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Property, Plant And Equipment (Net Changes in Capitalized Exploratory Well Costs) (Details) - USD ($) | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Property, Plant And Equipment [Abstract] |  |
Beginning balance at January 1 | $ 175,640,000 | $ 148,500,000
Additions pending the determination of proved reserves | 623,000 | 39,653,000
Reclassifications to proved properties based on the determination of proved reserves |  | (13,370,000)
Capitalized exploratory well costs charged to expense | 0 | (8,360,000)
Ending balance at March 31 | $ 176,263,000 | $ 166,423,000

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- Definition Additions to capitalized exploratory well costs that were added during the reporting period pending the determination of proved reserves. + 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)(1) -URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447 + Details
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- Definition Amount of expense for capitalized exploratory well costs for which proved reserves were not found at the exploratory well. + 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)(3) -URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447 + Details
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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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- References No definition available. + Details
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- Definition Previously capitalized costs of the drilling of wells that were reclassified as part of the costs of the enterprise's wells and related equipment and facilities at the time that proved reserves were found. + 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)(2) -URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447 + Details
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