<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>441</ContextCount>
  <ElementCount>381</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>68</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100030 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100040 - Statement - Consolidated Statements of Income (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/StatementConsolidatedStatementsOfIncomeUnaudited</Role>
      <ShortName>Consolidated Statements of Income (unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100050 - Statement - Consolidated Statements of Comprehensive Income (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeUnaudited</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100060 - Statement - Statements of Changes in Shareholders' Equity (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/StatementStatementsOfChangesInShareholdersEquityUnaudited1</Role>
      <ShortName>Statements of Changes in Shareholders' Equity (unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100070 - Statement - Statements of Changes in Shareholders' Equity (unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/StatementStatementsOfChangesInShareholdersEquityUnauditedParenthetical</Role>
      <ShortName>Statements of Changes in Shareholders' Equity (unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100080 - Statement - Consolidated Statements of Cash Flows (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>Consolidated Statements of Cash Flows (unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.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>9</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.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>10</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Conversion</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureConversion</Role>
      <ShortName>Conversion</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureBasisOfPresentation1</Role>
      <ShortName>Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Investments in Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecurities</Role>
      <ShortName>Investments in Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQuality</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Employee Benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureEmployeeBenefits</Role>
      <ShortName>Employee Benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Stock-based compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensation</Role>
      <ShortName>Stock-based compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Other Comprehensive (Loss) Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncome1</Role>
      <ShortName>Other Comprehensive (Loss) Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995545 - Disclosure - Regulatory Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureRegulatoryMatters</Role>
      <ShortName>Regulatory Matters</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Earnings per Share ("EPS")</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEps1</Role>
      <ShortName>Earnings per Share ("EPS")</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Derivative and Hedging Activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativeAndHedgingActivities</Role>
      <ShortName>Derivative and Hedging Activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Basis of Presentation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureBasisOfPresentationPolicies</Role>
      <ShortName>Basis of Presentation (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Investments in Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecuritiesTables</Role>
      <ShortName>Investments in Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecurities</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityTables</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQuality</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Employee Benefits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEmployeeBenefitsTables</Role>
      <ShortName>Employee Benefits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureEmployeeBenefits</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Stock-based compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationTables</Role>
      <ShortName>Stock-based compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurements</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Other Comprehensive (Loss) Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncomeTables</Role>
      <ShortName>Other Comprehensive (Loss) Income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncome1</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Regulatory Matters (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureRegulatoryMattersTables</Role>
      <ShortName>Regulatory Matters (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureRegulatoryMatters</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Earnings per Share ("EPS") (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEpsTables</Role>
      <ShortName>Earnings per Share ("EPS") (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEps1</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Derivatives and Hedging Activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativesAndHedgingActivitiesTables</Role>
      <ShortName>Derivatives and Hedging Activities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Conversion - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureConversionAdditionalInformationDetails</Role>
      <ShortName>Conversion - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Investments in Securities - Schedule of Held-to-Maturity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecuritiesScheduleOfHeldToMaturitySecuritiesDetails</Role>
      <ShortName>Investments in Securities - Schedule of Held-to-Maturity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Investments in Securities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecuritiesAdditionalInformationDetails</Role>
      <ShortName>Investments in Securities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Investments in Securities - Schedule of Available-for-Sale Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureInvestmentsInSecuritiesScheduleOfAvailableForSaleSecuritiesDetails</Role>
      <ShortName>Investments in Securities - Schedule of Available-for-Sale Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Investments in Securities - Schedule of Aggregate Fair Value and Unrealized Losses of Available-for-Sale Securities in a Continuous Unrealized Loss Position (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureInvestmentsInSecuritiesScheduleOfAggregateFairValueAndUnrealizedLossesOfAvailableforsaleSecuritiesInAContinuousUnrealizedLossPos</Role>
      <ShortName>Investments in Securities - Schedule of Aggregate Fair Value and Unrealized Losses of Available-for-Sale Securities in a Continuous Unrealized Loss Position (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Investments in Securities - Schedule of the Contractual Maturities of Available for Sale and Held-to-Maturity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureInvestmentsInSecuritiesScheduleOfTheContractualMaturitiesOfAvailableForSaleAndHeldtomaturitySecuritiesDetails</Role>
      <ShortName>Investments in Securities - Schedule of the Contractual Maturities of Available for Sale and Held-to-Maturity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Schedule of Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityScheduleOfLoansDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Schedule of Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityAdditionalInformationDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Allowance for Loan Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityScheduleOfInformationRegardingAllowanceForLoanLossesDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Allowance for Loan Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Allowance for Loan Losses (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityScheduleOfInformationRegardingAllowanceForLoanLossesParentheticalDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Allowance for Loan Losses (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Past Due Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityScheduleOfInformationRegardingPastDueLoansDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Past Due Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Nonaccrual Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualityScheduleOfInformationRegardingNonaccrualLoansDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Schedule of Information Regarding Nonaccrual Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Summary of Loans by Risk Rating (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualitySummaryOfLoansByRiskRatingDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Summary of Loans by Risk Rating (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Loans, Allowance for Credit Losses and Credit Quality - Summary of Loans by Risk Rating (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureLoansAllowanceForCreditLossesAndCreditQualitySummaryOfLoansByRiskRatingParentheticalDetails</Role>
