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Supplementary Information - Costs Incurred in Oil and Gas Property Acquisition, Exploration and Development Activities (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |
Development Costs | $ 59,361 | $ 20,843

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- Definition Development costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 18 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62014-109447 + Details
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- References No definition available. + Details
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