<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.8.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>753</ContextCount>
  <ElementCount>456</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>158</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/DocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1001501 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1002000 - Statement - CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ConsolidatedStatementsOfIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003000 - Statement - CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - ORGANIZATION AND BASIS OF PRESENTATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/OrganizationAndBasisOfPresentation</Role>
      <ShortName>ORGANIZATION AND BASIS OF PRESENTATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstruments</Role>
      <ShortName>FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - DUE TO PRIME BROKERS AND OTHER FINANCIAL INSTITUTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/DueToPrimeBrokersAndOtherFinancialInstitutions</Role>
      <ShortName>DUE TO PRIME BROKERS AND OTHER FINANCIAL INSTITUTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2105100 - Disclosure - CASH AND CASH EQUIVALENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CashAndCashEquivalents</Role>
      <ShortName>CASH AND CASH EQUIVALENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - RESTRICTED CASH AND CASH EQUIVALENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RestrictedCashAndCashEquivalents</Role>
      <ShortName>RESTRICTED CASH AND CASH EQUIVALENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReserves</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - RETROCESSION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/Retrocession</Role>
      <ShortName>RETROCESSION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - SHARE CAPITAL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareCapital</Role>
      <ShortName>SHARE CAPITAL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - SHARE-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensation</Role>
      <ShortName>SHARE-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - NET INVESTMENT INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/NetInvestmentIncome</Role>
      <ShortName>NET INVESTMENT INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2112100 - Disclosure - TAXATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/Taxation</Role>
      <ShortName>TAXATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2113100 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RelatedPartyTransactions</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2114100 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - SEGMENT REPORTING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SegmentReporting</Role>
      <ShortName>SEGMENT REPORTING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2116100 - Disclosure - QUARTERLY FINANCIAL RESULTS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/QuarterlyFinancialResultsUnaudited</Role>
      <ShortName>QUARTERLY FINANCIAL RESULTS (UNAUDITED)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2117100 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2118100 - Disclosure - SCHEDULE I</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleI</Role>
      <ShortName>SCHEDULE I</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2119100 - Disclosure - SCHEDULE II</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIi</Role>
      <ShortName>SCHEDULE II</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2120100 - Disclosure - SCHEDULE III</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIii</Role>
      <ShortName>SCHEDULE III</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2121100 - Disclosure - SCHEDULE IV</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIv</Role>
      <ShortName>SCHEDULE IV</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPoliciesPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2302302 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPoliciesTables</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/SignificantAccountingPolicies</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2303301 - Disclosure - FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsTables</Role>
      <ShortName>FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/FinancialInstruments</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2305301 - Disclosure - CASH AND CASH EQUIVALENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CashAndCashEquivalentsTables</Role>
      <ShortName>CASH AND CASH EQUIVALENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/CashAndCashEquivalents</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - RESTRICTED CASH AND CASH EQUIVALENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RestrictedCashAndCashEquivalentsTables</Role>
      <ShortName>RESTRICTED CASH AND CASH EQUIVALENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/RestrictedCashAndCashEquivalents</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2307302 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Loss Development (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesLossDevelopmentTables</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Loss Development (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2307303 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Short-duration Insurance Contacts, Reconciliation of claims tables to Liability (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesShortDurationInsuranceContactsReconciliationOfClaimsTablesToLiabilityTables</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Short-duration Insurance Contacts, Reconciliation of claims tables to Liability (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2307304 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Historical claim payout duration (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesHistoricalClaimPayoutDurationTables</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Historical claim payout duration (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - SHARE CAPITAL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareCapitalTables</Role>
      <ShortName>SHARE CAPITAL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ShareCapital</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - SHARE-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationTables</Role>
      <ShortName>SHARE-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ShareBasedCompensation</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2311301 - Disclosure - NET INVESTMENT INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/NetInvestmentIncomeTables</Role>
      <ShortName>NET INVESTMENT INCOME (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/NetInvestmentIncome</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2312301 - Disclosure - TAXATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/TaxationTables</Role>
      <ShortName>TAXATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/Taxation</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2313301 - Disclosure - RELATED PARTY TRANSACTIONS Non Controlling Interest (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RelatedPartyTransactionsNonControllingInterestTables</Role>
      <ShortName>RELATED PARTY TRANSACTIONS Non Controlling Interest (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2314301 - Disclosure - COMMITMENTS AND CONTINGENCIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CommitmentsAndContingenciesTables</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/CommitmentsAndContingencies</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2315301 - Disclosure - SEGMENT REPORTING (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SegmentReportingTables</Role>
