Financial Instruments and Risk Management (Narrative) (Details) $ in Millions		3 Months Ended
		Dec. 31, 2019 USD ($) contracts	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)
Derivative [Line Items]
Long-term debt		$ 1,100.0		$ 1,217.0
Fixed rate
Derivative [Line Items]
Long-term debt		1,100.0
Fair value of long-term debt		$ 1,095.6		1,071.2
Not designated as hedge | FX contract
Derivative [Line Items]
Open foreign currency contracts | contracts		5
Derivative, notional amount		$ 39.0
Cash flow hedge | Designated as hedge | FX contract
Derivative [Line Items]
Estimated fair value of derivative		$ (0.1)		$ 1.7
Open foreign currency contracts | contracts		61
Derivative, notional amount		$ 125.0
Other (income) expense, net | Not designated as hedge | FX contract
Derivative [Line Items]
Gain (loss) recognized in income	[1]	$ 0.3	$ (1.3)

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