Investment in Cenovus Energy - Gains and Losses Recorded in Other Income (Loss) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Debt and Equity Securities, FV-NI [Line Items] | ||||
| Total net gain (loss) on CVE common shares | $ 743 | $ (1,302) | ||
| Cenovus Energy Inc [Member] | ||||
| Debt and Equity Securities, FV-NI [Line Items] | ||||
| Total net gain (loss) on CVE common shares | $ 17 | $ (162) | 743 | (1,302) |
| Less: Net gain on equity securities sold during the period | (50) | 0 | 177 | 0 |
| Unrealized gain (loss) on equity securities still held at the reporting date | $ 67 | $ (162) | $ 566 | $ (1,302) |