Derivative Instruments (Details 4) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
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| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Gain (Loss) on Derivative Instruments, Net, Pretax | [1] | $ 158 | $ 152 | $ 558 | $ 38 | ||||||||||||
| Gain (Loss) on Sale of Derivatives | [2],[3] | 92 | 45 | 261 | 111 | ||||||||||||
| Mark-to-market gain (loss) | [4] | 66 | 107 | 297 | (73) | ||||||||||||
| Sales [Member] | |||||||||||||||||
| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Gain (Loss) on Derivative Instruments, Net, Pretax | [1],[5],[6] | 213 | 34 | 791 | (142) | ||||||||||||
| Cost of Sales [Member] | |||||||||||||||||
| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Gain (Loss) on Derivative Instruments, Net, Pretax | [1],[5],[6] | (54) | 117 | (230) | 176 | ||||||||||||
| Interest Expense [Member] | |||||||||||||||||
| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Gain (Loss) on Derivative Instruments, Net, Pretax | [1] | (1) | 1 | (3) | 4 | ||||||||||||
| Interest Rate Hedging Instruments | |||||||||||||||||
| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Mark-to-market gain (loss) | [4] | (1) | 1 | (3) | 4 | ||||||||||||
| Energy Related Derivative [Member] | |||||||||||||||||
| Summary of Derivative Instruments by Risk Exposure [Abstract] | |||||||||||||||||
| Gain (Loss) on Sale of Derivatives | [2],[3] | 92 | 45 | 261 | 111 | ||||||||||||
| Mark-to-market gain (loss) | [4] | $ 67 | $ 106 | $ 300 | $ (77) | ||||||||||||
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