Document And Entity Information Note To Financial Statement Details Textual Significant Accounting Policies Note 2 - Loans Receivable Income tax benefit ecd_NonRule10b51ArrTrmntdFlag Non-Rule 10b5-1 Arrangement Terminated [Flag] Note 3 - Deposits ecd_NonRule10b51ArrAdoptedFlag Non-Rule 10b5-1 Arrangement Adopted [Flag] Note 4 - Earnings (Loss) Per Share Trading Arrangements, by Individual [Table] Note 7 - Regulatory Matters Depreciation Material Terms of Trading Arrangement [Text Block] Note 8 - Fair Value Measures Proceeds from stock conversion deposited The proceeds from the conversion of stock. Related and Nonrelated Parties [Axis] Note 2 - Loans Receivable - Summary of Loans (Details) Financial Instrument [Axis] Note 2 - Loans Receivable - Past Due (Details) Note 2 - Loans Receivable - Credit Quality Indicators (Details) Note 2 - Loans Receivable - Allowance for Credit Losses (Details) us-gaap_StockRepurchasedAndRetiredDuringPeriodShares Repurchase of common stock (in shares) Note 2 - Loans Receivable - Related Party Loans (Details) Note 3 - Deposits - Schedule of Deposit Liabilities (Details) Note 3 - Deposits - Schedule of Time Deposit Maturities (Details) Note 4 - Earnings (Loss) Per Share - Schedule of Weighted Average Number of Shares (Details) Note 7 - Regulatory Matters - Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations (Details) Note 8 - Fair Value Measures - Assets Measured on a Nonrecurring Basis (Details) Note 8 - Fair Value Measures - Summary of Fair Value by Balance Sheet Grouping (Details) Notes To Financial Statements Notes To Financial Statements [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: CASH FLOWS FROM INVESTING ACTIVITIES: us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by (used in) operating activities CASH FLOWS FROM FINANCING ACTIVITIES: us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash provided by (used in) investing activities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash used in financing activities Advance payments by borrowers for insurance and taxes us-gaap_AssetsFairValueDisclosure Loans individually evaluated Decrease in deposits, net Advertising Salaries and employee benefits ESOP, shares (in shares) Accounting Policies [Abstract] Financial Instruments [Domain] us-gaap_DeferredCompensationEquity Unearned ESOP stock- 63,365 and 64,476 shares at June 30, 2026 and December 31,2025, respectively us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss Loans receivable, net us-gaap_PaymentsForProceedsFromLoansAndLeases Decrease (increase) in loans receivable, net Income Statement [Abstract] us-gaap_SharesOutstanding Balance (in shares) Balance (in shares) Net change in: us-gaap_NumberOfOperatingSegments Number of Operating Segments Segment Reporting [Text Block] mban_TimeDepositMaturitiesYearFiveAndThereafter Thereafter Amount of time deposit maturing in fifth fiscal year and the years thereafter following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Net loss Net Loss Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Preferred stock, $.01 par value - 2,000,000 shares authorized, none issued Banking Regulation, Regulatory Capital Requirement, Compliance [Table] us-gaap_Liabilities Total Liabilities LIABILITIES Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts Issuance cost of common stock us-gaap_LiabilitiesAndStockholdersEquity TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY Segment Reporting [Table] us-gaap_InterestIncomeExpenseNet Net interest income Stock based compensation Individually Evaluated Loans [Member] Represents the individually evaluated loans. Restricted Stock [Member] ESOP expense us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense Preferred Stock, Shares Issued (in shares) Accounting Standards Update and Change in Accounting Principle [Table] Preferred Stock, Shares Authorized (in shares) Portion at Fair Value Measurement [Member] Reported Value Measurement [Member] Fair Value, by Balance Sheet Grouping [Table] Preferred Stock, Par Value (in dollars per share) us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Net change in cash and cash equivalents Occupancy and equipment Other expenses Related and Nonrelated Parties [Domain] us-gaap_RelatedPartyDepositLiabilities Related Party Deposit Liabilities Cash and cash equivalents us-gaap_CashAndCashEquivalentsFairValueDisclosure Estimate of Fair Value Measurement [Member] Related Party Transaction [Table] us-gaap_NoninterestIncome Total noninterest income Common Equity Tier 1 Risk-Based Capital Ratio, Ratio Noninterest Income Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum New Accounting Pronouncements, Policy [Policy Text Block] Total Risk-Based Capital Ratio, Ratio Unvested Stock Options [Member] Represents the unvested stock options. us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Total Risk-Based Capital Antidilutive Securities, Name [Domain] Tier 1 Leverage Ratio, Ratio Banking Regulation, Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Tier 1 Leverage Capital Ratio, Capital Adequacy, Minimum Measurement Basis [Axis] Statement [Table] Banking Regulation, Tier 1 Leverage Capital Ratio, Well Capitalized, Minimum Certificates of deposit Total Fair Value Hierarchy and NAV [Domain] Other income Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Measurement Frequency [Domain] Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Banking Regulation, Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Tier 1 Risk-Based Capital Ratio, Ratio Accrued expense and other liabilities Loans receivable, net us-gaap_LoansReceivableFairValueDisclosure Statement of Financial Position [Abstract] General insurance Deposit Liability [Table] us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit Time Deposits, at or Above FDIC Insurance Limit Provision for credit losses FHLB stock us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure Financing Receivable, Allowance for Credit Loss [Table Text Block] Financing Receivable, Past Due [Table Text Block] Recoveries us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff Loans receivable, before allowance and fee, write offs Charge-offs Other assets Financing Receivable Credit Quality Indicators [Table Text Block] Fair Value, Nonrecurring [Member] Accounting and auditing expenses Legal fees Common Equity Tier 1 Risk-Based Capital Ratio, Amount Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Capital Adequacy, Minimum us-gaap_PaymentsForRepurchaseOfCommonStock Payments to repurchase common stock us-gaap_IncreaseDecreaseInDeferredIncomeTaxes Deferred taxes Document Type Asset Class [Axis] Document Information [Line Items] Document Quarterly Report us-gaap_ConcentrationRiskPercentage1 Concentration Risk, Percentage Document Information [Table] Interest and fees on loans Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Well Capitalized, Minimum us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) Antidilutive Securities [Axis] us-gaap_WeightedAverageNumberOfSharesEmployeeStockOwnershipPlanSharesNotCommittedToBeReleased Less average unearned ESOP shares (in shares) Commitments to Extend Credit [Member] Entity Interactive Data Current Measurement Frequency [Axis] Document Transition Report Commitments and Contingencies Disclosure [Text Block] Statement [Line Items] Fair Value Hierarchy and NAV [Axis] Common Stock, Shares, Issued (in shares) Increase in advances by borrowers for insurance and taxes Common Stock, Shares, Outstanding (in shares) Common Stock, Shares Authorized (in shares) Weighted average shares outstanding (in shares) Loss per share - basic and diluted (in dollars per share) Proceeds from stock issuance, net of offering costs us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance Financing Receivable, Excluding Accrued Interest, Nonaccrual, No Allowance Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] Common Stock, $.01 par value - 6,000,000 shares authorized; 832,288 and 833,750 issued and outstanding at June 30, 2026 and December 31, 2025, respectively Interest-bearing demand deposits Interest bearing deposits Schedule of Weighted Average Number of Shares [Table Text Block] us-gaap_Deposits Total deposits Deposit Liabilities Disclosures [Text Block] us-gaap_PolicyTextBlockAbstract Accounting Policies us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_TableTextBlock Notes Tables Noninterest-bearing deposits Document Fiscal Period Focus Customer [Domain] Document Fiscal Year Focus Automobile depreciation and expense Savings deposits Amendment Flag Financing Receivables [Text Block] Common Stock [Member] Financing Receivable, Past Due [Table] Concentration Risk Type [Axis] Document Period End Date Interest Income Unamortized, net deferred loan costs Deposits Liabilities [Member] Represents deposits