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Derivatives - Net Gain (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ (77.0)	$ (9.4)	$ (238.4)	$ (1.9)
Commodity contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	(75.6)	(11.0)	(235.2)	0.8
Commodity contract [Member] | Glencore [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	(26.3)	(4.6)	(79.8)	0.1
Foreign exchange contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ (1.4)	$ 1.6	$ (3.2)	$ (2.7)

X

- Definition

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

+ References

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=125515794&loc=SL5618551-113959

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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