Summary of Significant Accounting Policies - Property (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Property, Plant and Equipment [Line Items]
Depreciation	$ 1.7	$ 1.6	$ 2.5
Property, Plant and Equipment, Net
Property, at cost	24.0	21.5
Accumulated depreciation	(15.5)	(13.5)
Property, net	8.5	8.0
Europe
Property, Plant and Equipment [Line Items]
Long-lived assets	7.1	6.0
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	7.1	6.0
Land and land improvements
Property, Plant and Equipment, Net
Property, at cost	0.7	0.7
Building and building improvements
Property, Plant and Equipment, Net
Property, at cost	$ 5.6	5.4
Building and building improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Building and building improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	33 years
Machinery and equipment
Property, Plant and Equipment, Net
Property, at cost	$ 14.1	12.6
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Computer software, intangible asset
Property, Plant and Equipment, Net
Property, at cost	$ 2.4	2.3
Computer software, intangible asset | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Computer software, intangible asset | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Construction in progress
Property, Plant and Equipment, Net
Property, at cost	$ 1.2	$ 0.5