<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>386</ContextCount>
  <ElementCount>530</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>123</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONSOLIDATED INCOME STATEMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedIncomeStatements</Role>
      <ShortName>CONSOLIDATED INCOME STATEMENTS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - CONSOLIDATED INCOME STATEMENTS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedIncomeStatementsParenthetical</Role>
      <ShortName>CONSOLIDATED INCOME STATEMENTS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL POSITION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedStatementsOfFinancialPosition</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF FINANCIAL POSITION</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN EQUITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedStatementsOfChangesInEquities</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN EQUITIES</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00500 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOW</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/StatementConsolidatedStatementsOfCashFlow</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOW</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - DESCRIPTION OF BUSINESS AND NATURE OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDescriptionOfBusinessAndNatureOfOperations</Role>
      <ShortName>DESCRIPTION OF BUSINESS AND NATURE OF OPERATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPolicies</Role>
      <ShortName>BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - CRITICAL JUDGMENTS AND ESTIMATION UNCERTAINTIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCriticalJudgmentsAndEstimationUncertainties</Role>
      <ShortName>CRITICAL JUDGMENTS AND ESTIMATION UNCERTAINTIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - REVISIONS TO PRIOR PERIOD COMPARATIVES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureRevisionsToPriorPeriodComparatives</Role>
      <ShortName>REVISIONS TO PRIOR PERIOD COMPARATIVES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10601 - Disclosure - TRADE AND OTHER RECEIVABLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherReceivables</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10701 - Disclosure - TRADE AND OTHER PAYABLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherPayables</Role>
      <ShortName>TRADE AND OTHER PAYABLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10801 - Disclosure - INVENTORIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureInventories</Role>
      <ShortName>INVENTORIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10901 - Disclosure - MINING INTERESTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureMiningInterests</Role>
      <ShortName>MINING INTERESTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>11001 - Disclosure - IMPAIRMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureImpairment</Role>
      <ShortName>IMPAIRMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11101 - Disclosure - LONG-TERM DEBT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebt</Role>
      <ShortName>LONG-TERM DEBT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11201 - Disclosure - GOLD STREAM OBLIGATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureGoldStreamObligation</Role>
      <ShortName>GOLD STREAM OBLIGATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11301 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLeases</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11401 - Disclosure - DERIVATIVE INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstruments</Role>
      <ShortName>DERIVATIVE INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11501 - Disclosure - SHARE CAPITAL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapital</Role>
      <ShortName>SHARE CAPITAL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11601 - Disclosure - DISCONTINUED OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDiscontinuedOperations</Role>
      <ShortName>DISCONTINUED OPERATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11701 - Disclosure - INCOME AND MINING TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxes</Role>
      <ShortName>INCOME AND MINING TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>11801 - Disclosure - RECLAMATION AND CLOSURE COST OBLIGATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligations</Role>
      <ShortName>RECLAMATION AND CLOSURE COST OBLIGATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>11901 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSupplementalCashFlowInformation</Role>
      <ShortName>SUPPLEMENTAL CASH FLOW INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>12001 - Disclosure - SEGMENTED INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformation</Role>
      <ShortName>SEGMENTED INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>12101 - Disclosure - CAPITAL RISK MANAGEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCapitalRiskManagement</Role>
      <ShortName>CAPITAL RISK MANAGEMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>12201 - Disclosure - FINANCIAL RISK MANAGEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagement</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>12301 - Disclosure - FAIR VALUE MEASUREMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFairValueMeasurement</Role>
      <ShortName>FAIR VALUE MEASUREMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>12401 - Disclosure - COMPENSATION OF KEY MANAGEMENT PERSONNEL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCompensationOfKeyManagementPersonnel</Role>
      <ShortName>COMPENSATION OF KEY MANAGEMENT PERSONNEL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>12501 - Disclosure - COMMITMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCommitments</Role>
      <ShortName>COMMITMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>20202 - Disclosure - BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPoliciesPolicies</Role>
