<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>396</ContextCount>
  <ElementCount>328</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>115</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>995200090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>995200100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>995200105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>995200200 - Statement - CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>995200300 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>995200400 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedStatementsOfChangesInPartnersCapital</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>995200500 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995210101 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSignificantAccountingPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995210201 - Disclosure - RENTAL PROPERTIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalProperties</Role>
      <ShortName>RENTAL PROPERTIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995210301 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995210401 - Disclosure - PREPAID EXPENSES and OTHER ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosurePrepaidExpensesAndOtherAssets</Role>
      <ShortName>PREPAID EXPENSES and OTHER ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995210501 - Disclosure - MORTGAGE NOTES PAYABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureMortgageNotesPayable</Role>
      <ShortName>MORTGAGE NOTES PAYABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995210601 - Disclosure - ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureAdvanceRentalPaymentsAndSecurityDeposits</Role>
      <ShortName>ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995210701 - Disclosure - PARTNERS' CAPITAL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosurePartnersCapital</Role>
      <ShortName>PARTNERS' CAPITAL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995210801 - Disclosure - TREASURY UNITS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureTreasuryUnits</Role>
      <ShortName>TREASURY UNITS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995210901 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995211001 - Disclosure - RENTAL INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncome</Role>
      <ShortName>RENTAL INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995211101 - Disclosure - CASH FLOW INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureCashFlowInformation</Role>
      <ShortName>CASH FLOW INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995211201 - Disclosure - FAIR VALUE MEASUREMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureFairValueMeasurements</Role>
      <ShortName>FAIR VALUE MEASUREMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995211301 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstruments</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995211401 - Disclosure - TAXABLE INCOME AND TAX BASIS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureTaxableIncomeAndTaxBasis</Role>
      <ShortName>TAXABLE INCOME AND TAX BASIS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995211501 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVentures</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995211601 - Disclosure - EMPLOYEE BENEFIT 401(k) PLANS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureEmployeeBenefit401KPlans</Role>
      <ShortName>EMPLOYEE BENEFIT 401(k) PLANS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995211701 - Disclosure - IMPACT OF RECENTLY-ISSUED ACCOUNTING STANDARDS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureImpactOfRecentlyIssuedAccountingStandards</Role>
      <ShortName>IMPACT OF RECENTLY-ISSUED ACCOUNTING STANDARDS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995211801 - Disclosure - SEGMENT REPORTING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSegmentReporting</Role>
      <ShortName>SEGMENT REPORTING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995211901 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>99920102 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>99930203 - Disclosure - RENTAL PROPERTIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalPropertiesTables</Role>
      <ShortName>RENTAL PROPERTIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalProperties</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>99930503 - Disclosure - MORTGAGE NOTES PAYABLE (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureMortgageNotesPayableTables</Role>
      <ShortName>MORTGAGE NOTES PAYABLE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureMortgageNotesPayable</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>99930703 - Disclosure - PARTNERS' CAPITAL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosurePartnersCapitalTables</Role>
      <ShortName>PARTNERS' CAPITAL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosurePartnersCapital</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>99930803 - Disclosure - TREASURY UNITS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureTreasuryUnitsTables</Role>
      <ShortName>TREASURY UNITS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureTreasuryUnits</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>99931003 - Disclosure - RENTAL INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeTables</Role>
      <ShortName>RENTAL INCOME (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalIncome</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>99931203 - Disclosure - FAIR VALUE MEASUREMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>FAIR VALUE MEASUREMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureFairValueMeasurements</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>99931303 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstrumentsTables</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstruments</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>99931503 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVentures</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>99940101 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Business (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSignificantAccountingPoliciesBusinessDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Business (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>99940102 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSignificantAccountingPoliciesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>99940201 - Disclosure - RENTAL PROPERTIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalPropertiesDetails</Role>
      <ShortName>RENTAL PROPERTIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalPropertiesTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>99940202 - Disclosure - RENTAL PROPERTIES - Belmont Acquisition (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalPropertiesBelmontAcquisitionDetails</Role>
      <ShortName>RENTAL PROPERTIES - Belmont Acquisition (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>99940203 - Disclosure - RENTAL PROPERTIES - Mill Street Development (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalPropertiesMillStreetDevelopmentDetails</Role>
      <ShortName>RENTAL PROPERTIES - Mill Street Development (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>99940301 - Disclosure - RELATED PARTY TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>RELATED PARTY TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRelatedPartyTransactions</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>99940401 - Disclosure - PREPAID EXPENSES and OTHER ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosurePrepaidExpensesAndOtherAssetsDetails</Role>
