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Oil and Gas Producing Activities - Schedule of Information Regarding Costs Incurred for Oil and Gas Property Acquisition, Development and Exploration Activities (Parenthetical) (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items] |  |  |
Development costs | $ 43,202,000 | $ 15,884,000 | $ 146,237,000
Non-cash Asset Retirement Obligations [Member] |  |  |
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items] |  |  |
Development costs | $ 39,000 | $ 36,000 | $ 151,000

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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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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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