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Risk Management - Effect on Income Statement Locations (Details) - Derivatives in cash flow hedging relationships - 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) reclassified from Accumulated OCI into income				$ 12
Cash flow hedge gain (loss) to be reclassified within twelve months			$ 68
Derivatives designated as hedging instruments
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	$ (73)	$ 26	(21)	(171)
Gain/(loss) reclassified from Accumulated OCI into income	6	(53)	(94)	(46)
Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(143)	96	(29)	(74)
Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	0	(1)	(9)	(2)
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	70	(69)	17	(95)
Revenues-Commodity sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(47)	9	(145)	15
Cost of sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(7)	(3)	(12)	8
Earnings from equity investments \| Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(1)	0	(1)	2
Other, net \| Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	$ 61	$ (59)	$ 64	$ (71)