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Retirement Plans (Fair Value Asset Allocation) (Details) - USD ($) $ in Millions | Sep. 30, 2020 | Sep. 30, 2019
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | $ 360.4 | $ 351.6
Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 10.7 | 14.3
Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 349.7 | 337.3
Equity Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 76.8 | 66.4
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 7.4 | 6.9
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 69.4 | 59.5
Large Cap Growth Funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets |  | 29.8
Large Cap Growth Funds [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets |  | 0.0
Large Cap Growth Funds [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets |  | 29.8
Mid- Cap Growth Funds [Member] [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 13.5 | 9.8
Mid- Cap Growth Funds [Member] [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Mid- Cap Growth Funds [Member] [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 13.5 | 9.8
Large Cap Index Funds [Member] [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 32.8 |
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 |
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 32.8 |
Small Cap Growth Funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 12.7 | 9.6
Small Cap Growth Funds [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Small Cap Growth Funds [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 12.7 | 9.6
Mutual Fund [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 7.4 | 6.9
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 7.4 | 6.9
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
International Stocks [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 10.4 | 10.3
International Stocks [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
International Stocks [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 10.4 | 10.3
Fixed Income Funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 280.3 | 277.8
Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 280.3 | 277.8
Cash and Cash Equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 3.3 | 7.4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 3.3 | 7.4
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | $ 0.0 | $ 0.0

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