Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements (Details) - Interest Rate Swap - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2022	Sep. 30, 2021
Other current assets
Derivative financial instruments
Fair values of the interest rate swap agreements	$ 0.7
Other non-current assets
Derivative financial instruments
Fair values of the interest rate swap agreements	23.9	$ 1.2
Other current liabilities
Derivative financial instruments
Fair values of the interest rate swap agreements	1.5	5.0
Other long-term liabilities
Derivative financial instruments
Fair values of the interest rate swap agreements		$ 1.8
Designated as Hedging Instrument \| Cash Flow Hedging
Derivative financial instruments
Losses recognized in income	$ 0.0

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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- Definition

Amount of gain (loss) from excluded component of derivative hedge, recognized in earnings. Excludes recognition under systematic and rational method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 20
-Section 45
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121577181&loc=SL110061172-113977

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959

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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.

+ References

No definition available.

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