Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Price Risk Management Activities (Textual)
Gain (loss) from components excluded from assessment of fair value hedge effectiveness, net	$ 0	$ 0	$ 0	$ 0
Gain (loss) from hedged firm commitment not qualifying as fair value hedge, net	28	0	28	0
Gain (loss) from components excluded from assessment of cash flow hedge effectiveness, net	0	0	0	0
Amount reclassifed from accumulated OCI into income on discontinuance of cash flow hedges	0	0	0	0
Accumulated other comprehensive income, cumulative after-tax gains on cash flow hedges	5		5
Gain (loss) from cash flow hedges to be reclassified within 12 months			9
Fair Value Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item	87	140	(180)	49
Gain (loss) recognized in income on hedged item	(91)	(147)	137	(61)
Loss recognized in income on derivatives (ineffective portion)	(4)	(7)	(43)	(12)
Cash Flow Hedging [Member] \| Commodity Contract [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in OCI on derivatives (effective portion)	(31)	0	16	0
Cash Flow Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) reclassified from accumulated OCI into income (effective portion)	(12)	0	36	0
Gain recognized in income on derivatives (ineffective portion)	31	0	26	0
Economic Hedging [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item	575	(67)	401	(380)
Economic Hedging [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item	574	(72)	423	(371)
Economic Hedging [Member] \| Foreign Currency Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item	1	5	(22)	(9)
Economic Hedging [Member] \| Future [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item				(542)
Trading Derivatives [Member] \| Commodity Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives or hedged item	$ 8	$ 8	$ 4	$ 14

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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