Derivative Financial Instruments and Hedging Gain (Loss) recognized in earnings from derivative instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Commodity contracts | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Loss (Gain) Recognized in Statement of Operations	$ 4.0	$ (0.4)	$ 7.5
Energy contracts | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Loss (Gain) Recognized in Statement of Operations	(6.4)	(1.3)	1.2
Foreign exchange contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
Loss (Gain) Recognized in Statement of Operations	1.5	0.8	0.0
Currency Swap | (Income) expense on swaps, net
Derivative Instruments, Gain (Loss) [Line Items]
Loss (Gain) Recognized in Statement of Operations	0.0	10.3	0.0
Interest rate swaps | (Income) expense on swaps, net
Derivative Instruments, Gain (Loss) [Line Items]
Loss (Gain) Recognized in Statement of Operations	$ (95.6)	$ (102.1)	$ 182.9