Risk Management - Effect on Income Statement Not Designated (Details) - Energy commodity derivative contracts - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	$ 99	$ 12	$ 371	$ 35
Revenues-Commodity sales
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	87	12	353	36
Cost of sales
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	12	0	18	(3)
Earnings from equity investments
Derivative [Line Items]
Gain/(loss) recognized in income on derivatives	0	0	0	2
Derivatives not designated as hedging instruments
Derivative [Line Items]
Gain/(loss) on settlement of derivative contracts	$ 96	$ (4)	$ 349	$ (2)

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

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