v2.4.0.8
Fair Value Fair Value of Derivative Contracts (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability, Fair Value, Amount Not Offset Against Collateral $ (274)   $ (311)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 343   357
Fair Value, Assets Liabilites Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Beginning of Period (110) (155)  
Total gains (losses), Included in earnings 7 5  
Total gains (losses), Included in other comprehensive income (1) (1)  
Settlements 4 9  
End of Period (100) (142)  
The amount of total gains or (losses) for the period included in earnings attributable to the change in unrealized gains or (losses) relating to assets held at the reporting date 3 (1)  
Quoted prices in active markets for identical assets (Level 1) [Member] | Commodity Contract [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (14)   (6)
Derivative Assets 6   4
Quoted prices in active markets for identical assets (Level 1) [Member] | Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability 0   0
Derivative Assets 0   0
Significant other observable inputs (Level 2) [Member] | Commodity Contract [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (50)   (31)
Derivative Assets 29   46
Significant other observable inputs (Level 2) [Member] | Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (94)   (116)
Derivative Assets 292   259
Significantunobservable inputs (Level 3) [Member] | Commodity Contract [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (116)   (158)
Derivative Assets 16   48
Significantunobservable inputs (Level 3) [Member] | Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability 0   0
Derivative Assets 0   0
Estimate of Fair Value [Member] | Commodity Contract [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (180)   (195)
Derivative Assets 51   98
Estimate of Fair Value [Member] | Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability (94)   (116)
Derivative Assets 292   259
Energy Related Derivative [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 11   36
Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 248   231
Not Offset on Balance Sheet [Member] | Energy Related Derivative [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Net Asset Adjustment for Financial Instruments subject to Master Netting Agreement but Presented Gross (40)   (62)
Derivative, Collateral, Obligation to Return Cash 0   0
Not Offset on Balance Sheet [Member] | Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Net Asset Adjustment for Financial Instruments subject to Master Netting Agreement but Presented Gross (44)   (28)
Derivative, Collateral, Obligation to Return Cash 0   0
Energy Related Derivative [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability, Fair Value, Amount Not Offset Against Collateral (118)   (116)
Energy Related Derivative [Member] | Not Offset on Balance Sheet [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Net Liability Adjustment for Financial Instruments Subject to Master Netting Agreement but Presented Gross 40   62
Derivative, Collateral, Right to Reclaim Cash 22   17
Interest Rate Swap [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Derivative Liability, Fair Value, Amount Not Offset Against Collateral (50)   (88)
Interest Rate Swap [Member] | Not Offset on Balance Sheet [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Net Liability Adjustment for Financial Instruments Subject to Master Netting Agreement but Presented Gross 44   28
Derivative, Collateral, Right to Reclaim Cash $ 0   $ 0