Debt (Registered Public Offerings) (Details) € in Millions, $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2025 EUR (€)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 EUR (€)	Feb. 28, 2025 USD ($)	Feb. 28, 2025 EUR (€)
Debt Instrument [Line Items]
Repayment of debt		$ 380.1	$ 76.7
Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount					$ 1,040.0	€ 1,000
Debt issuance costs		12.0			$ 8.0
Euro-denominated Senior Notes | Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		$ 570.0		€ 500
Repayment of debt | €	€ 300
Interest rate		1.00%		1.00%
U.S. Dollar-denominated Senior Notes | Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount		$ 1,100.0