Financial Instruments (Carrying Amount and Cumulative Hedging Adjustment) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative hedging adjustment, included in carrying amount	$ 23.4	$ 36.6
Current portion of long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying amounts of hedged item	549.7	0.0
Cumulative hedging adjustment, included in carrying amount	(0.3)	0.0
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying amounts of hedged item	1,522.5	2,057.1
Cumulative hedging adjustment, included in carrying amount	$ (23.1)	$ (36.6)