Restructuring (Schedule of Restructuring Reserve by Type of Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Charge to Income	$ 0.0	$ (2.5)	$ 4.9
Severance and termination related costs
Restructuring Reserve [Roll Forward]
Beginning balance	0.0	2.8
Charge to Income		0.0
Cash		(2.8)
Non-Cash		0.0
Ending balance		0.0	2.8
2013 restructuring
Restructuring Reserve [Roll Forward]
Beginning balance	0.0	1.5
Charge to Income	0.0	0.0	2.5
Cash		(1.5)
Non-Cash		0.0
Ending balance		0.0	1.5
2013 restructuring | Severance and termination related costs
Restructuring Reserve [Roll Forward]
Beginning balance	0.0	1.2
Charge to Income		0.0
Cash		(1.2)
Non-Cash		0.0
Ending balance		0.0	1.2
2013 restructuring | Other exit costs
Restructuring Reserve [Roll Forward]
Beginning balance	$ 0.0	0.3
Charge to Income		0.0
Cash		(0.3)
Non-Cash		0.0
Ending balance		$ 0.0	$ 0.3