Retirement Plans Retirement Plans - Defined Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 0.2		$ 0.2
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	9.7
Defined Benefit Plan, Plan Assets, Contributions by Employer	1.0	$ 2.0
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	2.1
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	$ 2.0
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	20.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	80.00%
Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0.1
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	1.6	1.7
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	35.6	36.3
Defined Benefit Plan, Benefit Obligation	$ 32.5	$ 34.7
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.20%	3.75%