v2.4.0.8
Derivative Instruments (Details 2) (Details) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2013
Dec. 31, 2012
Derivatives, Fair Value [Line Items]    
Derivative assets, current $ 471 $ 339
Derivative Assets, Noncurrent 148 98
Total derivative assets 619 437
Current derivative liabilities 472 357
Derivative Liabilities, Noncurrent 333 293
Total derivative liabilities 805 650
Net derivative assets (liabilities) (186) (213)
Designated as Hedging Instrument [Member]
    
Derivatives, Fair Value [Line Items]    
Total derivative assets 8 4
Total derivative liabilities 128 184
Not Designated as Hedging Instrument [Member]
    
Derivatives, Fair Value [Line Items]    
Total derivative assets 611 433
Total derivative liabilities 677 466
Interest Rate Swap [Member]
    
Derivatives, Fair Value [Line Items]    
Derivative assets, current 0 0
Derivative Assets, Noncurrent 8 4
Total derivative assets 8 4
Current derivative liabilities 48 40
Derivative Liabilities, Noncurrent 96 160
Total derivative liabilities 144 200
Net derivative assets (liabilities) (136) (196)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
    
Derivatives, Fair Value [Line Items]    
Total derivative assets 8 4
Total derivative liabilities 128 184
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
    
Derivatives, Fair Value [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 16 16
Commodity Option [Member]
    
Derivatives, Fair Value [Line Items]    
Derivative assets, current 471 339
Derivative Assets, Noncurrent 140 94
Total derivative assets 611 433
Current derivative liabilities 424 317
Derivative Liabilities, Noncurrent 237 133
Total derivative liabilities 661 450
Net derivative assets (liabilities) (50) (17)
Commodity Option [Member] | Not Designated as Hedging Instrument [Member]
    
Derivatives, Fair Value [Line Items]    
Total derivative assets 611 433
Total derivative liabilities $ 661 $ 450