Risk Management - Effect on Income Statement Locations (Details) - Derivatives in cash flow hedging relationships - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Derivative [Line Items]
Cash flow hedge loss to be reclassified within twelve months	$ 257
Derivatives designated as hedging instruments
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	289	$ (279)
Gain/(loss) reclassified from Accumulated OCI into income	(48)	(17)
Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	379	(245)
Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(8)	0
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) recognized in OCI on derivative	(82)	(34)
Revenues-Commodity sales \| Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(8)	13
Cost of sales \| Derivatives designated as hedging instruments \| Interest rate contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	(17)	1
Other, net \| Derivatives designated as hedging instruments \| Foreign currency contracts
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	$ (23)	$ (31)

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Amount, before tax, of adjustments from accumulated other comprehensive income (AOCI) for gain (loss) from increase (decrease) in value of excluded component of derivative designated and qualifying as hedge. Adjustments include, but are not limited to, reclassifications for sale and settlement, and amounts recognized under systematic and rational method.

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