Income Taxes - Additional Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Operating Loss Carryforwards [Line Items]
Decrease to the valuation allowance	$ 1.1
Undistributed losses of foreign subsidiaries	99.8
Undistributed earnings of foreign subsidiaries, estimated taxes recognized upon distribution	5.0
Amount of foreign uncertain tax positions to expire within twelve months	0.8
Income tax penalties and interest expense (benefit)	0.2	$ (0.8)	$ 0.3
Reversal of previously accrued interest and penalties	0.4
Accrued interest and penalties	0.7	$ 1.0	$ 1.8
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	25.9
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	52.7
Tax credit carryforward	$ 1.7