cm:Level2TextBlock: us-gaap:ExploratoryDrillingCostsCapitalizationAndImpairmentPolicy
| Exploratory Drilling Costs Capitalization and Impairment, Policy [Policy Text Block] |
| us-gaap:ExploratoryDrillingCostsCapitalizationAndImpairmentPolicy |
| Disclosure of accounting policy for capitalization of exploratory drilling costs, including the criteria management applies in evaluating whether costs incurred meet the criteria for initial capitalization, continued capitalization, impairment, and how often such evaluations are made. |
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| us-gaap:ExploratoryDrillingCostsCapitalizationAndImpairmentPolicy |