Financial Instruments and Risk Management - Offsetting Assets and Liabilities (Details) - Foreign currency contracts - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	$ 0.7	$ 0.8
Gross amounts offset in the Balance Sheet	0.0	(0.4)
Net amounts of assets presented in the Balance Sheet	0.7	0.4
Gross amounts of recognized liabilities	(11.4)	(6.0)
Gross amounts offset in the Balance Sheet	0.0	(0.5)
Net amounts of liabilities presented in the Balance Sheet	$ (11.4)	$ (5.5)

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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