local income taxes, net of federal income tax effect percentage	[1],[2]	6.00%	6.40%	(155.50%)
Tax credits		$ (0.6)	$ (0.6)	$ (0.7)
Tax credits percentage		(0.70%)	(0.60%)	22.40%
Foreign tax effects		$ 0.9	$ 0.0	$ 0.0
Foreign tax effects percentage		1.10%	0.00%	0.00%
Nontaxable or Nondeductible Items
Non-deductible officers compensation		$ 2.1	$ 1.3	$ 1.1
Non-deductible officers' compensation percentage		2.60%	1.40%	(36.40%)
Divestiture - Non-deductible goodwill		$ 0.0	$ 1.2	$ 0.0
Divestiture - Non-deductible goodwill percentage		0.00%	1.20%	0.00%
Other adjustments		$ 0.9	$ 1.7	$ 0.1
Other adjustments percentage		1.10%	1.80%	0.70%
Total income tax (benefit) expense		$ 25.3	$ 30.1	$ 4.6
Total income tax (benefit) expense percentage		31.10%	31.20%	(149.20%)

[1] Included in State and Local Income Taxes is the effect of a valuation allowance on state taxes related to net operating losses and 163(j) interest expense carryforward ($2.1, $1.2, and $5.1, in FY25, FY24, and FY23 respectively)

[2] State taxes in California, Colorado, Florida, Massachusetts, New York and Texas made up the majority (greater than 50%) of the tax effect in this category