2.4.0.80037 - Disclosure - Price risk management activities (Details)truefalsefalse1false USDfalsefalseFrom2013-01-01to2013-06-30_SwapMemberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0$2false USDfalsefalse$From2012-01-01to2012-12-31_us-gaap_SwapMemberhttp://www.sec.gov/CIK0001373485duration2012-01-01T00:00:002012-12-31T00:00:00USDPUnitsDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancepurexbrli0MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1truefalsefalse155744155744[1],[2]USD$falsetruefalse2truefalsefalse290788290788[1],[2]USD$falsetruefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts2false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3false USDtruefalseFrom2013-01-01to2013-06-30_SwapMemberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseMarch 2011 Swapus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_SwapMemberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0$nanafalse0March 2011 Swap3false 4us-gaap_DerivativeInceptionDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-04-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the entity entered into the derivative contract, in CCYY-MM-DD format.No definition available.false0Beginning Date4false 4us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-02-28[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Ending Date5false 4us-gaap_UnderlyingDerivativeAssetus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse104.55104.55falsefalsefalseus-types:perUnitItemTypedecimalSpecified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative asset contract but not the derivative contract itself.No definition available.false0Price Per Unit6false 4XBOR_ContractVolume1XBOR_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse10001000[1]falsefalsefalsenum:volumeItemTypedecimalThe volume of a commodity or material specified in a contract.No definition available.false256Volumes Per Month7false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1falsefalsefalse00  [1],[2]USD$falsefalsefalse2truefalsefalse4101941019[1],[2]USD$falsefalsefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts8false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse5false USDtruefalseFrom2013-01-01to2013-06-30_Swap1Memberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseNovember 2011 Swapus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldiXBOR_Swap1Memberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0$nanafalse0November 2011 Swap9false 4us-gaap_DerivativeInceptionDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-12-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the entity entered into the derivative contract, in CCYY-MM-DD format.No definition available.false0Beginning Date10false 4us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002014-11-30[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Ending Date11false 4us-gaap_UnderlyingDerivativeAssetus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse93.5093.50falsefalsefalseus-types:perUnitItemTypedecimalSpecified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative asset contract but not the derivative contract itself.No definition available.false0Price Per Unit12false 4XBOR_ContractVolume1XBOR_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse20002000[1]falsefalsefalsenum:volumeItemTypedecimalThe volume of a commodity or material specified in a contract.No definition available.false256Volumes Per Month13false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1falsefalsefalse00  [1],[2]USD$falsefalsefalse2truefalsefalse4494244942[1],[2]USD$falsefalsefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts14false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse7false USDtruefalseFrom2013-01-01to2013-06-30_Swap2Memberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFebruary 2012 Swapus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldiXBOR_Swap2Memberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0$nanafalse0February 2012 Swap15false 4us-gaap_DerivativeInceptionDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002012-03-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the entity entered into the derivative contract, in CCYY-MM-DD format.No definition available.false0Beginning Date16false 4us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002014-02-28[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Ending Date17false 4us-gaap_UnderlyingDerivativeAssetus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse106.50106.50falsefalsefalseus-types:perUnitItemTypedecimalSpecified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative asset contract but not the derivative contract itself.No definition available.false0Price Per Unit18false 4XBOR_ContractVolume1XBOR_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse10001000[1]falsefalsefalsenum:volumeItemTypedecimalThe volume of a commodity or material specified in a contract.No definition available.false256Volumes Per Month19false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1falsefalsefalse00  [1],[2]USD$falsefalsefalse2truefalsefalse204827204827[1],[2]USD$falsefalsefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts20false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse9false USDtruefalse$From2013-01-01to2013-06-30_custom_Swap3Memberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFebruary 2013 Swapus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldiXBOR_Swap3Memberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMemberUSDPUnitsDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancepurexbrli0MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0February 2013 Swap21false 4us-gaap_DerivativeInceptionDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-03-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the entity entered into the derivative contract, in CCYY-MM-DD format.No definition available.false0Beginning Date22false 4us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002014-11-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Ending Date23false 4us-gaap_UnderlyingDerivativeAssetus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse93.5093.50falsefalsefalse2falsefalsefalse00falsefalsefalseus-types:perUnitItemTypedecimalSpecified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative asset contract but not the derivative contract itself.No definition available.false0Price Per Unit24false 4XBOR_ContractVolume1XBOR_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse20002000[1]falsefalsefalse2falsefalsefalse00falsefalsefalsenum:volumeItemTypedecimalThe volume of a commodity or material specified in a contract.No definition available.false256Volumes Per Month25false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1truefalsefalse4857048570[1],[2]USD$falsefalsefalse2falsefalsefalse00  [1],[2]USD$falsefalsefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts26false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse11false USDtruefalse$From2013-01-01to2013-06-30_custom_Swap4Memberhttp://www.sec.gov/CIK0001373485duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFebruary 2013 Swap 2us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldiXBOR_Swap4Memberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMemberUSDPUnitsDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancepurexbrli0MBblsStandardhttp://www.xbrl.org/2009/utrMMBblsutr0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0February 2013 Swap 227false 4us-gaap_DerivativeInceptionDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-03-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the entity entered into the derivative contract, in CCYY-MM-DD format.No definition available.false0Beginning Date28false 4us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002014-02-01[1]falsefalsetrue2falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Ending Date29false 4us-gaap_UnderlyingDerivativeAssetus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse106.50106.50falsefalsefalse2falsefalsefalse00falsefalsefalseus-types:perUnitItemTypedecimalSpecified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative asset contract but not the derivative contract itself.No definition available.false0Price Per Unit30false 4XBOR_ContractVolume1XBOR_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse10001000[1]falsefalsefalse2falsefalsefalse00falsefalsefalsenum:volumeItemTypedecimalThe volume of a commodity or material specified in a contract.No definition available.false256Volumes Per Month31false 4us-gaap_DerivativeLiabilitiesus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1truefalsefalse107174107174[1],[2]USD$falsetruefalse2falsefalsefalse00  [1],[2]USD$falsefalsefalsexbrli:monetaryItemTypemonetaryFair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 false2Fair Value of Outstanding Derivatives Contracts1These crude oil hedges were entered into on a per barrel delivered price basis, using the NYMEX - West Texas Intermediate Index, with settlement for each calendar month occuring following the expiration date, as determined by the contracts.2The fair value of the Company's outstanding transactions is presented on the balance sheet by counterparty. Currently all of our derivatives are with the same counterparty. The balance is shown as current or long-term based on our estimates of the amounts that will be due in the relevant time periods at currently predicted price levels. Amounts in parentheses indicate liabilities.falsePrice risk management activities (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://xbres.com/role/PriceRiskManagementActivitiesDetails231