Financial Instruments and Risk Management (Narrative) (Details) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2020 USD ($) contracts		Jun. 30, 2019 USD ($)	[1]	Jun. 30, 2020 USD ($) contracts	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Derivative [Line Items]
Long-term debt	$ 1,250.0				$ 1,250.0		$ 1,217.0
Fixed rate
Derivative [Line Items]
Long-term debt	1,250.0				1,250.0
Fair value of long-term debt	$ 1,245.1				$ 1,245.1		1,071.2
Not designated as hedge | FX contract
Derivative [Line Items]
Open foreign currency contracts | contracts	5				5
Derivative, notional amount	$ 39.0				$ 39.0
Cash flow hedge | Designated as hedge | FX contract
Derivative [Line Items]
Estimated fair value of derivative	$ (0.4)				$ (0.4)		$ 1.7
Open foreign currency contracts | contracts	64				64
Derivative, notional amount	$ 131.7				$ 131.7
Other (income) expense, net | Not designated as hedge | FX contract
Derivative [Line Items]
Gain (loss) recognized in income	$ 0.3	[1]	$ (1.1)		$ (0.2)	$ (1.7)

[1] Gain (loss) was recorded in Other (income) expense, net.