v3.7.0.1
Derivative Instruments (Details 2) (Details) - USD ($)
$ in Millions
Mar. 31, 2017
Dec. 31, 2016
Derivatives, Fair Value [Line Items]    
Derivative assets, current $ 1,387 $ 1,725
Long-term derivative assets 670 543
Total derivative assets 2,057 2,268
Derivative liabilities, current 1,273 1,630
Long-term derivative liabilities 550 476
Total derivative liabilities 1,823 2,106
Derivative, Fair Value, Net 234 162
Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Total derivative assets 37 29
Total derivative liabilities 55 58
Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Total derivative assets 2,020 2,239
Total derivative liabilities 1,768 2,048
Interest Rate Hedging Instruments    
Derivatives, Fair Value [Line Items]    
Derivative assets, current 1 1
Derivative Assets, Noncurrent 36 28
Total derivative assets 37 29
Current derivative liabilities 27 28
Derivative Liabilities, Noncurrent 28 30
Total derivative liabilities 55 58
Derivative, Fair Value, Net (18) (29)
Interest Rate Hedging Instruments | Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Total derivative assets 37 29
Total derivative liabilities 55 58
Energy Related Derivative [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets, current 1,386 1,724
Derivative Assets, Noncurrent 634 515
Total derivative assets 2,020 2,239
Current derivative liabilities 1,246 1,602
Derivative Liabilities, Noncurrent 522 446
Total derivative liabilities 1,768 2,048
Derivative, Fair Value, Net 252 191
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Total derivative assets 2,020 2,239
Total derivative liabilities $ 1,768 $ 2,048