Investment in Cenovus Energy - Textual (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2020 |
Dec. 31, 2020 |
|
| Debt and Equity Securities, FV-NI [Line Items] | |||||
| Investment in Cenovus Energy | $ 1,802 | $ 1,802 | $ 1,256 | ||
| Cenovus Energy Inc [Member] | |||||
| Debt and Equity Securities, FV-NI [Line Items] | |||||
| (Gain) loss on investment in Cenovus Energy | (387) | $ (551) | (666) | $ 1,140 | |
| Common Stock [Member] | Cenovus Energy Inc [Member] | |||||
| Debt and Equity Securities, FV-NI [Line Items] | |||||
| Investment in equity security, fair value | $ 1,800 | $ 1,800 | |||
| Shares exchanged for assets held for sale | 188 | 188 | 208 | ||
| Investment owned, common stock, percent of issued and outstanding | 9.30% | 9.30% | |||
| Cenovus Energy common share price | $ 9.58 | $ 9.58 | |||
| Equity securities, shares sold | 20 | ||||
| Proceeds recognized from sale of equity securities | $ 180 | ||||
| Proceeds received from sale of equity securities | $ 166 | ||||