Intangible Assets - Gross and Net Intangible Assets by Major Class (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived License Agreements	$ 2.7	$ 0.0
Finite-Lived Intangible Assets, Accumulated Amortization	(14.0)	(12.7)
Finite-Lived Intangible Assets, Net	10.1	11.4
Finite-Lived Intangible Assets, Gross	24.1	24.1
Gross Finite and Indefinite-Lived Intangible Assets	26.8	24.1
Finite and Indefinited-Lived Accumulated Amortization and Impairment Charges	(14.0)	(12.7)
Intangible Assets, Net (Excluding Goodwill)	12.8	11.4
Computer Software, Intangible Asset [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Computer Software, Gross	2.7	2.7
Finite-Lived Intangible Assets, Accumulated Amortization	2.6	2.6
Finite-Lived Intangible Assets, Net	0.1	0.1
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Customer Lists, Gross	21.4	21.4
Finite-Lived Intangible Assets, Accumulated Amortization	11.4	10.1
Finite-Lived Intangible Assets, Net	$ 10.0	$ 11.3