      <ShortName>SEGMENT REPORTING (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/SegmentReporting</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2316301 - Disclosure - QUARTERLY FINANCIAL RESULTS (UNAUDITED) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/QuarterlyFinancialResultsUnauditedTables</Role>
      <ShortName>QUARTERLY FINANCIAL RESULTS (UNAUDITED) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/QuarterlyFinancialResultsUnaudited</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2319301 - Disclosure - SCHEDULE II (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIiTables</Role>
      <ShortName>SCHEDULE II (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ScheduleI</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2401401 - Disclosure - ORGANIZATION AND BASIS OF PRESENTATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/OrganizationAndBasisOfPresentationDetails</Role>
      <ShortName>ORGANIZATION AND BASIS OF PRESENTATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/OrganizationAndBasisOfPresentation</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2402403 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPoliciesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/SignificantAccountingPoliciesTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2402405 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES Earnings Per Share Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPoliciesEarningsPerShareReconciliationDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES Earnings Per Share Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2402406 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES Income taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SignificantAccountingPoliciesIncomeTaxesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES Income taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - FINANCIAL INSTRUMENTS Financial Instruments Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsFinancialInstrumentsAdditionalInformationDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Financial Instruments Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2403403 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Investments Categorized by the Level of Fair Value Hierarchy (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfInvestmentsCategorizedByLevelOfFairValueHierarchyDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Investments Categorized by the Level of Fair Value Hierarchy (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2403404 - Disclosure - FINANCIAL INSTRUMENTS Fair Value Hierarchy Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsFairValueHierarchyAdditionalInformationDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Fair Value Hierarchy Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2403405 - Disclosure - FINANCIAL INSTRUMENTS Level 3 reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsLevel3ReconciliationDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Level 3 reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2403406 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Investments Included in Debt Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfInvestmentsIncludedInDebtInstrumentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Investments Included in Debt Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2403407 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Maturity Distribution of Debt Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfMaturityDistributionOfDebtInstrumentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Maturity Distribution of Debt Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2403408 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Investments in Equity Securities, Trading (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfInvestmentsInEquitySecuritiesTradingDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Investments in Equity Securities, Trading (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2403409 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Other Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfOtherInvestmentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Other Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2403410 - Disclosure - FINANCIAL INSTRUMENTS NAV Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsNavInstrumentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS NAV Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2403411 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Investments in Securities Sold, Not Yet Purchased (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfInvestmentsInSecuritiesSoldNotYetPurchasedDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Investments in Securities Sold, Not Yet Purchased (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2403412 - Disclosure - FINANCIAL INSTRUMENTS Financial Contracts Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsFinancialContractsAdditionalInformationDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Financial Contracts Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2403413 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Fair Values of Financial Contracts Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfFairValuesOfFinancialContractsOutstandingDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Fair Values of Financial Contracts Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2403414 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Reported Gains and Losses on Derivatives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfReportedGainsAndLossesOnDerivativesDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Reported Gains and Losses on Derivatives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2403415 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Volume of Derivative Activities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfVolumeOfDerivativeActivitiesDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Volume of Derivative Activities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2403416 - Disclosure - FINANCIAL INSTRUMENTS Schedule of Gross and Net Amounts of Derivative Instruments and Cash Collateral (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/FinancialInstrumentsScheduleOfGrossAndNetAmountsOfDerivativeInstrumentsAndCashCollateralDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS Schedule of Gross and Net Amounts of Derivative Instruments and Cash Collateral (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2404401 - Disclosure - DUE TO PRIME BROKERS AND OTHER FINANCIAL INSTITUTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/DueToPrimeBrokersAndOtherFinancialInstitutionsDetails</Role>
      <ShortName>DUE TO PRIME BROKERS AND OTHER FINANCIAL INSTITUTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/DueToPrimeBrokersAndOtherFinancialInstitutions</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>2405402 - Disclosure - CASH AND CASH EQUIVALENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CashAndCashEquivalentsDetails</Role>
      <ShortName>CASH AND CASH EQUIVALENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/CashAndCashEquivalentsTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - RESTRICTED CASH AND CASH EQUIVALENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RestrictedCashAndCashEquivalentsDetails</Role>
      <ShortName>RESTRICTED CASH AND CASH EQUIVALENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/RestrictedCashAndCashEquivalentsTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>2407401 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Liabilities for loss reserves (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesLiabilitiesForLossReservesDetails</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Liabilities for loss reserves (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>2407405 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesDetails</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesLossDevelopmentTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>2407406 - Disclosure - LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Loss development tables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/LossAndLossAdjustmentExpenseReservesLossDevelopmentTablesDetails</Role>
