v2.4.0.6
Derivative Instruments (Details 2) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Derivatives, Fair Value [Line Items]    
Current derivative assets $ 1,051 $ 725
Long-term derivative assets 113 170
Total derivative assets 1,164 895
Current derivative liabilities 1,144 718
Long-term derivative liabilities 279 370
Total derivative liabilities 1,423 1,088
Net derivative assets (liabilities) (259) (193)
Fair Value of Derivative Assets 1,164 895
Fair Value of Derivative Liabilities 1,423 1,088
Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 61 163
Fair Value of Derivative Liabilities 167 195
Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 1,103 732
Fair Value of Derivative Liabilities 1,256 893
Interest Rate Swap [Member]
   
Derivatives, Fair Value [Line Items]    
Current derivative assets 0 0
Long-term derivative assets 10 4
Total derivative assets 10 4
Current derivative liabilities 166 197
Long-term derivative liabilities 154 174
Total derivative liabilities 320 371
Net derivative assets (liabilities) (310) (367)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 10 2
Fair Value of Derivative Liabilities 149 143
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 0 2
Fair Value of Derivative Liabilities 171 228
Commodity Option [Member]
   
Derivatives, Fair Value [Line Items]    
Current derivative assets 1,051 725
Long-term derivative assets 103 166
Total derivative assets 1,154 891
Current derivative liabilities 978 521
Long-term derivative liabilities 125 196
Total derivative liabilities 1,103 717
Net derivative assets (liabilities) 51 174
Commodity Option [Member] | Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 51 161
Fair Value of Derivative Liabilities 18 52
Commodity Option [Member] | Not Designated as Hedging Instrument [Member]
   
Derivatives, Fair Value [Line Items]    
Fair Value of Derivative Assets 1,103 730
Fair Value of Derivative Liabilities $ 1,085 $ 665