v2.4.0.6
Derivative Instruments (Details 2) (Details) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Derivatives, Fair Value [Line Items]    
Derivative Assets, Current $ 487 $ 1,051
Derivative Assets, Noncurrent 146 113
Total derivative assets 633 1,164
Current derivative liabilities 457 1,144
Derivative Liabilities, Noncurrent 286 279
Total derivative liabilities 743 1,423
Net derivative assets (liabilities) (110) (259)
Fair Value of Derivative Assets 633 1,164
Fair Value of Derivative Liabilities 743 1,423
Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 22 [1] 61 [1]
Fair Value of Derivative Liabilities 191 [1] 167 [1]
Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 611 1,103
Fair Value of Derivative Liabilities 552 1,256
Interest Rate Swap [Member]
   
Derivatives, Fair Value [Line Items]    
Current derivative assets 0 0
Long-term derivative assets 5 10
Total derivative assets 5 10
Current derivative liabilities 36 166
Derivative Liabilities, Noncurrent 172 154
Total derivative liabilities 208 320
Net derivative assets (liabilities) (203) (310)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 5 [1] 10 [1]
Fair Value of Derivative Liabilities 189 [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 19 171
Commodity Option [Member]
   
Derivatives, Fair Value [Line Items]    
Current derivative assets 487 1,051
Long-term derivative assets 141 103
Total derivative assets 628 1,154
Current derivative liabilities 421 978
Derivative Liabilities, Noncurrent 114 125
Total derivative liabilities 535 1,103
Net derivative assets (liabilities) 93 51
Commodity Option [Member] | Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 17 [1] 51 [1]
Fair Value of Derivative Liabilities 2 [1] 18 [1]
Commodity Option [Member] | Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 611 1,103
Fair Value of Derivative Liabilities $ 533 $ 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.