Borrowing Arrangements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Long-Term Debt, Maturity, Year One	$ 1.1
Long-Term Debt, Maturity, Year Two	0.9
Long-Term Debt, Maturity, Year Three	0.5
Long-Term Debt, Maturity, Year Four	0.1
Long-Term Debt, Maturity, Year Five	$ 0.0
Line of Credit Facility, Expiration Date	Jul. 29, 2025
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 175.0
Potential Increase In The Size Of Credit Facility	$ 150.0
Line of Credit Facility, Interest Rate at Period End	200.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	37.50%
Maximum excess availability level at which financial maintenance covenants would apply	$ 17.5
Maximum excess availability level at which financial maintenance covenants would apply, as a percentage of aggregate commitments	10.00%
Outstanding Letter Of Credit Accrued Fees And Expenses	$ 14.1
Line of Credit Facility, Remaining Borrowing Capacity	133.9
Outstanding Letter Of Credit Accrued Fees And Expenses	14.1
Line of Credit Facility, Remaining Borrowing Capacity	133.9
Potential Increase In The Size Of Credit Facility	$ 150.0
Line of Credit Facility, Maximum Borrowing Capacity		$ 175.0
Line of Credit Facility, Interest Rate at Period End	200.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	37.50%
Maximum excess availability level at which financial maintenance covenants would apply	$ 17.5
Maximum excess availability level at which financial maintenance covenants would apply, as a percentage of aggregate commitments	10.00%
Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage		5.50%
Financial Liabilities Fair Value Disclosure	$ 465.8
Financial Liabilities Fair Value Disclosure	465.8
Debt Instrument, Interest Rate, Effective Percentage		5.50%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs		$ 6.6
Payments of Debt Issuance Costs		$ 6.6
Swing Line Loans [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	25.0
Line of Credit Facility, Maximum Borrowing Capacity	25.0
Letter Of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	60.0
Line of Credit Facility, Maximum Borrowing Capacity	$ 60.0
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		250.00%
Long-term Debt, Gross		$ 500.0
Long-term Debt, Gross		$ 500.0
Debt Instrument, Basis Spread on Variable Rate		250.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	200.00%
Debt Instrument, Basis Spread on Variable Rate	200.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.75%
Debt Instrument, Interest Rate, Stated Percentage		0.75%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	225.00%
Debt Instrument, Basis Spread on Variable Rate	225.00%
Base Rate [Member] \| Minimum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	100.00%
Debt Instrument, Basis Spread on Variable Rate	100.00%
Base Rate [Member] \| Maximum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	125.00%
Debt Instrument, Basis Spread on Variable Rate	125.00%

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Maximum excess availability level at which financial maintenance covenants would apply, as a percentage of aggregate commitments.

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Total other amounts reducing excess availability.

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Potential increase in the size of credit facility.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

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The effective interest rate at the end of the reporting period.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

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