Long-term and Short-term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Long-term debt
Unamortized discount, capitalized lease obligations and other	$ (45.4)	$ (50.1)
Total	1,974.7	2,256.9
Less current portion	0.0	(300.5)
Long-term debt	1,974.7	1,956.4
2.050% notes, repaid in March 2020
Long-term debt
Debt instruments	$ 0.0	299.4
Stated interest rate	2.05%
2.875% notes, payable in March 2025
Long-term debt
Debt instruments	$ 320.1	307.6
Stated interest rate	2.875%
6.70% debentures, payable in January 2028
Long-term debt
Debt instruments	$ 250.0	250.0
Stated interest rate	6.70%
3.500% notes, payable in March 2029
Long-term debt
Debt instruments	$ 425.0	425.0
Stated interest rate	3.50%
6.25% debentures, payable in December 2037
Long-term debt
Debt instruments	$ 250.0	250.0
Stated interest rate	6.25%
4.200% notes, payable in March 2049
Long-term debt
Debt instruments	$ 575.0	575.0
Stated interest rate	4.20%
5.20% debentures, payable in January 2098
Long-term debt
Debt instruments	$ 200.0	$ 200.0
Stated interest rate	5.20%

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

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Amount of unamortized debt discount (premium) and debt issuance costs.

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

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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.

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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.

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