Cost Reduction and Asset Actions (Carrying Amount of Accrual) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Cost reduction and asset actions	$ 0.0	$ 42.7	$ 0.0	$ 103.0	$ 151.4
Cost Reduction Actions
Restructuring Cost and Reserve [Line Items]
Cost reduction and asset actions		42.7			154.8
Noncash expenses					(84.2)
Cash expenditures			(25.0)		(36.9)
Amount reflected in pension liability			(0.4)		(2.0)
Amount reflected in other noncurrent liabilities					(2.2)
Currency translation adjustment					(0.3)
Accrued balance	16.1		16.1		41.5	$ 12.3
Cost Reduction Actions | Severance And Other Benefits
Restructuring Cost and Reserve [Line Items]
Cost reduction and asset actions		9.5		27.5	66.3
Noncash expenses					0.0
Cash expenditures			(24.8)		(35.7)
Amount reflected in pension liability			(0.4)		(2.0)
Amount reflected in other noncurrent liabilities					0.0
Currency translation adjustment					(0.3)
Accrued balance	15.4		15.4		40.6	12.3
Cost Reduction Actions | Asset Actions/Other
Restructuring Cost and Reserve [Line Items]
Cost reduction and asset actions		$ 33.2		$ 78.9	88.5
Noncash expenses					(84.2)
Cash expenditures			(0.2)		(1.2)
Amount reflected in pension liability			0.0		0.0
Amount reflected in other noncurrent liabilities					(2.2)
Currency translation adjustment					0.0
Accrued balance	$ 0.7		$ 0.7		$ 0.9	$ 0.0