Intangible Assets - Gross and Net Intangible Assets by Major Class (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 6.0
Finite-Lived Intangible Assets, Net	13.7
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Trade Names, Gross	1.1	$ 1.1
Finite-Lived Intangible Assets, Accumulated Amortization	(0.8)	(0.6)
Finite-Lived Intangible Assets, Net	0.3	0.5
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	(2.4)	(2.4)
Finite-Lived Intangible Assets, Net	0.3	0.3
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Customer Lists, Gross	20.0	14.0
Finite-Lived Intangible Assets, Accumulated Amortization	(6.9)	(5.7)
Finite-Lived Intangible Assets, Net	$ 13.1	$ 8.3