<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>689</ContextCount>
  <ElementCount>371</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>124</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Consolidated Statements Of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements Of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Consolidated Statements of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfComprehensiveIncomeLoss</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Consolidated Statements of Comprehensive Income (Loss) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfComprehensiveIncomeLossParenthetical</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Loss) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Statement - Consolidated Statements Of Changes In Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInShareholdersEquity</Role>
      <ShortName>Consolidated Statements Of Changes In Shareholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Statement - Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInShareholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Statement - Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements Of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - General</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureGeneral</Role>
      <ShortName>General</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Stock-Based Compensation Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlan</Role>
      <ShortName>Stock-Based Compensation Plan</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Earnings Per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureEarningsPerCommonShare</Role>
      <ShortName>Earnings Per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecurities</Role>
      <ShortName>Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Loans and Allowance for Loan Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLosses</Role>
      <ShortName>Loans and Allowance for Loan Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Restructurings for Borrowers Experiencing Financial Difficulty</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficulty</Role>
      <ShortName>Restructurings for Borrowers Experiencing Financial Difficulty</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDeposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Change in Accumulated Other Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLoss1</Role>
      <ShortName>Change in Accumulated Other Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Other Real Estate Owned</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureOtherRealEstateOwned</Role>
      <ShortName>Other Real Estate Owned</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Qualified Affordable Housing Project Investments (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureQualifiedAffordableHousingProjectInvestmentsNotes</Role>
      <ShortName>Qualified Affordable Housing Project Investments (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Recent Accounting Pronouncements and Other Authoritative Guidance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureRecentAccountingPronouncementsAndOtherAuthoritativeGuidance</Role>
      <ShortName>Recent Accounting Pronouncements and Other Authoritative Guidance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBorrowings</Role>
      <ShortName>Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Derivatives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDerivatives</Role>
      <ShortName>Derivatives</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Business Segments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegments</Role>
      <ShortName>Business Segments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Employee Stock Ownership Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureEmployeeStockOwnershipPlan</Role>
      <ShortName>Employee Stock Ownership Plan</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Stock-Based Compensation Plan (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlanTables</Role>
      <ShortName>Stock-Based Compensation Plan (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlan</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Earnings Per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureEarningsPerCommonShareTables</Role>
      <ShortName>Earnings Per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureEarningsPerCommonShare</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecurities</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Loans and Allowance for Loan Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</Role>
      <ShortName>Loans and Allowance for Loan Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLosses</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Restructurings for Borrowers Experiencing Financial Difficulty (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyTables</Role>
      <ShortName>Restructurings for Borrowers Experiencing Financial Difficulty (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficulty</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDeposits</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLeases</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurements</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Change in Accumulated Other Comprehensive Income (Loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLossTables</Role>
      <ShortName>Change in Accumulated Other Comprehensive Income (Loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLoss1</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Other Real Estate Owned (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureOtherRealEstateOwnedTables</Role>
      <ShortName>Other Real Estate Owned (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureOtherRealEstateOwned</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Derivatives (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDerivativesTables</Role>
      <ShortName>Derivatives (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDerivatives</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Business Segments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegmentsTables</Role>
      <ShortName>Business Segments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegments</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - General (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureGeneralAdditionalInformationDetails</Role>
