Income Taxes (Reconciliation of Statutory Taxes to Effective Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Tax at U.S. federal statutory income tax rate of 35%	$ 53.4	$ 34.3	$ 22.9
Adjustments to reconcile to income tax expense (benefit):
State income taxes, net of federal benefit	9.0	9.6	1.5
Uncertain tax positions	0.2	(2.3)	0.5
Nondeductible compensation	4.0	2.1	1.8
Nondeductible expenses, other than compensation	0.7	0.6	0.9
Valuation allowances	0.3	3.0	(0.6)
Basis difference in foreign investment	0.0	0.1	0.1
Foreign income taxes	(1.6)	(0.8)	(2.0)
Excess tax (benefit) deficit related to stock compensation	(2.0)	(0.6)	0.3
Tax credits	(2.9)	(3.3)	(3.5)
Goodwill impairment	0.0	1.9	0.0
Other income tax	1.4	2.9	1.6
Income tax expense (benefit)	$ 62.5	$ 47.5	$ 23.5