      <ShortName>BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>30203 - Disclosure - BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPoliciesTables</Role>
      <ShortName>BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPolicies</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>30503 - Disclosure - EXPENSES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureExpensesTables</Role>
      <ShortName>EXPENSES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>30603 - Disclosure - TRADE AND OTHER RECEIVABLES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherReceivablesTables</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureTradeAndOtherReceivables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>30703 - Disclosure - TRADE AND OTHER PAYABLES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherPayablesTables</Role>
      <ShortName>TRADE AND OTHER PAYABLES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureTradeAndOtherPayables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>30803 - Disclosure - INVENTORIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureInventoriesTables</Role>
      <ShortName>INVENTORIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureInventories</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>30903 - Disclosure - MINING INTERESTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureMiningInterestsTables</Role>
      <ShortName>MINING INTERESTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureMiningInterests</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>31003 - Disclosure - IMPAIRMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureImpairmentTables</Role>
      <ShortName>IMPAIRMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureImpairment</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>31103 - Disclosure - LONG-TERM DEBT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtTables</Role>
      <ShortName>LONG-TERM DEBT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureLongTermDebt</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>31203 - Disclosure - GOLD STREAM OBLIGATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureGoldStreamObligationTables</Role>
      <ShortName>GOLD STREAM OBLIGATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureGoldStreamObligation</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>31303 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLeasesTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureLeases</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>31403 - Disclosure - DERIVATIVE INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsTables</Role>
      <ShortName>DERIVATIVE INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureDerivativeInstruments</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>31503 - Disclosure - SHARE CAPITAL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalTables</Role>
      <ShortName>SHARE CAPITAL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureShareCapital</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>31603 - Disclosure - DISCONTINUED OPERATIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDiscontinuedOperationsTables</Role>
      <ShortName>DISCONTINUED OPERATIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureDiscontinuedOperations</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>31703 - Disclosure - INCOME AND MINING TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesTables</Role>
      <ShortName>INCOME AND MINING TAXES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxes</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>31803 - Disclosure - RECLAMATION AND CLOSURE COST OBLIGATIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligationsTables</Role>
      <ShortName>RECLAMATION AND CLOSURE COST OBLIGATIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligations</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>31903 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSupplementalCashFlowInformationTables</Role>
      <ShortName>SUPPLEMENTAL CASH FLOW INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureSupplementalCashFlowInformation</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>32003 - Disclosure - SEGMENTED INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationTables</Role>
      <ShortName>SEGMENTED INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureSegmentedInformation</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>32103 - Disclosure - CAPITAL RISK MANAGEMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCapitalRiskManagementTables</Role>
      <ShortName>CAPITAL RISK MANAGEMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureCapitalRiskManagement</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>32203 - Disclosure - FINANCIAL RISK MANAGEMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementTables</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureFinancialRiskManagement</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>32303 - Disclosure - FAIR VALUE MEASUREMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFairValueMeasurementTables</Role>
      <ShortName>FAIR VALUE MEASUREMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureFairValueMeasurement</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>32403 - Disclosure - COMPENSATION OF KEY MANAGEMENT PERSONNEL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCompensationOfKeyManagementPersonnelTables</Role>
      <ShortName>COMPENSATION OF KEY MANAGEMENT PERSONNEL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureCompensationOfKeyManagementPersonnel</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40201 - Disclosure - BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPoliciesDetails</Role>
      <ShortName>BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPoliciesTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>40202 - Disclosure - BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureBasisOfPreparationAndSignificantAccountingPoliciesAdditionalInformationDetails</Role>
