Income Taxes - U.S. and International Components of Income from Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Operating Loss Carryforwards [Line Items]
U.S.	$ 135.1	$ 50.0	$ 37.3
Income from operations, before tax	323.0	277.2	154.1
Australia
Operating Loss Carryforwards [Line Items]
Non-U.S.	7.4	8.7	7.8
Brazil
Operating Loss Carryforwards [Line Items]
Non-U.S.	35.3	25.3	13.7
Germany
Operating Loss Carryforwards [Line Items]
Non-U.S.	13.3	27.8	17.2
Singapore
Operating Loss Carryforwards [Line Items]
Non-U.S.	38.1	19.4	16.0
Switzerland
Operating Loss Carryforwards [Line Items]
Non-U.S.	22.5	0.0	0.0
United Kingdom
Operating Loss Carryforwards [Line Items]
Non-U.S.	77.7	104.8	41.4
Other international
Operating Loss Carryforwards [Line Items]
Non-U.S.	$ (6.4)	$ 41.2	$ 20.7