Retirement Plans Retirement Plans - Defined Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 0.1	$ 0.2	$ 0.3
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.00%
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	$ 2.0
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	2.0
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	2.0
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	9.5
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.1	1.0
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	2.1
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	$ 2.1
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	20.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	80.00%
Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 0.1
Defined Benefit Plan, Benefit Obligation	1.7	1.6
Defined Benefit Plan, Funded (Unfunded) Status of Plan	1.6
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	38.9	35.6
Defined Benefit Plan, Benefit Obligation	$ 36.5	$ 32.5
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.10%	4.20%
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ (2.4)	$ (3.1)