Investment in Cenovus Energy (Gains and Losses Recorded in Other Income (Loss)) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Debt and Equity Securities, FV-NI [Line Items] | |||
| Total Net gain (loss) on equity securtities | $ 1,040 | $ (855) | $ 649 |
| Cenovus Energy Inc [Member] | |||
| Debt and Equity Securities, FV-NI [Line Items] | |||
| Total Net gain (loss) on equity securtities | 1,040 | (855) | 649 |
| Less: Net gain (loss) on equity securities sold during the period | 473 | ||
| Unrealized gain (loss) on equity securities still held at the reporting date | $ 567 | $ (855) | $ 649 |