cm:Level3TextBlock: us-gaap:ScheduleOfProjectsWithExploratoryWellCostsCapitalizedForMoreThanOneYearTextBlock
| Schedule of Projects with Exploratory Well Costs Capitalized for More than One Year [Table Text Block] |
| us-gaap:ScheduleOfProjectsWithExploratoryWellCostsCapitalizedForMoreThanOneYearTextBlock |
| Tabular disclosure of exploratory well costs that continue to be capitalized for more than one year after the completion of drilling. Information may include a description of the projects and the activities that the enterprise has undertaken to date in order to evaluate the reserves and the projects, and the remaining activities required to classify the associated reserves as proved. |
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| us-gaap:ScheduleOfProjectsWithExploratoryWellCostsCapitalizedForMoreThanOneYearTextBlock |