DERIVATIVE INSTRUMENTS (Schedule Of Derivatives Not Designated As Hedging Instruments) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 154.7	$ 30.8	$ 198.5	$ 63.0
Customer Supply Agreement [Member] \| Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	155.5	51.9	197.4	69.6
Provisional Pricing Arrangements [Member] \| Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	(0.8)	(21.1)	1.1	(5.3)
Commodity Contract [Member] \| Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 0.0	$ 0.0	$ 0.0	$ (1.3)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or 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 (e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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