Summary of Significant Accounting Policies - Property (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 2.9	$ 3.1	$ 3.1
Property, Plant and Equipment, Net
Property, at cost	22.6	21.1
Accumulated depreciation	(12.4)	(9.4)
Property, net	10.2	11.7
Europe
Property, Plant and Equipment [Line Items]
Long-lived assets	6.6	6.3
Land and land improvements
Property, Plant and Equipment, Net
Property, at cost	0.8	0.7
Building and building improvements
Property, Plant and Equipment, Net
Property, at cost	$ 5.4	5.7
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	$ 14.2	12.2
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	13 years
Computer software, intangible asset
Property, Plant and Equipment, Net
Property, at cost	$ 1.9	1.8
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	$ 0.3	$ 0.7