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Risk Management - Effect on Income Statement Locations (Details) - Derivatives in cash flow hedging relationships - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income		$ 12
Cash flow hedge loss to be reclassified within twelve months			$ 116
Derivatives designated as hedging instruments
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	$ (246)	82	52	$ (197)
Gain/(loss) reclassified from Accumulated OCI into income	(61)	24	(100)	7
Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(273)	75	114	(170)
Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(1)	(1)	(9)	(1)
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	28	8	(53)	(26)
Revenues-Commodity sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(84)	(7)	(98)	6
Cost of sales \| Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(2)	10	(5)	11
Earnings from equity investments \| Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	0	2	0	2
Other, net \| Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	$ 25	$ 19	$ 3	$ (12)