Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Price Risk Management Activities (Textual)
Gain (loss) from components excluded from assessment of fair value hedge effectiveness, net	$ 0	$ 0
Gain (loss) from hedged firm commitment not qualifying as fair value hedge, net	0	0
Gain (loss) from components excluded from assessment of cash flow hedge effectiveness, net	0	0
Amount reclassifed from accumulated OCI into income on discontinuance of cash flow hedges	0	0
Accumulated other comprehensive income, cumulative after-tax gains on cash flow hedges	19
Gain (loss) from cash flow hedges to be reclassified within 9 months	19
Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	228	86
Fair Value Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	(267)	(91)
Amount of gain or (loss) recognized in income for ineffective portion of derivative	(39)	(5)
Cash Flow Hedging [Member] \| Commodity Contract [Member]
Effect of Derivative Instruments on Income and OCI
Gain recognized in OCI on derivatives (effective portion)	47	0
Cash Flow Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain reclassified from accumulated OCI into income (effective portion)	48	0
Loss recognized in income on derivatives (ineffective portion)	(5)	0
Economic Hedging [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	(174)	(313)
Economic Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	(151)	(299)
Economic Hedging [Member] \| Foreign Currency Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	(23)	(14)
Economic Hedging [Member] \| Future [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives		(542)
Trading Derivatives [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Amount of gain or (loss) recognized in income on derivatives	$ (4)	$ 6

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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The net gain (loss) relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings.

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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

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