      <ShortName>General (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureGeneral</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Stock-Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock-Based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlanTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Stock-Based Compensation Plan (Restricted Stock Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlanRestrictedStockActivityDetails</Role>
      <ShortName>Stock-Based Compensation Plan (Restricted Stock Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureStockBasedCompensationPlanTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Earnings Per Common Share (Weighted Average Number Of Shares Used In Computing Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureEarningsPerCommonShareWeightedAverageNumberOfSharesUsedInComputingEarningsPerShareDetails</Role>
      <ShortName>Earnings Per Common Share (Weighted Average Number Of Shares Used In Computing Earnings Per Share) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureEarningsPerCommonShareTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Securities - (Amortized Costs and Fair Values of Securities Available for Sale) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureSecuritiesAmortizedCostsAndFairValuesOfSecuritiesAvailableForSaleDetails</Role>
      <ShortName>Securities - (Amortized Costs and Fair Values of Securities Available for Sale) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Securities - (Contractual Maturity of Securities Available for Sale) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureSecuritiesContractualMaturityOfSecuritiesAvailableForSaleDetails</Role>
      <ShortName>Securities - (Contractual Maturity of Securities Available for Sale) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Securities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesNarrativeDetails</Role>
      <ShortName>Securities (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Securities (Fair Value and Gross Unrealized Losses for Securities Available for Sale) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureSecuritiesFairValueAndGrossUnrealizedLossesForSecuritiesAvailableForSaleDetails</Role>
      <ShortName>Securities (Fair Value and Gross Unrealized Losses for Securities Available for Sale) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Securities (Restricted Investments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesRestrictedInvestmentsDetails</Role>
      <ShortName>Securities (Restricted Investments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureSecuritiesTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Loans and Allowance for Loan Losses (Schedule of Composition of Loans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesScheduleOfCompositionOfLoansDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Schedule of Composition of Loans) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Loans and Allowance for Loan Losses (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesNarrativeDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Loans and Allowance for Loan Losses (Changes In Allowance For Loan Losses) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesChangesInAllowanceForLoanLossesDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Changes In Allowance For Loan Losses) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Loans and Allowance for Loan Losses (Nonaccrual And Past Due Loans By Class) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesNonaccrualAndPastDueLoansByClassDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Nonaccrual And Past Due Loans By Class) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Loans and Allowance for Loan Losses (Allowance For Loan Losses By Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesAllowanceForLoanLossesBySegmentDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Allowance For Loan Losses By Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Loans and Allowance for Credit Losses on Loans - Amortized cost basis of collateral-dependent loans by loan portfolio segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansAmortizedCostBasisOfCollateraldependentLoansByLoanPortfolioSegmentDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses on Loans - Amortized cost basis of collateral-dependent loans by loan portfolio segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Loans and Allowance for Loan Losses (Credit Quality Information By Class) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesCreditQualityInformationByClassDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses (Credit Quality Information By Class) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLoansAndAllowanceForLoanLossesTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Restructurings for Borrowers Experiencing Financial Difficulty (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyNarrativeDetails</Role>
      <ShortName>Restructurings for Borrowers Experiencing Financial Difficulty (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Restructurings for Borrowers Experiencing Financial Difficulty (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyDetails</Role>
      <ShortName>Restructurings for Borrowers Experiencing Financial Difficulty (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Restructurings for Borrowers Experiencing Financial Difficulty (Schedule of Troubled Debt Restructurings on Financing Receivables) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyScheduleOfTroubledDebtRestructuringsOnFinancingReceivablesDetails</Role>
      <ShortName>Restructurings for Borrowers Experiencing Financial Difficulty (Schedule of Troubled Debt Restructurings on Financing Receivables) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRestructuringsForBorrowersExperiencingFinancialDifficultyTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Deposits (Composition Of Deposits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDepositsCompositionOfDepositsDetails</Role>
      <ShortName>Deposits (Composition Of Deposits) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDepositsTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Leases - Schedule of Lease Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLeasesScheduleOfLeaseInformationDetails</Role>
