Financial Instruments and Risk Management (Narrative) (Details) $ in Millions		3 Months Ended
		Dec. 31, 2021 USD ($) contracts	Dec. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)
Derivative [Line Items]
Long-term debt		$ 1,448.0		$ 1,250.0
Fixed rate
Derivative [Line Items]
Long-term debt		1,250.0		1,250.0
Fair value of long-term debt		$ 1,305.6		1,300.1
Not designated as hedge | FX contract
Derivative [Line Items]
Open foreign currency contracts | contracts		5
Derivative, notional amount		$ 42.0
Cash flow hedge | Designated as hedge | FX contract
Derivative [Line Items]
Estimated fair value of derivative		$ 3.8		$ 3.3
Open foreign currency contracts | contracts		64
Derivative, notional amount		$ 121.0
Other expense (income), net | Not designated as hedge | FX contract
Derivative [Line Items]
Gain (loss) recognized in income	[1]	$ 1.1	$ (1.1)

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