Financial Instruments and Risk Management - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - Designated as Hedging Instrument - Cash Flow Hedging - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives - Foreign Currency contracts	$ 62.8		$ 62.8		$ 82.4
(Loss)/Gain Recognized in OCI	12.0	$ (7.5)	(8.5)	$ (13.2)
Loss Reclassified From OCI into Income(Effective Portion)	5.4	6.6	11.1	19.1
Foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives - Foreign Currency contracts	0.6		0.6		3.3
(Loss)/Gain Recognized in OCI	4.0	(0.2)
Loss Reclassified From OCI into Income(Effective Portion)	(0.3)	1.1
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives - Foreign Currency contracts	62.7		62.7		79.8
(Loss)/Gain Recognized in OCI	11.3	(6.7)	(1.3)	(6.7)
Loss Reclassified From OCI into Income(Effective Portion)	7.8	6.3	15.8	11.2
Zinc contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives - Foreign Currency contracts	(0.5)		(0.5)		$ (0.7)
(Loss)/Gain Recognized in OCI	(3.3)	(0.6)	(5.1)	2.9
Loss Reclassified From OCI into Income(Effective Portion)	$ (2.1)	$ (0.8)	(5.3)	0.3
Foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
(Loss)/Gain Recognized in OCI			(2.1)	(9.4)
Loss Reclassified From OCI into Income(Effective Portion)			$ 0.6	$ 7.6