      <ShortName>Leases - Schedule of Lease Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Leases - Schedule of Maturity of Lease Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureLeasesScheduleOfMaturityOfLeaseLiabilityDetails</Role>
      <ShortName>Leases - Schedule of Maturity of Lease Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnARecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100640 - Disclosure - Fair Value Measurements (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsNarrativeDetails</Role>
      <ShortName>Fair Value Measurements (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>100650 - Disclosure - Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements For Certain Financial Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsQuantitativeInformationAboutLevel3FairValueMeasurementsForCertainFinancialAssetsDetails</Role>
      <ShortName>Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements For Certain Financial Assets) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>100660 - Disclosure - Fair Value Measurements (Financial And Nonfinancial Assets Measured At Fair Value On A Nonrecurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsFinancialAndNonfinancialAssetsMeasuredAtFairValueOnANonrecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements (Financial And Nonfinancial Assets Measured At Fair Value On A Nonrecurring Basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>100670 - Disclosure - Fair Value Measurements (Company's Financial Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsCompanySFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value Measurements (Company's Financial Instruments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>100680 - Disclosure - Change in Accumulated Other Comprehensive Income - (Loss) Changes To Accumulated Other Comprehensive Income By Components (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLossChangesToAccumulatedOtherComprehensiveIncomeByComponentsDetails</Role>
      <ShortName>Change in Accumulated Other Comprehensive Income - (Loss) Changes To Accumulated Other Comprehensive Income By Components (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>100690 - Disclosure - Change in Accumulated Other Comprehensive Income (Loss) (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureChangeInAccumulatedOtherComprehensiveIncomeLossNarrativeDetails</Role>
      <ShortName>Change in Accumulated Other Comprehensive Income (Loss) (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureChangeInAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>100700 - Disclosure - Other Real Estate Owned - Other Real Estate Owned Rollforward (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureOtherRealEstateOwnedOtherRealEstateOwnedRollforwardDetails</Role>
      <ShortName>Other Real Estate Owned - Other Real Estate Owned Rollforward (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>100710 - Disclosure - Other Real Estate Owned - Schedule of Real Estate Properties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureOtherRealEstateOwnedScheduleOfRealEstatePropertiesDetails</Role>
      <ShortName>Other Real Estate Owned - Schedule of Real Estate Properties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>100730 - Disclosure - Qualified Affordable Housing Project Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureQualifiedAffordableHousingProjectInvestmentsDetails</Role>
      <ShortName>Qualified Affordable Housing Project Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureQualifiedAffordableHousingProjectInvestmentsNotes</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>100740 - Disclosure - Recent Accounting Pronouncements and Other Authoritative Guidance (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureRecentAccountingPronouncementsAndOtherAuthoritativeGuidanceAdditionalInformationDetails</Role>
      <ShortName>Recent Accounting Pronouncements and Other Authoritative Guidance (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>100750 - Disclosure - Borrowings (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBorrowingsNarrativeDetails</Role>
      <ShortName>Borrowings (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBorrowings</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>100760 - Disclosure - Derivative (Summarize Key Elements of Derivative Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDerivativeSummarizeKeyElementsOfDerivativeInstrumentsDetails</Role>
      <ShortName>Derivative (Summarize Key Elements of Derivative Instruments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/Role_DisclosureDerivativesTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>100770 - Disclosure - Business Segments - Schedule of the wealth management division's revenue and expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegmentsScheduleOfTheWealthManagementDivisionsRevenueAndExpensesDetails</Role>
      <ShortName>Business Segments - Schedule of the wealth management division's revenue and expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>100780 - Disclosure - Business Segments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegmentsNarrativeDetails</Role>
      <ShortName>Business Segments (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureBusinessSegmentsTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="efsi-20230930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>100790 - Disclosure - Employee Stock Ownership Plan (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://bankofclarke.com/20230930/taxonomy/role/DisclosureEmployeeStockOwnershipPlanAdditionalInformationDetails</Role>
      <ShortName>Employee Stock Ownership Plan (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://bankofclarke.com/20230930/taxonomy/role/DisclosureEmployeeStockOwnershipPlan</ParentRole>
      <Position>76</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-Q" isDefinitelyFs="true" isUsgaap="true" original="efsi-20230930.htm">efsi-20230930.htm</File>
    <File>efsi-20230930.xsd</File>
    <File>efsi-20230930_cal.xml</File>
    <File>efsi-20230930_def.xml</File>
    <File>efsi-20230930_lab.xml</File>
    <File>efsi-20230930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="1904">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="26">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
