Long-term and Short-term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Long-term debt
Unamortized discount, capitalized lease obligations and other	$ (51.0)	$ (45.4)
Long-term debt	3,464.6	1,974.7
0.35% notes, payable in August 2023
Long-term debt
Debt instruments	$ 600.0	0.0
Stated interest rate	0.00003%
2.875% notes, payable in March 2025
Long-term debt
Debt instruments	$ 315.6	320.1
Stated interest rate	0.02875%
6.70% debentures, payable in January 2028
Long-term debt
Debt instruments	$ 250.0	250.0
Stated interest rate	0.00067%
3.50% notes, payable in March 2029
Long-term debt
Debt instruments	$ 425.0	425.0
Stated interest rate	0.035%
1.75% notes, payable in August 2031
Long-term debt
Debt instruments	$ 450.0	0.0
Stated interest rate	0.00018%
6.25% debentures, payable in December 2037
Long-term debt
Debt instruments	$ 250.0	250.0
Stated interest rate	0.00063%
4.20% notes, payable in March 2049
Long-term debt
Debt instruments	$ 575.0	575.0
Stated interest rate	0.042%
2.80% notes, payable in August 2061
Long-term debt
Debt instruments	$ 450.0	0.0
Stated interest rate	0.028%
5.20% debentures, payable in January 2098
Long-term debt
Debt instruments	$ 200.0	$ 200.0
Stated interest rate	0.052%

Debt Instrument, Unamortized Discount (Premium), Finance Lease Liability, Noncurrent, and Other

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
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-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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-Name Accounting Standards Codification
-Topic 210
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-Section S99
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-Subparagraph (SX 210.9-03(16))
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

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- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

+ 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
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- References

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