Short-Term and Long-Term Debt - Narrative (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Mar. 31, 2025	Sep. 30, 2024	Apr. 01, 2025	Dec. 31, 2022
Debt Instrument [Line Items]
Short-term debt	$ 1,110.0	$ 771.0
Commercial Paper
Debt Instrument [Line Items]
Short-term debt	$ 996.0	$ 657.0
Debt, weighted average interest rate	4.57%	5.14%
Debt instrument, term	31 days	24 days
Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 75.0
Short-term bank loans and notes payable	$ 70.0	$ 70.0
Stated interest rate	5.32%	6.17%
Interest Bearing Loan
Debt Instrument [Line Items]
Short-term debt		$ 42.0
Long-term debt	$ 42.0
Interest Bearing Loan | Subsequent Event
Debt Instrument [Line Items]
Short-term debt			$ 14.0