Financial Instruments Narrative (Details) item in Millions, bbl in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2020 USD ($) item bbl	Dec. 31, 2019 USD ($) bbl	Dec. 31, 2018 USD ($)
Derivatives, Fair Value [Line Items]
Unrealized Gain On Derivative Contracts		$ 785	$ 182
Investment Segment
Derivatives, Fair Value [Line Items]
Fair value of derivative instruments with credit risk related contingent features in a liability position		1	266
Investment Segment | Not designated as hedging instrument | Other assets [Member]
Derivatives, Fair Value [Line Items]
Unrealized Gain On Derivative Contracts	[1]	785	182
Energy Segment | Not designated as hedging instrument | Other assets [Member]
Derivatives, Fair Value [Line Items]
Unrealized Gain On Derivative Contracts		17	8
Energy Segment | Not designated as hedging instrument | Cost of Goods and Service Benchmark [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income		$ 55	$ 19	$ 146
Commodity contracts not considered probable of settlement | Energy Segment | Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative volume (barrels) | bbl		6	4
Forward Contracts [Member] | Energy Segment | Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative, Number of Instruments Held | bbl		13
Credit Default Swap [Member] | Energy Segment | Not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative, Number of Instruments Held | item		7

[1] Excludes netting of cash collateral received and posted. The total collateral posted at December 31, 2020 and 2019 was $872 million and $903 million, respectively, across all counterparties, which are included in cash held at consolidated affiliated partnerships and restricted cash in the consolidated balance sheets.