Accounting for Derivative Instruments and Hedging Activities - Fair Value Within the Derivative Instrument Valuation (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
---|---|---|
Derivative [Line Items] | ||
Derivative assets | $ 1,170 | $ 1,081 |
Commodity contracts | 1,103 | 977 |
Interest rate contracts current | ||
Derivative [Line Items] | ||
Derivative assets | 0 | 17 |
Commodity contracts | 0 | 0 |
Interest rate contracts long-term | ||
Derivative [Line Items] | ||
Derivative assets | 0 | 22 |
Commodity contracts | 0 | 0 |
Commodity contracts current | ||
Derivative [Line Items] | ||
Derivative assets | 860 | 747 |
Commodity contracts | 781 | 673 |
Commodity contracts long-term | ||
Derivative [Line Items] | ||
Derivative assets | 310 | 295 |
Commodity contracts | $ 322 | $ 304 |