Derivative Financial Instruments (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Derivatives, Fair Value
Derivative, notional amount	$ 350.0	$ 350.0
AOCI, cumulative net hedging (loss) gain, before tax	(7.1)	(9.4)
AOCI, cumulative net hedging (loss) gain, after tax	(6.7)	(8.8)
Unrealized derivative net loss (gain) to be reclassified during next 12 months, net	2.3
Derivative liability, current	4.7	4.6
Derivative liability, noncurrent	1.1	5.8
Derivative liability	5.8	10.4
Derivative loss (gain), net	2.5	2.8
Derivative cash settlements paid, net	(4.8)	(1.8)
Fair Value Adjustment
Derivatives, Fair Value
Derivative loss (gain), net	0.2	1.6
Reclassification from AOCI
Derivatives, Fair Value
Derivative loss (gain), net	$ 2.3	$ 1.2

Accumulated Other Comprehensive Income, Cumulative Changes in Net Income (Loss) from Hedges, Before Tax

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- Definition

Derivative Instruments Not Designated as Hedging Instruments, Cash Settlements, Net

+ References

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- Definition

Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
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- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

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-Name Accounting Standards Codification
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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Nominal or face amount used to calculate payment on derivative.

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- Definition

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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- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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