Risk Management - Not Designated as Hedges Effect on Income Statements (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	$ 29	$ (7)	$ 4
Energy commodity derivative contracts
Derivative [Line Items]
Loss on Derivative Instruments, Pretax	8	4
Derivative, Gain on Derivative			57
Commodity Sales \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	33	(9)	4
Cost of Sales \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	(7)	2	0
Earnings from Equity Investments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	$ 3	$ 0	$ 0

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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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
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Aggregate loss on all derivative instruments charged against earnings during the period, before tax effects.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
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-Section 50
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