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, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Price Risk Management Activities (Textual)
Gain (loss) from hedged firm commitment not qualifying as fair value hedge, net	$ 0	$ 28	$ 0	$ 28
Accumulated other comprehensive income, cumulative after-tax losses on cash flow hedges	(2)		(2)
Gain (loss) from cash flow hedges to be reclassified within 12 months			(3)
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	(20)	87	(21)	(180)
Gain recognized in income on hedged item	22	(91)	22	137
Loss recognized in income on derivatives (ineffective portion)	2	(4)	1	(43)
Cash Flow Hedging [Member] \| Commodity Contract [Member]
Effect of Derivative Instruments on Income and OCI
Gain recognized in OCI on derivatives (effective portion)	(10)	(31)	(9)	16
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)	(8)	(12)	(5)	36
Loss recognized in income on derivatives (ineffective portion)	(2)	31	(3)	26
Economic Hedging [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	257	575	317	401
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	246	574	281	423
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	11	1	36	(22)
Trading Derivatives [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	(4)	8	(15)	4
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	3	8	5	4
Trading Derivatives [Member] \| RINs Fixed-Price Contracts [Member] \| Cost of Sales [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ (7)	$ 0	$ (20)	$ 0

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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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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

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Amount of net gain (loss) recognized in earnings when a hedged firm commitment no longer qualifies as a fair value hedge.

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