Long-term and Short-term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Long-term debt
Unamortized discount, capitalized lease obligations and other	$ (34.9)	$ (34.1)
Long-Term Debt and Lease Obligation, Including Current Maturities	2,871.5	3,476.9
Less: Current portion	(8.6)	(609.1)
Total debt	$ 2,862.9	2,867.8
0.35% notes, payable in August 2023
Long-term debt
Stated interest rate	0.00003%
Debt instruments	$ 0.0	600.0
2.875% notes, payable in March 2025
Long-term debt
Stated interest rate	0.02875%
Debt instruments	$ 306.4	311.0
6.70% debentures, payable in January 2028
Long-term debt
Stated interest rate	0.00067%
Debt instruments	$ 250.0	250.0
3.50% notes, payable in March 2029
Long-term debt
Stated interest rate	0.035%
Debt instruments	$ 425.0	425.0
1.75% notes, payable in August 2031
Long-term debt
Stated interest rate	0.00018%
Debt instruments	$ 450.0	450.0
6.25% debentures, payable in December 2037
Long-term debt
Stated interest rate	0.00063%
Debt instruments	$ 250.0	250.0
4.20% notes, payable in March 2049
Long-term debt
Stated interest rate	0.042%
Debt instruments	$ 575.0	575.0
2.80% notes, payable in August 2061
Long-term debt
Stated interest rate	0.028%
Debt instruments	$ 450.0	450.0
5.20% debentures, payable in January 2098
Long-term debt
Stated interest rate	0.052%
Debt instruments	$ 200.0	$ 200.0