<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>421</ContextCount>
  <ElementCount>585</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>124</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>75000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>75010 - Statement - Consolidated Statements of Financial Condition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfFinancialCondition</Role>
      <ShortName>Consolidated Statements of Financial Condition</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>75020 - Statement - Consolidated Statements of Financial Condition (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfFinancialConditionParenthetical</Role>
      <ShortName>Consolidated Statements of Financial Condition (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>75030 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>75040 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>75050 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>75060 - Statement - Consolidated Statements of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>75070 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>75080 - Disclosure - Cybersecurity Risk Management, Strategy, and Governance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCybersecurityRiskManagementStrategyAndGovernance</Role>
      <ShortName>Cybersecurity Risk Management, Strategy, and Governance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.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>10</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.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>11</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Organization and Nature of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOrganizationAndNatureOfOperations</Role>
      <ShortName>Organization and Nature of Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Investment Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecurities</Role>
      <ShortName>Investment Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Loans Receivable</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivable</Role>
      <ShortName>Loans Receivable</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Allowance for Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLosses1</Role>
      <ShortName>Allowance for Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Premises and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipment</Role>
      <ShortName>Premises and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDeposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowings</Role>
      <ShortName>Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Lease Obligations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligations</Role>
      <ShortName>Lease Obligations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995545 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Employee and Director Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEmployeeAndDirectorBenefitPlans</Role>
      <ShortName>Employee and Director Benefit Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Stock-based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock-based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Regulatory Capital Requirements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirements</Role>
      <ShortName>Regulatory Capital Requirements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Earnings per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShare</Role>
      <ShortName>Earnings per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Commitments to Extend Credit</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCommitmentsToExtendCredit</Role>
      <ShortName>Commitments to Extend Credit</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Parent Company Only Financial Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformation</Role>
      <ShortName>Parent Company Only Financial Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Treasury Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureTreasuryStock</Role>
      <ShortName>Treasury Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Other Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLoss</Role>
      <ShortName>Other Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Revenue Recognition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRevenueRecognition</Role>
      <ShortName>Revenue Recognition</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Summary of Significant Accounting Policies (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicy</Role>
      <ShortName>Summary of Significant Accounting Policies (Policy)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Investment Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesTables</Role>
      <ShortName>Investment Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecurities</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Loans Receivable (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableTables</Role>
      <ShortName>Loans Receivable (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivable</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Allowance for Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</Role>
      <ShortName>Allowance for Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLosses1</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Premises and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipmentTables</Role>
      <ShortName>Premises and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipment</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDeposits</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowingsTables</Role>
      <ShortName>Borrowings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowings</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Lease Obligations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligationsTables</Role>
      <ShortName>Lease Obligations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligations</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxes</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Stock-based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock-based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensation</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstruments</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Regulatory Capital Requirements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirementsTables</Role>
