Income Taxes (Reconciliation of Statutory Taxes to Effective Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Tax at U.S. federal statutory income tax rate of 35%	$ 19.8	$ 17.2	$ 23.4
Adjustments to reconcile to income tax expense (benefit):
Federal Valuation Allowance	0.1	1.3	0.5
State income taxes, net of federal benefit	3.3	3.2	4.8
Domestic production activities deduction	0.0	0.0	(2.4)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	0.0	0.0	(42.5)
Federal transition tax	0.0	(0.6)	7.5
Uncertain tax positions	1.0	(1.4)	0.0
Basis difference in foreign investment	0.1	(1.1)	0.0
Excess tax benefits related to stock compensation	(0.5)	(0.3)	(0.6)
Tax Credits	(1.8)	(1.8)	(1.7)
Other nondeductible expenses	0.4	1.3	0.5
Foreign income taxes	0.0	0.1	0.0
Nondeductible compensation	0.6	0.3	0.2
Other income tax	(0.9)	0.1	0.4
Income tax expense (benefit)	$ 22.1	$ 18.3	$ (9.9)