Financial Instruments and Risk Management - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	$ 25.7	$ (26.8)
Net Liabilities at estimated fair value	(4.2)	(34.8)
Foreign currency contracts | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Foreign Currency contracts	0.3	(0.2)
Foreign currency contracts | Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Foreign Currency contracts	(4.2)	(4.9)
Foreign currency contracts | Level 2 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Foreign Currency contracts	0.3	(0.2)
Derivatives - Interest Rate Swap contracts | Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Foreign Currency contracts	16.9	(7.3)
Commodity contract | Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Foreign Currency contracts	8.5	4.4
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Fair Value Amount	$ 2,206.0	$ 2,858.3