Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 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	0	0	28	0
Gain (loss) from components excluded from assessment of cash flow hedge effectiveness, net	0	0	0	0
Accumulated other comprehensive income, cumulative after-tax losses on cash flow hedges	(6)		(6)
Gain (loss) from cash flow hedges to be reclassified within 12 months			(9)
Amount reclassifed from accumulated OCI into income on discontinuance of cash flow hedges	0	0	0	0
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	(127)	170	(307)	219
Gain (loss) recognized in income on hedged item	101	(161)	238	(222)
Gain (loss) recognized in income on derivatives (ineffective portion)	(26)	9	(69)	(3)
Cash Flow Hedging [Member] \| Commodity Contract [Member]
Effect of Derivative Instruments on Income and OCI
Gain recognized in OCI on derivatives (effective portion)	27	20	43	20
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)	45	0	81	0
Gain (loss) recognized in income on derivatives (ineffective portion)	(3)	4	23	4
Economic Hedging [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	(354)	79	47	(301)
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	(333)	9	90	(362)
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	(21)	41	(43)	32
Economic Hedging [Member] \| Other Contract [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	0	29	0	29
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	$ (13)	$ 3	$ (9)	$ 17

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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