3.26.1 html 87 80 1 false 16 0 false 3 false false R1.htm 00090 - Document - Document and Entity Information Sheet http://metropolitanbankny.com/role/DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 00100 - Statement - Statements of Net Assets Available for Benefits Sheet http://metropolitanbankny.com/role/StatementStatementsOfNetAssetsAvailableForBenefits Statements of Net Assets Available for Benefits Statements 2 false false R3.htm 00200 - Statement - Statement of Changes in Net Assets Available for Benefits Sheet http://metropolitanbankny.com/role/StatementStatementOfChangesInNetAssetsAvailableForBenefits Statement of Changes in Net Assets Available for Benefits Statements 3 false false R4.htm 10101 - Disclosure - Description of the Plan Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlan Description of the Plan Notes 4 false false R5.htm 10201 - Disclosure - Summary of Significant Accounting Policies Sheet http://metropolitanbankny.com/role/DisclosureSummaryOfSignificantAccountingPolicies Summary of Significant Accounting Policies Notes 5 false false R6.htm 10301 - Disclosure - Related Party and Party-In-Interest Transactions Sheet http://metropolitanbankny.com/role/DisclosureRelatedPartyAndPartyInInterestTransactions Related Party and Party-In-Interest Transactions Notes 6 false false R7.htm 10401 - Disclosure - Fair Value Measurement Sheet http://metropolitanbankny.com/role/DisclosureFairValueMeasurement Fair Value Measurement Notes 7 false false R8.htm 10501 - Disclosure - Plan Termination Sheet http://metropolitanbankny.com/role/DisclosurePlanTermination Plan Termination Notes 8 false false R9.htm 10601 - Disclosure - Income Tax Status Sheet http://metropolitanbankny.com/role/DisclosureIncomeTaxStatus Income Tax Status Notes 9 false false R10.htm 10701 - Disclosure - Risks, Uncertainties, and Concentrations Sheet http://metropolitanbankny.com/role/DisclosureRisksUncertaintiesAndConcentrations Risks, Uncertainties, and Concentrations Notes 10 false false R11.htm 10801 - Disclosure - SECURE Act 2.0 Sheet http://metropolitanbankny.com/role/DisclosureSecureAct20 SECURE Act 2.0 Notes 11 false false R12.htm 10901 - Disclosure - Schedule H, Line 4i - Schedule of Assets (Held at End of Year) Sheet http://metropolitanbankny.com/role/DisclosureScheduleHLine4iScheduleOfAssetsHeldAtEndOfYear Schedule H, Line 4i - Schedule of Assets (Held at End of Year) Notes 12 false false R13.htm 20102 - Disclosure - Summary of Significant Accounting Policies (Policies) Sheet http://metropolitanbankny.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies Summary of Significant Accounting Policies (Policies) Policies http://metropolitanbankny.com/role/DisclosureSummaryOfSignificantAccountingPolicies 13 false false R14.htm 30103 - Disclosure - Description of the Plan (Tables) Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanTables Description of the Plan (Tables) Tables http://metropolitanbankny.com/role/DisclosureDescriptionOfPlan 14 false false R15.htm 30403 - Disclosure - Fair Value Measurement (Tables) Sheet http://metropolitanbankny.com/role/DisclosureFairValueMeasurementTables Fair Value Measurement (Tables) Tables http://metropolitanbankny.com/role/DisclosureFairValueMeasurement 15 false false R16.htm 40101 - Disclosure - Description of the Plan - Contributions and Investment Options (Details) Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanContributionsAndInvestmentOptionsDetails Description of the Plan - Contributions and Investment Options (Details) Details 16 false false R17.htm 40102 - Disclosure - Description of the Plan - Vesting (Details) Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanVestingDetails Description of the Plan - Vesting (Details) Details 17 false false R18.htm 40103 - Disclosure - Description of the Plan - Forfeitures (Details) Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanForfeituresDetails Description of the Plan - Forfeitures (Details) Details 18 false false R19.htm 40104 - Disclosure - Description of the Plan - Notes Receivable from Participants (Details) Notes http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanNotesReceivableFromParticipantsDetails Description of the Plan - Notes Receivable from Participants (Details) Details 19 false false R20.htm 40105 - Disclosure - Description of the Plan - Payment of Benefits (Details) Sheet http://metropolitanbankny.com/role/DisclosureDescriptionOfPlanPaymentOfBenefitsDetails Description of the Plan - Payment of Benefits (Details) Details 20 false false R21.htm 40301 - Disclosure - Related Party and Party-In-Interest Transactions (Details) Sheet http://metropolitanbankny.com/role/DisclosureRelatedPartyAndPartyInInterestTransactionsDetails Related Party and Party-In-Interest Transactions (Details) Details http://metropolitanbankny.com/role/DisclosureRelatedPartyAndPartyInInterestTransactions 21 false false R22.htm 40401 - Disclosure - Fair Value Measurement (Details) Sheet http://metropolitanbankny.com/role/DisclosureFairValueMeasurementDetails Fair Value Measurement (Details) Details http://metropolitanbankny.com/role/DisclosureFairValueMeasurementTables 22 false false R23.htm 40501 - Disclosure - Plan Termination (Details) Sheet http://metropolitanbankny.com/role/DisclosurePlanTerminationDetails Plan Termination (Details) Details http://metropolitanbankny.com/role/DisclosurePlanTermination 23 false false R24.htm 40601 - Disclosure - Income Tax Status (Details) Sheet http://metropolitanbankny.com/role/DisclosureIncomeTaxStatusDetails Income Tax Status (Details) Details http://metropolitanbankny.com/role/DisclosureIncomeTaxStatus 24 false false R25.htm 40701 - Disclosure - Risks, Uncertainties, and Concentrations (Details) Sheet http://metropolitanbankny.com/role/DisclosureRisksUncertaintiesAndConcentrationsDetails Risks, Uncertainties, and Concentrations (Details) Details http://metropolitanbankny.com/role/DisclosureRisksUncertaintiesAndConcentrations 25 false false R26.htm 40801 - Disclosure - Schedule H, Line 4i - Schedule of Assets (Held at End of Year) (Details) Sheet http://metropolitanbankny.com/role/DisclosureScheduleHLine4iScheduleOfAssetsHeldAtEndOfYearDetails Schedule H, Line 4i - Schedule of Assets (Held at End of Year) (Details) Details http://metropolitanbankny.com/role/DisclosureScheduleHLine4iScheduleOfAssetsHeldAtEndOfYear 26 false false All Reports Book All Reports mcb-20251231.xsd mcb-20251231_cal.xml mcb-20251231_def.xml mcb-20251231_lab.xml mcb-20251231_pre.xml mcb-20251231x11k.htm http://fasb.org/us-gaap-ebp/2026 http://xbrl.sec.gov/dei/2026 true true