      <ShortName>Regulatory Capital Requirements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirements</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Earnings per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShareTables</Role>
      <ShortName>Earnings per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShare</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Commitments to Extend Credit (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCommitmentsToExtendCreditTables</Role>
      <ShortName>Commitments to Extend Credit (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCommitmentsToExtendCredit</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Parent Company Only Financial Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationTables</Role>
      <ShortName>Parent Company Only Financial Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformation</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Other Comprehensive Income (Loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLossTables</Role>
      <ShortName>Other Comprehensive Income (Loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLoss</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Revenue Recognition (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRevenueRecognitionTables</Role>
      <ShortName>Revenue Recognition (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRevenueRecognition</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Organization and Nature of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOrganizationAndNatureOfOperationsDetails</Role>
      <ShortName>Organization and Nature of Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOrganizationAndNatureOfOperations</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995845 - Disclosure - Summary of Significant Accounting Policies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Summary of Significant Accounting Policies (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicy</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995855 - Disclosure - Investment Securities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails</Role>
      <ShortName>Investment Securities (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Investment Securities (Amortized Cost and Fair Value of Securities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfSecuritiesDetails</Role>
      <ShortName>Investment Securities (Amortized Cost and Fair Value of Securities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995875 - Disclosure - Investment Securities (Investment in Debt Securities Gross Unrealized Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesInvestmentInDebtSecuritiesGrossUnrealizedLossDetails</Role>
      <ShortName>Investment Securities (Investment in Debt Securities Gross Unrealized Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995885 - Disclosure - Investment Securities (Scheduled Contractual Maturities Debt Securities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesScheduledContractualMaturitiesDebtSecuritiesDetails</Role>
      <ShortName>Investment Securities (Scheduled Contractual Maturities Debt Securities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureInvestmentSecuritiesTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Loans Receivable (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableNarrativeDetails</Role>
      <ShortName>Loans Receivable (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995905 - Disclosure - Loans Receivable (Schedule of Loans Receivable, Net) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableScheduleOfLoansReceivableNetDetails</Role>
      <ShortName>Loans Receivable (Schedule of Loans Receivable, Net) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995915 - Disclosure - Loans Receivable (Schedule of Loans Receivable, Net) (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableScheduleOfLoansReceivableNetParentheticalDetails</Role>
      <ShortName>Loans Receivable (Schedule of Loans Receivable, Net) (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLoansReceivableTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Allowance for Credit Losses (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesNarrativeDetails</Role>
      <ShortName>Allowance for Credit Losses (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Allowance for Credit Losses (Summary of Activity in Allowance for Credit Losses) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesSummaryOfActivityInAllowanceForCreditLossesDetails</Role>
      <ShortName>Allowance for Credit Losses (Summary of Activity in Allowance for Credit Losses) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Allowance for Credit Losses - (Schedule of Activity in Allowance for Credit Losses on Unfunded Loan Commitments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfActivityInAllowanceForCreditLossesOnUnfundedLoanCommitmentsDetails</Role>
      <ShortName>Allowance for Credit Losses - (Schedule of Activity in Allowance for Credit Losses on Unfunded Loan Commitments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>995955 - Disclosure - Allowance for Credit Losses - (Schedule of Non Accrual by Loan Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfNonAccrualByLoanSegmentDetails</Role>
      <ShortName>Allowance for Credit Losses - (Schedule of Non Accrual by Loan Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>995965 - Disclosure - Allowance for Credit Losses (Analysis of Past Due Loans and Non-Accruing Loans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesAnalysisOfPastDueLoansAndNonaccruingLoansDetails</Role>
      <ShortName>Allowance for Credit Losses (Analysis of Past Due Loans and Non-Accruing Loans) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>995975 - Disclosure - Allowance for Credit Losses - (Schedule of Amortized Cost of Collateral-Dependent Loans by Loan Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAmortizedCostOfCollateraldependentLoansByLoanSegmentDetails</Role>
      <ShortName>Allowance for Credit Losses - (Schedule of Amortized Cost of Collateral-Dependent Loans by Loan Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForCreditLossesTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>995985 - Disclosure - Allowance for Loan Losses (Gross Loans by Credit Quality Indicator by Origination Year) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureAllowanceForLoanLossesGrossLoansByCreditQualityIndicatorByOriginationYearDetails</Role>
