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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 74.8	$ 154.7	$ 80.3	$ 198.5
Customer Supply Agreement [Member] \| Revenue from Contract with Customer [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	57.5	155.5	74.6	197.4
Provisional Pricing Arrangements [Member] \| Revenue from Contract with Customer [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	$ 17.3	$ (0.8)	$ 5.7	$ 1.1

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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No definition available.

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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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

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