Leases - Summary of Supplemental Cash Flow Information (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	$ 27.7	$ 28.9
Operating cash flows from finance leases	3.2	1.6
Financing cash flows from finance leases	36.3	27.6	$ 27.0
Non-cash items:
Right-of-use Assets Obtained In Exchange For New Operating Liabilities	27.1	33.4
Right-of-use Assets Obtained In Exchange For New Finance Liabilities	$ 65.4	$ 26.3