Debt - Issuance of Green Senior Notes (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 14,485.5	$ 10,292.5
Note 4.60% due 2029 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.60%
Long-term debt, principal amount	$ 750.0	0.0
Note 4.75% due 2031 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.75%
Long-term debt, principal amount	$ 600.0	0.0
Note 4.85% due 2034 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.85%
Long-term debt, principal amount	$ 1,150.0	$ 0.0
Green Bonds | Senior Notes
Debt Instrument [Line Items]
Long-term debt, principal amount	$ 2,500.0