Impairments - Before Tax Impairment Charges (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Mar. 31, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Segment Reporting Information [Line Items] | |||||
| Impairments | $ (89) | $ 2 | $ (90) | $ 521 | |
| Alaska Segment [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| Impairments | 0 | 0 | 3 | 0 | |
| Lower 48 [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| Impairments | (89) | 1 | $ 511 | (93) | 514 |
| Europe, Middle East and North Africa [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| Impairments | $ 0 | $ 1 | $ 0 | $ 7 | |