Leases - Operating Lease Costs and Other Related Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Leases [Abstract]
Operating lease costs	$ 25.7	$ 25.5
Cash paid for amounts included in the measurement of operating lease liabilities	16.4	16.8
Right-of-use assets obtained in exchange for operating lease liabilities	$ 12.4	$ 36.2
Weighted average remaining lease term (years)	10 years 10 months 24 days	11 years 6 months
Weighted average discount rate	4.30%	4.00%