Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Cost of Sales [Member] - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Economic Hedging [Member] \| Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ (139)	$ 64
Economic Hedging [Member] \| Foreign Currency Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	(3)	22
Trading Derivatives [Member] \| Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ 41	$ 20

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration