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Retirement Plans (Fair Value Asset Allocation) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 353.5	$ 360.4
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	283.2	10.7
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70.3	349.7
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104.6	76.8
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104.6	7.4
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	69.4
Large Cap Growth Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		32.8
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		32.8
Mid- Cap Growth Funds [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		13.5
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
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
Large Cap Index Funds [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52.1
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52.1
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0
Small Cap Growth Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		12.7
Small Cap Growth Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		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
Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		7.4
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		7.4
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
International Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52.5	10.4
International Stocks [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52.5	0.0
International Stocks [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	10.4
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	247.0	280.3
Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	176.7	0.0
Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70.3	280.3
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.9	3.3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.9	3.3
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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+ References

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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