      <ShortName>BASIS OF PREPARATION AND SIGNIFICANT ACCOUNTING POLICIES - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>40401 - Disclosure - REVISIONS TO PRIOR PERIOD COMPARATIVES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureRevisionsToPriorPeriodComparativesDetails</Role>
      <ShortName>REVISIONS TO PRIOR PERIOD COMPARATIVES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureRevisionsToPriorPeriodComparatives</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>40501 - Disclosure - EXPENSES - Operating expenses by nature (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureExpensesOperatingExpensesByNatureDetails</Role>
      <ShortName>EXPENSES - Operating expenses by nature (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>40502 - Disclosure - EXPENSES - Finance costs and income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureExpensesFinanceCostsAndIncomeDetails</Role>
      <ShortName>EXPENSES - Finance costs and income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>40503 - Disclosure - EXPENSES - Other (losses) and gains (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureExpensesOtherLossesAndGainsDetails</Role>
      <ShortName>EXPENSES - Other (losses) and gains (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>40601 - Disclosure - TRADE AND OTHER RECEIVABLES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherReceivablesDetails</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureTradeAndOtherReceivablesTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>40701 - Disclosure - TRADE AND OTHER PAYABLES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureTradeAndOtherPayablesDetails</Role>
      <ShortName>TRADE AND OTHER PAYABLES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureTradeAndOtherPayablesTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>40801 - Disclosure - INVENTORIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>INVENTORIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureInventoriesTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>40802 - Disclosure - INVENTORIES - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureInventoriesAdditionalInformationDetails</Role>
      <ShortName>INVENTORIES - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>40901 - Disclosure - MINING INTERESTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureMiningInterestsDetails</Role>
      <ShortName>MINING INTERESTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureMiningInterestsTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>40902 - Disclosure - MINING INTERESTS - Carrying amount (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureMiningInterestsCarryingAmountDetails</Role>
      <ShortName>MINING INTERESTS - Carrying amount (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>40903 - Disclosure - MINING INTERESTS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureMiningInterestsAdditionalInformationDetails</Role>
      <ShortName>MINING INTERESTS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>41001 - Disclosure - IMPAIRMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureImpairmentDetails</Role>
      <ShortName>IMPAIRMENT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureImpairmentTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>41002 - Disclosure - IMPAIRMENT - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureImpairmentAdditionalInformationDetails</Role>
      <ShortName>IMPAIRMENT - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>41101 - Disclosure - LONG-TERM DEBT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtDetails</Role>
      <ShortName>LONG-TERM DEBT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureLongTermDebtTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>41102 - Disclosure - LONG-TERM DEBT (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtParentheticalDetails</Role>
      <ShortName>LONG-TERM DEBT (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureLongTermDebtTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>41103 - Disclosure - LONG-TERM DEBT - Redemption prices (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtRedemptionPricesDetails</Role>
      <ShortName>LONG-TERM DEBT - Redemption prices (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>41104 - Disclosure - LONG-TERM DEBT - Borrowings redemption prices (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtBorrowingsRedemptionPricesDetails</Role>
      <ShortName>LONG-TERM DEBT - Borrowings redemption prices (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>41105 - Disclosure - LONG-TERM DEBT - Credit Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtCreditFacilityDetails</Role>
      <ShortName>LONG-TERM DEBT - Credit Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>41106 - Disclosure - LONG-TERM DEBT - Financial Covenants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtFinancialCovenantsDetails</Role>
      <ShortName>LONG-TERM DEBT - Financial Covenants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>41107 - Disclosure - LONG-TERM DEBT - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLongTermDebtAdditionalInformationDetails</Role>
      <ShortName>LONG-TERM DEBT - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>41201 - Disclosure - GOLD STREAM OBLIGATION - Change in stream obligation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureGoldStreamObligationChangeInStreamObligationDetails</Role>
      <ShortName>GOLD STREAM OBLIGATION - Change in stream obligation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>41202 - Disclosure - GOLD STREAM OBLIGATION - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureGoldStreamObligationAdditionalInformationDetails</Role>
      <ShortName>GOLD STREAM OBLIGATION - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>41301 - Disclosure - LEASES - Right-of-use assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLeasesRightOfUseAssetsDetails</Role>
      <ShortName>LEASES - Right-of-use assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>41302 - Disclosure - LEASES - Lease liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLeasesLeaseLiabilitiesDetails</Role>