liabilities. Residential Portfolio Segment [Member] Legal Entity [Axis] mban_NumberOfMajorCustomers Number of Major Customers Represents the number of major customers accounting for 10% or more of the specified concentration risk benchmark, which includes, but not limited to, sales revenue, accounts receivable, etc. Related Party [Member] Significant Accounting Policies [Text Block] Correspondent charges Amount of expense for FHLB and DDA charges. Commercial Real Estate Portfolio Segment [Member] Financing Receivable, Allowance for Credit Loss [Table] Entity File Number Financial Asset, 30 to 90 Days Past Due [Member] Financial asset more than 29 days past due but fewer than 90 days past due. Entity Tax Identification Number Schedule of Related Party Transactions [Table Text Block] us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment Collectively Evaluated for Impairment Construction Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to construction. One Customer [Member] Represents one customer. Entity [Domain] Entity Central Index Key Entity Registrant Name Share Loans [Member] Loans secured by savings or certificate of deposit accounts of customers. Deposits us-gaap_DepositsFairValueDisclosure Entity Current Reporting Status Special Mention [Member] Entity Incorporation, State or Country Code Pass [Member] Current Fiscal Year End Date Concentration Risk Type [Domain] Entity Ex Transition Period Classified [Member] Credit rating classification which identifies weaknesses related to credit risk. Entity Filer Category Entity Shell Company us-gaap_TimeDepositMaturitiesRemainderOfFiscalYear 2026 Entity Emerging Growth Company Entity Small Business mban_FinancingReceivableExcludeAccruedInterestBeforeAllowanceForCreditLossProceedsForLoanRepayment Payments Amount of increase in financing receivable from proceeds for repayment of loan, exclude accrued interest. Excludes financing receivable covered under loss sharing agreement and net investment in lease. Unearned ESOP compensation, Shares (in shares) Number of of stock issued under share-based plans to employees or officers which is the unearned portion, accounted for under the fair value method. Additions Amount of increase in financing receivable excluded accrued interest from new loan. Excludes financing receivable covered under loss sharing agreement and net investment in lease. Federal Home Loan Bank stock, at cost mban_PaymentsOfRefundOfStockSubscriptions Refund of stock subscriptions The cash outflow for refund of stock subscriptions. Deposits Entity Address, State or Province Statement of Stockholders' Equity [Abstract] mban_PolicyTable mban_NoncashStockDividends FHLB stock dividends Amount of noncash adjustments from stock dividends. Entity Address, City or Town us-gaap_InterestExpenseOperating Total interest expense Retained earnings Entity Address, Address Line One Statement of Cash Flows [Abstract] City Area Code Financing Receivable Portfolio Segment [Axis] Interest Expense Local Phone Number Entity Address, Postal Zip Code us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities Accrued expenses and other liabilities us-gaap_IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets Accrued interest receivable and other assets STOCKHOLDERS' EQUITY Equity Components [Axis] us-gaap_PaymentsOfStockIssuanceCosts Stock issuance costs paid Real Estate Loan [Member] Financing Receivable Portfolio Segment [Domain] Class of Stock [Axis] Equity Component [Domain] Fair Value Measurements, Nonrecurring [Table Text Block] Loans receivable, Past due greater than 90 days accruing Class of Financing Receivable [Axis] Fair Value, Inputs, Level 2 [Member] Class of Financing Receivable [Domain] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 1 [Member] Entity Common Stock, Shares Outstanding Additional Paid-in Capital [Member] Retained Earnings [Member] Earnings Per Share [Text Block] Financing Receivable, Credit Quality Indicator [Table] Loans receivable, before allowance and fee Loans receivable, before allowance and fee Internal Credit Assessment [Axis] Weighted average common shares outstanding (in shares) us-gaap_WeightedAverageNumberOfSharesIssuedBasic Financial Asset, Aging [Axis] Property and equipment, net us-gaap_FairValueDisclosureOffbalanceSheetRisksAmountLiability Fair Value Disclosure, off-Balance-Sheet Risks, Amount, Liability Loans receivable Balance, Beginning