Derivatives - Schedule of Fair Value of Outstanding Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 1.2	$ 9.5
Derivative Liabilities	14.2	2.3
Commodity swaps | Designated as Hedge | Other receivables
Derivatives, Fair Value [Line Items]
Derivative Assets	0.7	0.0
Commodity swaps | Designated as Hedge | Deferred charges and other
Derivatives, Fair Value [Line Items]
Derivative Assets	0.1	0.0
Commodity swaps | Designated as Hedge | Accounts payable
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0.0	0.2
Foreign exchange contracts | Designated as Hedge | Other receivables
Derivatives, Fair Value [Line Items]
Derivative Assets	0.0	7.8
Foreign exchange contracts | Designated as Hedge | Deferred charges and other
Derivatives, Fair Value [Line Items]
Derivative Assets	0.0	0.5
Foreign exchange contracts | Designated as Hedge | Accounts payable
Derivatives, Fair Value [Line Items]
Derivative Liabilities	3.8	0.2
Foreign exchange contracts | Designated as Hedge | Other long term liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	0.3	0.0
Foreign exchange contracts | Not Designated as Hedge | Other receivables
Derivatives, Fair Value [Line Items]
Derivative Assets	0.4	1.2
Foreign exchange contracts | Not Designated as Hedge | Accounts payable
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 10.1	$ 1.9