Accounting for Derivative Instruments and Hedging Activities - Fair value within the derivative instrument valuation (Details) - USD ($) $ in Millions |
Mar. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Derivative [Line Items] | ||
| Derivative Liabilities | $ 2,440 | $ 884 |
| Not Designated as Hedging Instrument | ||
| Derivative [Line Items] | ||
| Derivative Assets | 2,824 | 821 |
| Derivative Liabilities | 2,440 | 884 |
| Not Designated as Hedging Instrument | Foreign exchange contracts - current | ||
| Derivative [Line Items] | ||
| Derivative Assets | 0 | 0 |
| Derivative Liabilities | 1 | 0 |
| Not Designated as Hedging Instrument | Foreign exchange contracts -long-term | ||
| Derivative [Line Items] | ||
| Derivative Assets | 0 | 0 |
| Derivative Liabilities | 1 | 0 |
| Not Designated as Hedging Instrument | Commodity contracts - current | ||
| Derivative [Line Items] | ||
| Derivative Assets | 1,816 | 560 |
| Derivative Liabilities | 1,605 | 499 |
| Not Designated as Hedging Instrument | Commodity contracts - long-term | ||
| Derivative [Line Items] | ||
| Derivative Assets | 1,008 | 261 |
| Derivative Liabilities | $ 833 | $ 385 |