Long-term and Short-term Debt - Schedule of Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Carrying Value
Current portion of long-term debt	$ 0.0	$ 300.5
Long-term debt	1,974.7	1,956.4
Carrying Value
Carrying Value
Current portion of long-term debt	0.0	300.5
Long-term debt	1,974.7	1,956.4
Fair Value
Fair Value
Current portion of long-term debt	0.0	300.1
Long-term debt	$ 2,497.7	$ 2,380.8

Long-term Debt, Current Maturities, Fair Value

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- References

No definition available.

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- References

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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