Balance, Ending us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss Net interest income after provision for credit losses Financial Asset, Aging [Domain] Other Internal Credit Assessment [Domain] us-gaap_ProvisionForLoanLeaseAndOtherLosses Provision for credit losses Common Stock, Par Value (in dollars per share) Stock compensation us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 Individually Evaluated for Impairment Basis of Accounting, Policy [Policy Text Block] us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest Less allowance for credit losses Beginning Balance Ending Balances Financial Asset, Equal to or Greater than 90 Days Past Due [Member] ESOP shares committed to be released Deferred Compensation, Share-Based Payments [Member] Regulatory Capital Requirements under Banking Regulations [Text Block] Cash and due from banks us-gaap_Assets TOTAL ASSETS us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear Financing receivable, originated year five us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear Financing receivable, originated prior us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear Financing receivable, originated year three us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear Financing receivable, originated year four us-gaap_InterestIncomeOperating Total interest income Fair Value Disclosures [Text Block] us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear Financing receivable, originated current year Fair Value, by Balance Sheet Grouping [Table Text Block] us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear Financing receivable, originated year two SUPPLEMENTAL DISCLOSURES FOR CASH FLOW INFORMATION: Customer [Axis] Time Deposit Maturities [Table Text Block] Customer Concentration Risk [Member] Asset Class [Domain] Accounts and Financing Receivables [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Accrued interest receivable Cash paid during the period for interest Banking Regulation, Tier 1 Risk-Based Capital, Capital Adequacy, Minimum Other Commitments [Table] Banking Regulation, Tier 1 Risk-Based Capital, Well Capitalized, Minimum Banking Regulation, Tier 1 Risk-Based Capital, Actual Banking Regulation, Tier 1 Leverage Capital, Capital Adequacy, Minimum Banking Regulation, Tier 1 Leverage Capital, Well Capitalized, Minimum Banking Regulation, Tier 1 Leverage Capital, Actual us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff Financing receivable, originated prior, write offs us-gaap_TimeDepositMaturitiesYearThree 2029 us-gaap_TimeDepositMaturitiesYearTwo 2028 us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff Financing receivable, originated year four, write offs us-gaap_TimeDepositMaturitiesYearFour 2030 us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff Financing receivable, originated year five, write offs us-gaap_TimeDepositMaturitiesYearOne 2027 us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff Financing receivable, originated year two, write offs us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff Financing receivable, originated year three, write offs us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff Financing receivable, originated current year, write offs us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest Loss before income taxes Data processing Additional paid-in capital Deposit Liabilities, Type [Table Text Block] us-gaap_StockholdersEquity Total Stockholders' Equity Balance Balance Use of Estimates, Policy [Policy Text Block] Banking Regulation, Total Risk-Based Capital, Capital Adequacy, Minimum us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan Purchase of common shares for ESOP Total Risk-Based Capital Ratio, Amount Issuance of common stock us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchases of property and equipment Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] us-gaap_StockRepurchasedAndRetiredDuringPeriodValue Repurchase of common stock us-gaap_NoninterestExpense Total noninterest expense Noninterest Expense Financial Asset, Not Past Due [Member] Banking Regulation, Total Risk-Based Capital, Well Capitalized, Minimum Fair Value, Recurring and Nonrecurring [Table] ecd_Rule10b51ArrTrmntdFlag Rule 10b5-1 Arrangement Terminated [Flag] Service charges on deposit accounts ecd_Rule10b51ArrAdoptedFlag Rule 10b5-1 Arrangement Adopted [Flag] Issuance of common stock (in shares)