Derivative and Financial Instruments - Commodity Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative assets	$ 199	$ 268
Other assets [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative assets	52	44
Other accruals [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative liabilities	196	300
Other liabilities and deferred credits [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative liabilities	$ 41	$ 34

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Fair value as of the balance sheet date of all price risk derivative assets not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

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- Definition

Fair value as of the balance sheet date of all price risk derivative liabilities not designated as hedging instruments.

+ References

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