v3.8.0.1

Disclosures About Oil and Gas Producing Activities - Summary of Changes in Quantities of Proved Oil, NGL and Natural Gas Reserves (Detail) | 12 Months Ended
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Dec. 31, 2017 MBoe MBbls MMcf | Dec. 31, 2016 MBoe MBbls MMcf | Dec. 31, 2015 MBoe MBbls MMcf
Reserve Quantities [Line Items] |  |  |
Production | MMcf | (1,319) | (1,330) | (1,530)
Proved Developed and Proved Undeveloped Reserves, Beginning Balance | MBoe | 156,377 | 166,646 | 146,248
Extensions and discoveries | MBoe | 33,307 | 16,651 | 34,895
Acquisition of minerals in place | MBoe | 1,572 |  |
Production | MBoe | (4,452) | (4,759) | (5,787)
Revisions to previous estimates | MBoe | (5,259) | (22,161) | (8,710)
Proved Developed and Proved Undeveloped Reserves, Ending Balance | MBoe | 181,545 | 156,377 | 166,646
Oil (MBbls) [Member] |  |  |
Reserve Quantities [Line Items] |  |  |
Proved Developed and Proved Undeveloped Reserves, Beginning Balance | 50,031 | 54,496 | 55,338
Extensions and discoveries | 10,546 | 6,529 | 11,054
Acquisition of minerals in place | 710 |  |
Production | (1,107) | (1,275) | (1,882)
Revisions to previous estimates | (10,120) | (9,719) | (10,014)
Proved Developed and Proved Undeveloped Reserves, Ending Balance | 50,060 | 50,031 | 54,496
NGLs (MBbls) [Member] |  |  |
Reserve Quantities [Line Items] |  |  |
Proved Developed and Proved Undeveloped Reserves, Beginning Balance | 47,634 | 49,486 | 40,907
Extensions and discoveries | 9,975 | 4,564 | 10,630
Acquisition of minerals in place | 394 |  |
Production | (1,486) | (1,529) | (1,694)
Revisions to previous estimates | 1,431 | (4,887) | (357)
Proved Developed and Proved Undeveloped Reserves, Ending Balance | 57,948 | 47,634 | 49,486
Natural Gas (MMcf) [Member] |  |  |
Reserve Quantities [Line Items] |  |  |
Proved Developed and Proved Undeveloped Reserves, Beginning Balance | MMcf | 352,277 | 375,988 | 300,020
Extensions and discoveries | MMcf | 76,710 | 33,347 | 79,268
Acquisition of minerals in place | MMcf | 2,808 |  |
Production | MMcf | (11,148) | (11,734) | (13,262)
Revisions to previous estimates | MMcf | 20,581 | (45,324) | 9,962
Proved Developed and Proved Undeveloped Reserves, Ending Balance | MMcf | 441,228 | 352,277 | 375,988

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- Definition Energy measure of increase in quantity of proved reserve of oil and gas resulting from the extension of the proved acreage of previously discovered reservoir or discovery of new field with proved reserve or of new reservoir of proved reserve in old field, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition Energy measure of proved reserve of oil and gas, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition Energy measure of decrease in quantity of proved reserve of oil and gas resulting from production, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition Energy measure of increase in quantity of proved reserve of oil and gas resulting from purchase of mineral in place, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition Energy measure of increase (decrease) in quantity of proved reserve of oil and gas related to revision of a previous estimate resulting from new information, except for an increase in proved acreage, or change in economic factors, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition Additions to proved reserves that result from (1) extension of the proved acreage of previously discovered (old) reservoirs through additional drilling in periods after discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition The net quantity of proved reserves as of the balance sheet date. Proved oil reserves are the estimated quantities of crude oil and natural gas liquids which geological and engineering data demonstrate with reasonable certainty to be recoverable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10.(a)(2)) -URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862 + Details
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- Definition Revisions represent changes in previous estimates of proved reserves, either upward or downward, resulting from new information (except for an increase in proved acreage) normally obtained from development drilling and production history or resulting from change in economic factors. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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