      <ShortName>Loans, Allowance for Credit Losses and Credit Quality - Summary of Loans by Risk Rating (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995845 - Disclosure - Employee Benefits - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureEmployeeBenefitsAdditionalInformationDetails</Role>
      <ShortName>Employee Benefits - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995855 - Disclosure - Employee Benefits - Summary of Share information held by the ESOP (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEmployeeBenefitsSummaryOfShareInformationHeldByTheEsopDetails</Role>
      <ShortName>Employee Benefits - Summary of Share information held by the ESOP (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Stock-based compensation - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationAdditionalInformationDetails</Role>
      <ShortName>Stock-based compensation - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995875 - Disclosure - Stock-Based Compensation - Summary of Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationSummaryOfOptionActivityDetails</Role>
      <ShortName>Stock-Based Compensation - Summary of Option Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995885 - Disclosure - Stock-Based Compensation - Summary of Restricted Stock Award Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationSummaryOfRestrictedStockAwardActivityDetails</Role>
      <ShortName>Stock-Based Compensation - Summary of Restricted Stock Award Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Stock-Based Compensation - Summary of Compensation Expense and Income Tax Benefit Recognized (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompensationExpenseAndIncomeTaxBenefitRecognizedDetails</Role>
      <ShortName>Stock-Based Compensation - Summary of Compensation Expense and Income Tax Benefit Recognized (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995905 - Disclosure - Stock-Based Compensation - Schedule of Compensation Cost Related to Non-vested Awards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureStockbasedCompensationScheduleOfCompensationCostRelatedToNonvestedAwardsDetails</Role>
      <ShortName>Stock-Based Compensation - Schedule of Compensation Cost Related to Non-vested Awards (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995915 - Disclosure - Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurementsSummaryOfAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Fair Value Measurements - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurementsAdditionalInformationDetails</Role>
      <ShortName>Fair Value Measurements - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Fair Value Measurements - Summary of Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis or Non-Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureFairValueMeasurementsSummaryOfFinancialAssetsAndFinancialLiabilitiesMeasuredAtFairValueOnRecurringBasisOrNonrecurringBasisDetai</Role>
      <ShortName>Fair Value Measurements - Summary of Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis or Non-Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Commitments and Contingencies - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetails</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>995955 - Disclosure - Commitments and Contingencies - Summary of Financial Instrument Liabilities Represent Off-Balance Sheet Credit Risk (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesSummaryOfFinancialInstrumentLiabilitiesRepresentOffBalanceSheetCreditRiskDetail</Role>
      <ShortName>Commitments and Contingencies - Summary of Financial Instrument Liabilities Represent Off-Balance Sheet Credit Risk (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>995965 - Disclosure - Other Comprehensive (Loss) Income - Schedule of Components of Other Comprehensive (Loss) Income and Related Tax Effects (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncomeScheduleOfComponentsOfOtherComprehensiveLossIncomeAndRelatedTaxEffectsDetails</Role>
      <ShortName>Other Comprehensive (Loss) Income - Schedule of Components of Other Comprehensive (Loss) Income and Related Tax Effects (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncomeTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>995975 - Disclosure - Other Comprehensive (Loss) Income - Schedule of Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncomeScheduleOfAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Other Comprehensive (Loss) Income - Schedule of Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureOtherComprehensiveLossIncomeTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>995985 - Disclosure - Regulatory Matters - Schedule of Company's and Bank's Actual Capital Amounts and Ratios (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureRegulatoryMattersScheduleOfCompanysAndBanksActualCapitalAmountsAndRatiosDetails</Role>
      <ShortName>Regulatory Matters - Schedule of Company's and Bank's Actual Capital Amounts and Ratios (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>995995 - Disclosure - Earnings per Share ("EPS") - Schedule of Earnings per share data (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEpsScheduleOfEarningsPerShareDataDetails</Role>
      <ShortName>Earnings per Share ("EPS") - Schedule of Earnings per share data (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEpsTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Earnings per Share ("EPS") - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEpsAdditionalInformationDetails</Role>
      <ShortName>Earnings per Share ("EPS") - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://everettbank.com/20240930/taxonomy/role/DisclosureEarningsPerShareEpsTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Derivatives and Hedging Activities - Schedule of Interest Rate swaps (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativesAndHedgingActivitiesScheduleOfInterestRateSwapsDetails</Role>
      <ShortName>Derivatives and Hedging Activities - Schedule of Interest Rate swaps (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>996025 - Disclosure - Derivative and hedging activities - Schedule of Fair Value of Derivative Financial Instruments and Classification on Consolidated Balance Sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativeAndHedgingActivitiesScheduleOfFairValueOfDerivativeFinancialInstrumentsAndClassificationOnConsolidatedBalanceSheetsDeta</Role>
      <ShortName>Derivative and hedging activities - Schedule of Fair Value of Derivative Financial Instruments and Classification on Consolidated Balance Sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>996035 - Disclosure - Derivative and hedging activities - Schedule of pre-tax effects of cash flow hedge accumulated other comprehensive income and current earnings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativeAndHedgingActivitiesScheduleOfPretaxEffectsOfCashFlowHedgeAccumulatedOtherComprehensiveIncomeAndCurrentEarningsDetails</Role>
      <ShortName>Derivative and hedging activities - Schedule of pre-tax effects of cash flow hedge accumulated other comprehensive income and current earnings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="ecbk-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>996045 - Disclosure - Derivative and hedging activities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://everettbank.com/20240930/taxonomy/role/DisclosureDerivativeAndHedgingActivitiesAdditionalInformationDetails</Role>
      <ShortName>Derivative and hedging activities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</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="ecbk-20240930.htm">ecbk-20240930.htm</File>
    <File>ecbk-20240930.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="2195">http://fasb.org/us-gaap/2024</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2024</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2024</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