      <ShortName>Allowance for Loan Losses (Gross Loans by Credit Quality Indicator by Origination Year) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Premises and Equipment (Schedule of Premises and Equipment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipmentScheduleOfPremisesAndEquipmentDetails</Role>
      <ShortName>Premises and Equipment (Schedule of Premises and Equipment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipmentTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Premises and Equipment (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipmentNarrativeDetails</Role>
      <ShortName>Premises and Equipment (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosurePremisesAndEquipmentTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>996025 - Disclosure - Deposits Schedule of Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsScheduleOfDepositsDetails</Role>
      <ShortName>Deposits Schedule of Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>996035 - Disclosure - Deposits Schedule of Maturities of Time Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails</Role>
      <ShortName>Deposits Schedule of Maturities of Time Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>996045 - Disclosure - Deposits (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsNarrativeDetails</Role>
      <ShortName>Deposits (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>996055 - Disclosure - Deposits (Schedule of Interest Expense on Deposits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsScheduleOfInterestExpenseOnDepositsDetails</Role>
      <ShortName>Deposits (Schedule of Interest Expense on Deposits) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureDepositsTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>996065 - Disclosure - Borrowings (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowingsNarrativeDetails</Role>
      <ShortName>Borrowings (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowingsTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>996075 - Disclosure - Borrowings (Long-term Debt from FHLBNY and Related Contractual Maturities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowingsLongTermDebtFromFhlbnyAndRelatedContractualMaturitiesDetails</Role>
      <ShortName>Borrowings (Long-term Debt from FHLBNY and Related Contractual Maturities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureBorrowingsTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>996085 - Disclosure - Leases Obligations (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeasesObligationsNarrativeDetails</Role>
      <ShortName>Leases Obligations (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>996095 - Disclosure - Lease Obligations (Summary of Information Related to Leases Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligationsSummaryOfInformationRelatedToLeasesLiabilitiesDetails</Role>
      <ShortName>Lease Obligations (Summary of Information Related to Leases Liabilities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligationsTables</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>996105 - Disclosure - Lease Obligations (Summary of Maturity of Remaining Lease Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligationsSummaryOfMaturityOfRemainingLeaseLiabilitiesDetails</Role>
      <ShortName>Lease Obligations (Summary of Maturity of Remaining Lease Liabilities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureLeaseObligationsTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>996125 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>996135 - Disclosure - Income Taxes (Schedule of Provision for Income Tax Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesScheduleOfProvisionForIncomeTaxExpenseDetails</Role>
      <ShortName>Income Taxes (Schedule of Provision for Income Tax Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>996145 - Disclosure - Income Taxes (Schedule of Reconciliation of Statutory Federal Income Tax) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfStatutoryFederalIncomeTaxDetails</Role>
      <ShortName>Income Taxes (Schedule of Reconciliation of Statutory Federal Income Tax) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>996155 - Disclosure - Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails</Role>
      <ShortName>Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>996165 - Disclosure - Employee and Director Benefit Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEmployeeAndDirectorBenefitPlansDetails</Role>
      <ShortName>Employee and Director Benefit Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEmployeeAndDirectorBenefitPlans</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>996175 - Disclosure - Stock-based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock-based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>996185 - Disclosure - Stock-based Compensation (Summary of Status of Stock Option Plan) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStatusOfStockOptionPlanDetails</Role>
      <ShortName>Stock-based Compensation (Summary of Status of Stock Option Plan) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>996195 - Disclosure - Stock-based Compensation (Schedule of Unvested Restricted Stock Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfUnvestedRestrictedStockActivityDetails</Role>
      <ShortName>Stock-based Compensation (Schedule of Unvested Restricted Stock Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>996205 - Disclosure - Stock-based Compensation (Schedule of Awards Granted ) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAwardsGrantedDetails</Role>
