<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.2.0.7</Version>
  <MyReports>
    <Report>
      <IsDefault>true</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ShortName>Document and Entity Information</ShortName>
      <Role>http://www.grantierra.com/role/DocumentDocumentAndEntityInformation</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R1.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00100 - Statement - Condensed Consolidated Statements of Operations and Retained Earnings (Accumulated Deficit)</LongName>
      <ShortName>Condensed Consolidated Statements of Operations and Retained Earnings (Accumulated Deficit)</ShortName>
      <Role>http://www.grantierra.com/role/StatementCondensedConsolidatedStatementsOfOperationsAndRetainedEarningsAccumulatedDeficit</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R2.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00200 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <Role>http://www.grantierra.com/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R3.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00210 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <Role>http://www.grantierra.com/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R4.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00300 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <Role>http://www.grantierra.com/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R5.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00400 - Statement - Condensed Consolidated Statements of Shareholders' Equity</LongName>
      <ShortName>Condensed Consolidated Statements of Shareholders' Equity</ShortName>
      <Role>http://www.grantierra.com/role/StatementCondensedConsolidatedStatementsOfShareholdersEquity</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R6.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10101 - Disclosure - Description of Business</LongName>
      <ShortName>Description of Business</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureDescriptionOfBusiness</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R7.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10201 - Disclosure - Significant Accounting Policies</LongName>
      <ShortName>Significant Accounting Policies</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureSignificantAccountingPolicies</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R8.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10301 - Disclosure - Segment and Geographic Reporting</LongName>
      <ShortName>Segment and Geographic Reporting</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureSegmentAndGeographicReporting</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R9.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10401 - Disclosure - Property, Plant and Equipment</LongName>
      <ShortName>Property, Plant and Equipment</ShortName>
      <Role>http://www.grantierra.com/role/DisclosurePropertyPlantAndEquipment</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R10.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10501 - Disclosure - Share Capital</LongName>
      <ShortName>Share Capital</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureShareCapital</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R11.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10601 - Disclosure - Asset Retirement Obligation</LongName>
      <ShortName>Asset Retirement Obligation</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureAssetRetirementObligation</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R12.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10701 - Disclosure - Income Taxes</LongName>
      <ShortName>Income Taxes</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureIncomeTaxes</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R13.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10801 - Disclosure - Accounts Payable and Accrued Liabilities</LongName>
      <ShortName>Accounts Payable and Accrued Liabilities</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureAccountsPayableAndAccruedLiabilities</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R14.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>10901 - Disclosure - Commitments and Contingencies</LongName>
      <ShortName>Commitments and Contingencies</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R15.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>11001 - Disclosure - Financial Instruments, Fair Value Measurements and Credit Risk</LongName>
      <ShortName>Financial Instruments, Fair Value Measurements and Credit Risk</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureFinancialInstrumentsFairValueMeasurementsAndCreditRisk</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R16.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>11101 - Disclosure - Credit Facilities</LongName>
      <ShortName>Credit Facilities</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureCreditFacilities</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R17.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>11201 - Disclosure - Related Party Transactions</LongName>
      <ShortName>Related Party Transactions</ShortName>
      <Role>http://www.grantierra.com/role/DisclosureRelatedPartyTransaction</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R18.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Book</ReportType>
      <LongName>All Reports</LongName>
      <ShortName>All Reports</ShortName>
      <Role />
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName />
    </Report>
  </MyReports>
  <EntityCount>1</EntityCount>
  <ContextCount>34</ContextCount>
  <SegmentCount>6</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <UnitCount>3</UnitCount>
  <ElementCount>109</ElementCount>
  <FootnotesReported>false</FootnotesReported>
  <TuplesReported>false</TuplesReported>
  <ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_2009</ContextName>
      <ElementCount>41</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_12_31_20093</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_12_31_20095</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20084</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20092</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_20105</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_9_30_2009</ContextName>
      <ElementCount>37</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_2008</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_20102</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_7_1_2010_To_9_30_2010</ContextName>
      <ElementCount>15</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_6_30_2010</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2010_To_9_30_20102</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2010_To_9_30_201032</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_20103</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2010_To_9_30_20103</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20085</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_12_31_20094</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20094</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20083</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_2009</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20095</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20082</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_6_30_2009</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_11_2_2010</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_12_31_20092</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_20104</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_11_2_20102</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2010_To_9_30_2010</ContextName>
      <ElementCount>59</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_11_2_20103</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_7_1_2009_To_9_30_2009</ContextName>
      <ElementCount>16</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_9_30_2010</ContextName>
      <ElementCount>42</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2010_To_9_30_20104</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>Duration_1_1_2009_To_12_31_2009</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>As_Of_12_31_20093</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
  </ContextSummary>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
