Intangible Assets - Gross and Net Intangible Assets by Major Class (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 10.7
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	(10.8)	(10.1)
Finite-Lived Intangible Assets, Net	$ 10.6	$ 11.3