Financial Instruments and Risk Management (Narrative) (Details) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2018 USD ($) contracts	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) contracts	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)
Derivative [Line Items]
Long-term debt		$ 1,281.4		$ 1,281.4		$ 1,525.4
Fixed rate
Derivative [Line Items]
Long-term debt		1,096.5		1,096.5		1,095.7
Fair value of long-term debt		1,059.5		1,059.5		1,143.8
Loans payable
Derivative [Line Items]
Long-term debt	[1]	184.9		184.9		184.7
Fair value of long-term debt		$ 185.0		$ 185.0		185.0
Not designated as hedge | FX contract
Derivative [Line Items]
Open foreign currency contracts | contracts		4		4
Notional value		$ 48.0		$ 48.0
Cash flow hedge | Designated as hedge | FX contract
Derivative [Line Items]
Estimated fair value of derivative		$ 2.6		$ 2.6		$ (1.6)
Open foreign currency contracts | contracts		64		64
Notional value		$ 137.8		$ 137.8
Other expense (income), net | Not designated as hedge | FX contract
Derivative [Line Items]
Change in estimate fair value of foreign currency contracts	[2]	$ 3.0	$ 1.6	$ 0.2	$ 2.0

[1] At June 30, 2018, the balance for the senior notes due 2021, the senior notes due 2022 and the term loan are reflected net of debt issuance costs of $1.4, $1.6 and $0.1, respectively. At September 30, 2017, the balance for the senior notes due 2021, the senior notes due 2022 and the term loan are reflected net of debt issuance costs of $1.7, $1.9 and $0.3, respectively.

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