Income Taxes - Schedule of Tax Attributes and Valuation Allowances (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Tax Benefit Amount
Capital loss carryforwards	$ 13.0	$ 15.3
Net operating loss carryforwards	85.2	130.4
State tax credit carryforward	19.3	$ 20.3
Subtotal	117.5
Other deferred tax assets	3.9
Total	121.4
Valuation Allowance
Tax credit carryforward	3.9
Subtotal	19.2
Total	23.1
Non-United States
Tax Benefit Amount
Net operating loss carryforward, subject to expiration	3.7
Net operating loss carryforward, not subject to expiration	42.2
Capital loss carryforwards	12.9
Valuation Allowance
Net operating loss carryforward, subject to expiration	3.7
Net operating loss carryforward, not subject to expiration	1.6
Non-United States capital loss carryforward	12.8
United States
Tax Benefit Amount
Net operating loss carryforward, subject to expiration	0.1
Net operating loss carryforward, not subject to expiration	26.5
Capital loss carryforwards	0.1
State tax credit carryforward	9.3
Valuation Allowance
Net operating loss carryforward, subject to expiration	0.0
Net operating loss carryforward, not subject to expiration	0.0
Non-United States capital loss carryforward	0.0
Tax credit carryforward	0.0
State and Local
Tax Benefit Amount
Net operating loss carryforwards	12.7
State tax credit carryforward	10.0
Valuation Allowance
Net operating loss carryforward, subject to expiration	1.1
Tax credit carryforward	$ 0.0