      <ShortName>PREPAID EXPENSES and OTHER ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosurePrepaidExpensesAndOtherAssets</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>99940501 - Disclosure - MORTGAGE NOTES PAYABLE - Mortgages Payable (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureMortgageNotesPayableMortgagesPayableDetails</Role>
      <ShortName>MORTGAGE NOTES PAYABLE - Mortgages Payable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>99940502 - Disclosure - MORTGAGE NOTES PAYABLE - Line of Credit (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureMortgageNotesPayableLineOfCreditDetails</Role>
      <ShortName>MORTGAGE NOTES PAYABLE - Line of Credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>99940601 - Disclosure - ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureAdvanceRentalPaymentsAndSecurityDepositsDetails</Role>
      <ShortName>ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureAdvanceRentalPaymentsAndSecurityDeposits</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>99940701 - Disclosure - PARTNERS' CAPITAL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosurePartnersCapitalDetails</Role>
      <ShortName>PARTNERS' CAPITAL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosurePartnersCapitalTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>99940801 - Disclosure - TREASURY UNITS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureTreasuryUnitsDetails</Role>
      <ShortName>TREASURY UNITS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureTreasuryUnitsTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>99941001 - Disclosure - RENTAL INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeDetails</Role>
      <ShortName>RENTAL INCOME (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>99941002 - Disclosure - RENTAL INCOME (Concentration) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeConcentrationDetails</Role>
      <ShortName>RENTAL INCOME (Concentration) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>99941003 - Disclosure - RENTAL INCOME (Commercial Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeCommercialLeasesDetails</Role>
      <ShortName>RENTAL INCOME (Commercial Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>99941004 - Disclosure - RENTAL INCOME (Rent Receivable) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeRentReceivableDetails</Role>
      <ShortName>RENTAL INCOME (Rent Receivable) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureRentalIncomeTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>99941101 - Disclosure - CASH FLOW INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureCashFlowInformationDetails</Role>
      <ShortName>CASH FLOW INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureCashFlowInformation</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>99941201 - Disclosure - FAIR VALUE MEASUREMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureFairValueMeasurementsDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>99941301 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstrumentsDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstrumentsTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>99941302 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Classification on the consolidated balance sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstrumentsClassificationOnConsolidatedBalanceSheetsDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Classification on the consolidated balance sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>99941303 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Effect on statements of income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureDerivativeFinancialInstrumentsEffectOnStatementsOfIncomeDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Effect on statements of income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>99941401 - Disclosure - TAXABLE INCOME AND TAX BASIS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureTaxableIncomeAndTaxBasisDetails</Role>
      <ShortName>TAXABLE INCOME AND TAX BASIS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureTaxableIncomeAndTaxBasis</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>99941501 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>99941502 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Dexter) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesDexterDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Dexter) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>99941503 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton Essex) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesHamiltonEssexDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton Essex) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>99941504 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton 1025) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesHamilton1025Details</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton 1025) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>99941505 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton Minuteman) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesHamiltonMinutemanDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton Minuteman) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>99941506 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton on Main) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesHamiltonOnMainDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Hamilton on Main) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>99941507 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (345 Franklin) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVentures345FranklinDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (345 Franklin) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>99941508 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Balance Sheet) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesBalanceSheetDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Balance Sheet) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>99941509 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesIncomeDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>99941510 - Disclosure - INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Mortgage Maturities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesMortgageMaturitiesDetails</Role>
      <ShortName>INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Mortgage Maturities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureInvestmentInUnconsolidatedJointVenturesTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>99941601 - Disclosure - EMPLOYEE BENEFIT 401(k) PLANS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureEmployeeBenefit401KPlansDetails</Role>
      <ShortName>EMPLOYEE BENEFIT 401(k) PLANS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureEmployeeBenefit401KPlans</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>99941801 - Disclosure - SEGMENT REPORTING (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSegmentReportingDetails</Role>
      <ShortName>SEGMENT REPORTING (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureSegmentReporting</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="nen-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>99941901 - Disclosure - SUBSEQUENT EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehamiltoncompany.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>SUBSEQUENT EVENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehamiltoncompany.com/role/DisclosureSubsequentEvents</ParentRole>
      <Position>72</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>nen-20260630.xsd</File>
    <File>nen-20260630_cal.xml</File>
    <File>nen-20260630_def.xml</File>
    <File>nen-20260630_lab.xml</File>
    <File>nen-20260630_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="nen-20260630x10q.htm">nen-20260630x10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="1230">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="35">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
