v2.4.0.6

Derivative Instruments (Details 2) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Current derivative assets	$ 1,403		$ 1,051
Long-term derivative assets	186		113
Total derivative assets	1,589		1,164
Current derivative liabilities	1,301		1,144
Derivative Liabilities, Noncurrent	257		279
Total derivative liabilities	(1,558)		(1,423)
Net derivative assets (liabilities)	31		(259)
Fair Value of Derivative Assets	1,589		1,164
Fair Value of Derivative Liabilities	1,558		1,423
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	51	[1]	61	[1]
Fair Value of Derivative Liabilities	152	[1]	167	[1]
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	1,538		1,103
Fair Value of Derivative Liabilities	1,406		1,256
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	0		0
Long-term derivative assets	8		10
Total derivative assets	8		10
Current derivative liabilities	30		166
Derivative Liabilities, Noncurrent	139		154
Total derivative liabilities	(169)		(320)
Net derivative assets (liabilities)	(161)		(310)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	8	[1]	10	[1]
Fair Value of Derivative Liabilities	145	[1]	149	[1]
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	24		171
Commodity Option [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	1,403		1,051
Long-term derivative assets	178		103
Total derivative assets	1,581		1,154
Current derivative liabilities	1,271		978
Derivative Liabilities, Noncurrent	118		125
Total derivative liabilities	(1,389)		(1,103)
Net derivative assets (liabilities)	192		51
Commodity Option [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	43	[1]	51	[1]
Fair Value of Derivative Liabilities	7	[1]	18	[1]
Commodity Option [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value of Derivative Assets	1,538		1,103
Fair Value of Derivative Liabilities	$ 1,382		$ 1,085
[1] Includes accumulated fair value of derivative instruments as of the date hedge accounting was discontinued, net of amortized fair value for settlement periods which have transpired.

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Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative asset or group of derivative assets.

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