Leases - Supplemental Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 110.2	$ 101.7	$ 102.9
Operating cash flows from finance leases	0.2	0.3	0.6
Financing cash flows from finance leases	10.0	5.5	8.8
Right-of-use assets obtained in exchange for lease obligations
Operating leases	163.2	93.3	63.4
Financing leases	$ 9.3	$ 0.0	$ 11.8