Accounting For Suspended Exploratory Well Costs (Narrative) (Details) $ in Millions |
Dec. 31, 2019
USD ($)
Projects
|
Dec. 31, 2018
USD ($)
Projects
|
Dec. 31, 2017
USD ($)
Projects
|
Dec. 31, 2016
USD ($)
|
|---|---|---|---|---|
| Exploratory Wells Drilled [Line Items] | ||||
| Number of projects that have exploratory well costs capitalized for a period of greater than one year | 46 | 52 | 46 | |
| Number of projects that have drilling in the preceding twelve months or exploratory activity planned in the next two years as of December 31, 2019 | 14 | |||
| Number of projects with completed exploratory activity progressing toward development as of December 31, 2019 | 32 | |||
| Capitalized exploratory well costs | $ | $ 4,613 | $ 4,160 | $ 3,700 | $ 4,477 |
| 32 Projects [Member] | ||||
| Exploratory Wells Drilled [Line Items] | ||||
| Capitalized exploratory well costs | $ | $ 3,176 |