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Suspended Exploratory Well Costs - Additional Information (Detail) - USD ($) | Mar. 31, 2018 | Dec. 31, 2017
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Extractive Industries [Abstract] |  |
Suspended exploratory well costs | $ 0 | $ 0

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- Definition The amount of capitalized exploratory well costs that is pending the determination of proved reserves. This does not include amounts that were capitalized and subsequently expensed in the same annual period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447 + Details
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Balance Type: | debit
Period Type: | instant

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- References No definition available. + Details
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Balance Type: | na
Period Type: | duration