Derivative Instruments and Hedging Activities - Effects of Derivative Instruments on the Condensed Consolidated Statements of Income and Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Derivatives Not Designated as Hedging Instruments
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	$ 18.4	$ 109.8
Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in AOCI	(0.6)	18.3
Gain (Loss) Reclassified from AOCI into Income	0.5	6.6
Commodity contracts \| Derivatives Not Designated as Hedging Instruments \| Cost of sales
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	24.4	108.5
Commodity contracts \| Derivatives Not Designated as Hedging Instruments \| Revenues
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	(1.3)	0.1
Commodity contracts \| Derivatives Not Designated as Hedging Instruments \| Operating and administrative expenses
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	0.1	(0.1)
Foreign currency contracts \| Derivatives Not Designated as Hedging Instruments \| (Losses) gains on foreign currency contracts, net
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	(4.8)	1.3
Foreign currency contracts \| Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in AOCI	(1.4)	17.2
Foreign currency contracts \| Cash Flow Hedges \| Cost of sales
Derivative Instruments, Gain (Loss)
Gain (Loss) Reclassified from AOCI into Income	0.8	7.9
Cross-currency contracts \| Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in AOCI	0.1	(0.1)
Cross-currency contracts \| Cash Flow Hedges \| Interest expense/other operating income, net
Derivative Instruments, Gain (Loss)
Gain (Loss) Reclassified from AOCI into Income	0.2	(0.3)
Interest rate contracts \| Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in AOCI	0.7	1.2
Interest rate contracts \| Cash Flow Hedges \| Interest expense
Derivative Instruments, Gain (Loss)
Gain (Loss) Reclassified from AOCI into Income	$ (0.5)	$ (1.0)

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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