Income Taxes - U.S. and International Components of Income (Loss) from Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Operating Loss Carryforwards [Line Items]
U.S.	$ 37.3	$ 88.8	$ (2.6)
Income from operations, before tax	154.1	206.7	111.0
Australia
Operating Loss Carryforwards [Line Items]
Non-U.S.	7.8	1.4	0.4
Brazil
Operating Loss Carryforwards [Line Items]
Non-U.S.	13.7	7.6	12.6
Germany
Operating Loss Carryforwards [Line Items]
Non-U.S.	17.2	10.4	(0.3)
Singapore
Operating Loss Carryforwards [Line Items]
Non-U.S.	16.0	20.5	22.6
United Kingdom
Operating Loss Carryforwards [Line Items]
Non-U.S.	41.4	58.5	71.5
Other international
Operating Loss Carryforwards [Line Items]
Non-U.S.	$ 20.7	$ 19.5	$ 6.8