      <ShortName>LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Loss development tables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>2408401 - Disclosure - RETROCESSION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RetrocessionDetails</Role>
      <ShortName>RETROCESSION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/Retrocession</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - SHARE CAPITAL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareCapitalDetails</Role>
      <ShortName>SHARE CAPITAL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ShareCapitalTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - SHARE-BASED COMPENSATION Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationNarrativeDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>2410403 - Disclosure - SHARE-BASED COMPENSATION Restricted Shares (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationRestrictedSharesDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION Restricted Shares (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>2410404 - Disclosure - SHARE-BASED COMPENSATION Black Scholes option pricing model assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationBlackScholesOptionPricingModelAssumptionsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION Black Scholes option pricing model assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>2410405 - Disclosure - SHARE-BASED COMPENSATION Share Based Compensation Options Rollfoward (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationShareBasedCompensationOptionsRollfowardDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION Share Based Compensation Options Rollfoward (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>2410406 - Disclosure - SHARE-BASED COMPENSATION Restricted Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ShareBasedCompensationRestrictedUnitsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION Restricted Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - NET INVESTMENT INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/NetInvestmentIncomeDetails</Role>
      <ShortName>NET INVESTMENT INCOME (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/NetInvestmentIncomeTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>2412402 - Disclosure - TAXATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/TaxationDetails</Role>
      <ShortName>TAXATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/TaxationTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>2413402 - Disclosure - RELATED PARTY TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/RelatedPartyTransactionsDetails</Role>
      <ShortName>RELATED PARTY TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/RelatedPartyTransactionsNonControllingInterestTables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>2414402 - Disclosure - COMMITMENTS AND CONTINGENCIES Letters of Credit (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CommitmentsAndContingenciesLettersOfCreditDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES Letters of Credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>2414403 - Disclosure - COMMITMENTS AND CONTINGENCIES Lease and commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CommitmentsAndContingenciesLeaseAndCommitmentsDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES Lease and commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>2414404 - Disclosure - COMMITMENTS AND CONTINGENCIES Revolving Credit Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/CommitmentsAndContingenciesRevolvingCreditFacilityDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES Revolving Credit Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>2415402 - Disclosure - SEGMENT REPORTING Schedule of Revenue by Major Customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SegmentReportingScheduleOfRevenueByMajorCustomersDetails</Role>
      <ShortName>SEGMENT REPORTING Schedule of Revenue by Major Customers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>2415403 - Disclosure - SEGMENT REPORTING Schedule of Gross Premiums Written by Line of Business (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SegmentReportingScheduleOfGrossPremiumsWrittenByLineOfBusinessDetails</Role>
      <ShortName>SEGMENT REPORTING Schedule of Gross Premiums Written by Line of Business (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>2415404 - Disclosure - SEGMENT REPORTING Geographic information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SegmentReportingGeographicInformationDetails</Role>
      <ShortName>SEGMENT REPORTING Geographic information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>2416402 - Disclosure - QUARTERLY FINANCIAL RESULTS (UNAUDITED) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/QuarterlyFinancialResultsUnauditedDetails</Role>
      <ShortName>QUARTERLY FINANCIAL RESULTS (UNAUDITED) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/QuarterlyFinancialResultsUnauditedTables</ParentRole>
      <Position>86</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>2417401 - Disclosure - SUBSEQUENT EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/SubsequentEventsDetails</Role>
      <ShortName>SUBSEQUENT EVENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/SubsequentEvents</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>2418401 - Disclosure - SCHEDULE I (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIDetails</Role>
      <ShortName>SCHEDULE I (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ScheduleIiTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>2419402 - Disclosure - SCHEDULE II Condensed Balance Sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIiCondensedBalanceSheetsDetails</Role>
      <ShortName>SCHEDULE II Condensed Balance Sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>2419403 - Disclosure - SCHEDULE II Condensed Statements of Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIiCondensedStatementsOfIncomeDetails</Role>
      <ShortName>SCHEDULE II Condensed Statements of Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>2419404 - Disclosure - SCHEDULE II Condensed Statements of Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIiCondensedStatementsOfCashFlowsDetails</Role>
      <ShortName>SCHEDULE II Condensed Statements of Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>2420401 - Disclosure - SCHEDULE III (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIiiDetails</Role>
      <ShortName>SCHEDULE III (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ScheduleIiTables</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="glre-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>2421401 - Disclosure - SCHEDULE IV (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.greenlightre.ky/role/ScheduleIvDetails</Role>
      <ShortName>SCHEDULE IV (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.greenlightre.ky/role/ScheduleIiTables</ParentRole>
      <Position>93</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>glre-20171231.xml</File>
    <File>glre-20171231.xsd</File>
    <File>glre-20171231_cal.xml</File>
    <File>glre-20171231_def.xml</File>
    <File>glre-20171231_lab.xml</File>
    <File>glre-20171231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2014-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/invest/2013-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/exch/2017-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
