Risk Management - CF Hedging Effect on the Income Statements (Details) - Designated as Hedging Instrument - Cash Flow Hedging - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in OCI on derivative	$ (229)	$ 145	$ 227
Gain/(loss) reclassified from Accumulated OCI into income	(8)	(109)	268
Loss to be reclassified within twelve months	22
Energy commodity derivative contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in OCI on derivative	(168)	201	37
Energy commodity derivative contracts | Commodity Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	16	(59)	73
Energy commodity derivative contracts | Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	5	21	14
Energy commodity derivative contracts | Write-Down Of Hedged Inventory
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	12	21
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in OCI on derivative	(1)	3	0
Interest rate contracts | Earnings from Equity Investments
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	2	(4)	(5)
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net		(3)
Foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in OCI on derivative	(60)	(59)	190
Foreign currency contracts | Other, Net
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from Accumulated OCI into income	$ (31)	$ (67)	$ 186