Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables
Commodity derivative and foreign currency contract receivables	$ 229	$ 102
Other receivables	166	69
Total receivables	7,379	6,955
Allowance for doubtful accounts	(34)	(33)
Receivables, net	7,345	6,922
Receivables from Contracts with Customers [Member]
Receivables
Receivables	4,673	5,686
Receivables from Certain Purchase and Sale Arrangements [Member]
Receivables
Receivables	$ 2,311	$ 1,098

Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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- References

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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- Definition

Carrying amount as of the balance sheet date of the asset arising from commodity contracts such as futures contracts tied to the movement of a particular commodity, which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer.

+ References

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- Definition

Amount, before allowance, of receivables classified as other, due within one year or the operating cycle, if longer.

+ References

No definition available.

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- Definition

The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowances established for the purpose of reducing such receivables to an amount that approximates their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Receivables Gross.

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