      <ShortName>LEASES - Lease liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>41303 - Disclosure - LEASES - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureLeasesAdditionalInformationDetails</Role>
      <ShortName>LEASES - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>41401 - Disclosure - DERIVATIVE INSTRUMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureDerivativeInstrumentsTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>41402 - Disclosure - DERIVATIVE INSTRUMENTS - Provisionally priced sales (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsProvisionallyPricedSalesDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS - Provisionally priced sales (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>41403 - Disclosure - DERIVATIVE INSTRUMENTS - Swap contracts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsSwapContractsDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS - Swap contracts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>41404 - Disclosure - DERIVATIVE INSTRUMENTS - Impact of movements in market commodity prices (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsImpactOfMovementsInMarketCommodityPricesDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS - Impact of movements in market commodity prices (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>41405 - Disclosure - DERIVATIVE INSTRUMENTS - Gold price option contracts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsGoldPriceOptionContractsDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS - Gold price option contracts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>41406 - Disclosure - DERIVATIVE INSTRUMENTS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDerivativeInstrumentsAdditionalInformationDetails</Role>
      <ShortName>DERIVATIVE INSTRUMENTS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>41501 - Disclosure - SHARE CAPITAL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalDetails</Role>
      <ShortName>SHARE CAPITAL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureShareCapitalTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>41502 - Disclosure - SHARE CAPITAL - Share-based payment expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalShareBasedPaymentExpensesDetails</Role>
      <ShortName>SHARE CAPITAL - Share-based payment expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>41503 - Disclosure - SHARE CAPITAL - Stock options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalStockOptionsDetails</Role>
      <ShortName>SHARE CAPITAL - Stock options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>41504 - Disclosure - SHARE CAPITAL - Loss per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalLossPerShareDetails</Role>
      <ShortName>SHARE CAPITAL - Loss per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>41505 - Disclosure - SHARE CAPITAL - Stock options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalStockOptionsDetailss</Role>
      <ShortName>SHARE CAPITAL - Stock options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>41506 - Disclosure - SHARE CAPITAL - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureShareCapitalAdditionalInformationDetails</Role>
      <ShortName>SHARE CAPITAL - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>41601 - Disclosure - DISCONTINUED OPERATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDiscontinuedOperationsDetails</Role>
      <ShortName>DISCONTINUED OPERATIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureDiscontinuedOperationsTables</ParentRole>
      <Position>93</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>41602 - Disclosure - DISCONTINUED OPERATIONS - Mesquite (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDiscontinuedOperationsMesquiteDetails</Role>
      <ShortName>DISCONTINUED OPERATIONS - Mesquite (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>41603 - Disclosure - DISCONTINUED OPERATIONS - Cashflows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureDiscontinuedOperationsCashflowsDetails</Role>
      <ShortName>DISCONTINUED OPERATIONS - Cashflows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>41701 - Disclosure - INCOME AND MINING TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesDetails</Role>
      <ShortName>INCOME AND MINING TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesTables</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>41702 - Disclosure - INCOME AND MINING TAXES - Income tax recovery (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesIncomeTaxRecoveryDetails</Role>
      <ShortName>INCOME AND MINING TAXES - Income tax recovery (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>41703 - Disclosure - INCOME AND MINING TAXES - Deferred income tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesDeferredIncomeTaxDetails</Role>
      <ShortName>INCOME AND MINING TAXES - Deferred income tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>41704 - Disclosure - INCOME AND MINING TAXES - Movement in the net deferred tax liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesMovementInNetDeferredTaxLiabilitiesDetails</Role>
      <ShortName>INCOME AND MINING TAXES - Movement in the net deferred tax liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>41705 - Disclosure - INCOME AND MINING TAXES - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureIncomeAndMiningTaxesAdditionalInformationDetails</Role>
      <ShortName>INCOME AND MINING TAXES - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>41801 - Disclosure - RECLAMATION AND CLOSURE COST OBLIGATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligationsDetails</Role>
      <ShortName>RECLAMATION AND CLOSURE COST OBLIGATIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligationsTables</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>41802 - Disclosure - RECLAMATION AND CLOSURE COST OBLIGATIONS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureReclamationAndClosureCostObligationsAdditionalInformationDetails</Role>
