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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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months			$ (181)
Derivatives designated as hedging instruments
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	$ (172)	$ (73)	(579)	$ (21)
Gain/(loss) reclassified from Accumulated OCI into income	(120)	6	(236)	(94)
Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(140)	(143)	(514)	(29)
Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	1	0	3	(9)
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(33)	70	(68)	17
Revenues—Commodity sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(94)	(47)	(167)	(145)
Cost of sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	8	(7)	10	(12)
Earnings from Equity Investments \| Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	0	(1)	0	(1)
Other, net \| Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	$ (34)	$ 61	(79)	$ 64
Write-Down Of Hedged Inventory \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income			$ 6