Leases - Summary of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 26.1	$ 27.7
Operating cash flows from finance leases	4.6	3.2
Financing cash flows from finance leases	48.4	36.3	$ 27.6
Non-cash items:
Right-of-use Assets Obtained In Exchange For New Operating Liabilities	17.7	27.1
Right-of-use Assets Obtained In Exchange For New Finance Liabilities	$ 68.3	$ 65.4