      <ShortName>RECLAMATION AND CLOSURE COST OBLIGATIONS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>41901 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSupplementalCashFlowInformationDetails</Role>
      <ShortName>SUPPLEMENTAL CASH FLOW INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureSupplementalCashFlowInformationTables</ParentRole>
      <Position>103</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>42001 - Disclosure - SEGMENTED INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationDetails</Role>
      <ShortName>SEGMENTED INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureSegmentedInformationTables</ParentRole>
      <Position>104</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>42002 - Disclosure - SEGMENTED INFORMATION - Segmented assets and liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationSegmentedAssetsAndLiabilitiesDetails</Role>
      <ShortName>SEGMENTED INFORMATION - Segmented assets and liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>42003 - Disclosure - SEGMENTED INFORMATION - Information about major customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationInformationAboutMajorCustomersDetails</Role>
      <ShortName>SEGMENTED INFORMATION - Information about major customers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>42004 - Disclosure - SEGMENTED INFORMATION - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationAdditionalInformationDetails</Role>
      <ShortName>SEGMENTED INFORMATION - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>42101 - Disclosure - CAPITAL RISK MANAGEMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCapitalRiskManagementDetails</Role>
      <ShortName>CAPITAL RISK MANAGEMENT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureCapitalRiskManagementTables</ParentRole>
      <Position>108</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>42201 - Disclosure - FINANCIAL RISK MANAGEMENT - Credit risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementCreditRiskDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Credit risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>42202 - Disclosure - FINANCIAL RISK MANAGEMENT - Credit risk - Aging of trade and other receivables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementCreditRiskAgingOfTradeAndOtherReceivablesDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Credit risk - Aging of trade and other receivables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>42203 - Disclosure - FINANCIAL RISK MANAGEMENT - Liquidity risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementLiquidityRiskDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Liquidity risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>42204 - Disclosure - FINANCIAL RISK MANAGEMENT- Exposure to currency risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementExposureToCurrencyRiskDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT- Exposure to currency risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>42205 - Disclosure - FINANCIAL RISK MANAGEMENT - Translation exposure (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementTranslationExposureDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Translation exposure (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>42206 - Disclosure - FINANCIAL RISK MANAGEMENT - Metal and input price risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementMetalAndInputPriceRiskDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Metal and input price risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>42207 - Disclosure - FINANCIAL RISK MANAGEMENT - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFinancialRiskManagementAdditionalInformationDetails</Role>
      <ShortName>FINANCIAL RISK MANAGEMENT - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>42301 - Disclosure - FAIR VALUE MEASUREMENT - Summary of financial assets and liabilities by category (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFairValueMeasurementSummaryOfFinancialAssetsAndLiabilitiesByCategoryDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Summary of financial assets and liabilities by category (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>42302 - Disclosure - FAIR VALUE MEASUREMENT - Summary of carrying values and fair values of financial instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureFairValueMeasurementSummaryOfCarryingValuesAndFairValuesOfFinancialInstrumentsDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENT - Summary of carrying values and fair values of financial instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>42401 - Disclosure - COMPENSATION OF KEY MANAGEMENT PERSONNEL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCompensationOfKeyManagementPersonnelDetails</Role>
      <ShortName>COMPENSATION OF KEY MANAGEMENT PERSONNEL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureCompensationOfKeyManagementPersonnelTables</ParentRole>
      <Position>118</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>42501 - Disclosure - COMMITMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureCommitmentsDetails</Role>
      <ShortName>COMMITMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.newgold.com/role/DisclosureCommitments</ParentRole>
      <Position>119</Position>
    </Report>
    <Report instance="ngd-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>9442003 - Disclosure - SEGMENTED INFORMATION - Geographical information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.newgold.com/role/DisclosureSegmentedInformationGeographicalInformationDetails</Role>
      <ShortName>SEGMENTED INFORMATION - Geographical information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ngd-20191231.xml</File>
    <File>ngd-20191231.xsd</File>
    <File>ngd-20191231_cal.xml</File>
    <File>ngd-20191231_def.xml</File>
    <File>ngd-20191231_lab.xml</File>
    <File>ngd-20191231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/currency/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.ifrs.org/taxonomy/2019-03-27/ifrs-full</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
