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Capitalization of Exploratory Well Costs - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
3 Months Ended |
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Mar. 31, 2015
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| Capitalized Costs Relating To Oil And Gas Producing Activities By Geographic Area [Line Items] | |
| Accounting Standard Code for Extractive Industries followed for capitalization purposes - ASC Topic 932 | ASC Topic 932—Extractive Industries provides that the cost of an exploratory well shall be capitalized as part of the entity’s uncompleted wells pending the determination of whether the well has found proved reserves. Further, an exploration well that discovers oil and gas reserves, but for which reserves cannot be classified as proved when drilling is completed, shall be capitalized if the well has found a sufficient quantity of reserves to justify its completion as a producing well and the entity is making sufficient progress assessing the reserves and the economic and operating viability of the project. If either condition is not met, the exploration well that is not brought on to production would be assumed to be impaired and its costs would be charged to expense. |
| Mutamba Iroru | |
| Capitalized Costs Relating To Oil And Gas Producing Activities By Geographic Area [Line Items] | |
| Capitalization on development plan | 8.9 |