      <ShortName>Stock-based Compensation (Schedule of Awards Granted ) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>996215 - Disclosure - Fair Value of Financial Instruments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsNarrativeDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>996225 - Disclosure - Fair Value of Financial Instruments (Fair Value of Assets Measured on Recurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsFairValueOfAssetsMeasuredOnRecurringBasisDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Fair Value of Assets Measured on Recurring Basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>86</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>996235 - Disclosure - Fair Value of Financial Instruments (Assets Measured at Fair Value on Nonrecurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAssetsMeasuredAtFairValueOnNonrecurringBasisDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Assets Measured at Fair Value on Nonrecurring Basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>996245 - Disclosure - Fair Value of Financial Instruments (Additional Quantitative Information About Assets Measured at Fair Value) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalQuantitativeInformationAboutAssetsMeasuredAtFairValueDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Additional Quantitative Information About Assets Measured at Fair Value) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>996255 - Disclosure - Fair Value of Financial Instruments (Carrying Amount and Estimated Fair Value of Financial Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsCarryingAmountAndEstimatedFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Carrying Amount and Estimated Fair Value of Financial Instruments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>996265 - Disclosure - Regulatory Capital Requirements (Narrative ) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirementsNarrativeDetails</Role>
      <ShortName>Regulatory Capital Requirements (Narrative ) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirementsTables</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>996275 - Disclosure - Regulatory Capital Requirements (Schedule of Actual and Required Capital Amounts and Ratios) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirementsScheduleOfActualAndRequiredCapitalAmountsAndRatiosDetails</Role>
      <ShortName>Regulatory Capital Requirements (Schedule of Actual and Required Capital Amounts and Ratios) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRegulatoryCapitalRequirementsTables</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>996285 - Disclosure - Earnings per Share (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShareNarrativeDetails</Role>
      <ShortName>Earnings per Share (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShareTables</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>996295 - Disclosure - Earnings per Share (Calculated Basic and Diluted Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShareCalculatedBasicAndDilutedEarningsPerShareDetails</Role>
      <ShortName>Earnings per Share (Calculated Basic and Diluted Earnings Per Share) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureEarningsPerShareTables</ParentRole>
      <Position>93</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>996305 - Disclosure - Commitments to Extend Credit (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCommitmentsToExtendCreditDetails</Role>
      <ShortName>Commitments to Extend Credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureCommitmentsToExtendCreditTables</ParentRole>
      <Position>94</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>996315 - Disclosure - Parent Company Only Financial Information (Statements of Financial Condition) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationStatementsOfFinancialConditionDetails</Role>
      <ShortName>Parent Company Only Financial Information (Statements of Financial Condition) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationTables</ParentRole>
      <Position>95</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>996325 - Disclosure - Parent Company Only Financial Information (Statements of Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationStatementsOfIncomeDetails</Role>
      <ShortName>Parent Company Only Financial Information (Statements of Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationTables</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>996335 - Disclosure - Parent Company Only Financial Information (Statements of Cash Flows) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationStatementsOfCashFlowsDetails</Role>
      <ShortName>Parent Company Only Financial Information (Statements of Cash Flows) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureParentCompanyOnlyFinancialInformationTables</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>996345 - Disclosure - Treasury Stock and Repurchases to Authorized and Unissued (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureTreasuryStockAndRepurchasesToAuthorizedAndUnissuedDetails</Role>
      <ShortName>Treasury Stock and Repurchases to Authorized and Unissued (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>996355 - Disclosure - Other Comprehensive Income (Loss) (Tax Effects Allocated to Single Component of Other Comprehensive Income (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLossTaxEffectsAllocatedToSingleComponentOfOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Other Comprehensive Income (Loss) (Tax Effects Allocated to Single Component of Other Comprehensive Income (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>996365 - Disclosure - Other Comprehensive Income (Loss) (Reclassification Out of Accumulated Other Comprehensive Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLossReclassificationOutOfAccumulatedOtherComprehensiveLossDetails</Role>
      <ShortName>Other Comprehensive Income (Loss) (Reclassification Out of Accumulated Other Comprehensive Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>100</Position>
    </Report>
    <Report instance="lsbk-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>996385 - Disclosure - Revenue Recognition (Non-Interest Income, Segregated by Revenue Streams In-Scope and Out-of-Scope of Topic 606) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRevenueRecognitionNonInterestIncomeSegregatedByRevenueStreamsInScopeAndOutOfScopeOfTopic606Details</Role>
      <ShortName>Revenue Recognition (Non-Interest Income, Segregated by Revenue Streams In-Scope and Out-of-Scope of Topic 606) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.mylsbank.com/20251231/taxonomy/role/DisclosureRevenueRecognitionTables</ParentRole>
      <Position>101</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="lsbk-20251231.htm">lsbk-20251231.htm</File>
    <File>lsbk-20251231.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="3">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="1631">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="13">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="40">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
