3.23.1 html 454 394 1 true 87 0 false 7 false false R1.htm 000 - Document - Document And Entity Information Sheet http://www.mercbank.com/20230331/role/statement-document-and-entity-information Document And Entity Information Cover 1 false false R2.htm 001 - Statement - Consolidated Balance Sheets (Current Period Unaudited) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-balance-sheets-current-period-unaudited Consolidated Balance Sheets (Current Period Unaudited) Statements 2 false false R3.htm 002 - Statement - Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-balance-sheets-current-period-unaudited-parentheticals Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) Statements 3 false false R4.htm 003 - Statement - Consolidated Statements of Income (Unaudited) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-statements-of-income-unaudited Consolidated Statements of Income (Unaudited) Statements 4 false false R5.htm 004 - Statement - Consolidated Statements of Comprehensive Income (Loss) (Unaudited) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-statements-of-comprehensive-income-loss-unaudited Consolidated Statements of Comprehensive Income (Loss) (Unaudited) Statements 5 false false R6.htm 005 - Statement - Consolidated Statements of Changes in Shareholders' Equity (Unaudited) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-statements-of-changes-in-shareholders-equity-unaudited Consolidated Statements of Changes in Shareholders' Equity (Unaudited) Statements 6 false false R7.htm 006 - Statement - Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parentheticals) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-statements-of-changes-in-shareholders-equity-unaudited-parentheticals Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parentheticals) Statements 7 false false R8.htm 007 - Statement - Consolidated Statements of Cash Flows (Unaudited) Sheet http://www.mercbank.com/20230331/role/statement-consolidated-statements-of-cash-flows-unaudited Consolidated Statements of Cash Flows (Unaudited) Statements 8 false false R9.htm 008 - Disclosure - Note 1 - Significant Accounting Policies Sheet http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies Note 1 - Significant Accounting Policies Notes 9 false false R10.htm 009 - Disclosure - Note 2 - Securities Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities Note 2 - Securities Notes 10 false false R11.htm 010 - Disclosure - Note 3 - Loans and Allowance for Credit Losses Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses Note 3 - Loans and Allowance for Credit Losses Notes 11 false false R12.htm 011 - Disclosure - Note 4 - Premises and Equipment, Net Sheet http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net Note 4 - Premises and Equipment, Net Notes 12 false false R13.htm 012 - Disclosure - Note 5 - Deposits Sheet http://www.mercbank.com/20230331/role/statement-note-5-deposits Note 5 - Deposits Notes 13 false false R14.htm 013 - Disclosure - Note 6 - Securities Sold Under Agreements to Repurchase Sheet http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase Note 6 - Securities Sold Under Agreements to Repurchase Notes 14 false false R15.htm 014 - Disclosure - Note 7 - Federal Home Loan Bank of Indianapolis Advances Sheet http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances Note 7 - Federal Home Loan Bank of Indianapolis Advances Notes 15 false false R16.htm 015 - Disclosure - Note 8 - Commitments and Off-balance Sheet Risk Sheet http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk Note 8 - Commitments and Off-balance Sheet Risk Notes 16 false false R17.htm 016 - Disclosure - Note 9 - Derivatives and Hedging Activities Sheet http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities Note 9 - Derivatives and Hedging Activities Notes 17 false false R18.htm 017 - Disclosure - Note 10 - Fair Values of Financial Instruments Sheet http://www.mercbank.com/20230331/role/statement-note-10-fair-values-of-financial-instruments Note 10 - Fair Values of Financial Instruments Notes 18 false false R19.htm 018 - Disclosure - Note 11 - Fair Values Sheet http://www.mercbank.com/20230331/role/statement-note-11-fair-values Note 11 - Fair Values Notes 19 false false R20.htm 019 - Disclosure - Note 12 - Regulatory Matters Sheet http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters Note 12 - Regulatory Matters Notes 20 false false R21.htm 020 - Disclosure - Note 13 - Subsequent Events Sheet http://www.mercbank.com/20230331/role/statement-note-13-subsequent-events Note 13 - Subsequent Events Notes 21 false false R22.htm 021 - Disclosure - Significant Accounting Policies (Policies) Sheet http://www.mercbank.com/20230331/role/statement-significant-accounting-policies-policies Significant Accounting Policies (Policies) Policies http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies 22 false false R23.htm 022 - Disclosure - Note 1 - Significant Accounting Policies (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies-tables Note 1 - Significant Accounting Policies (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies 23 false false R24.htm 023 - Disclosure - Note 2 - Securities (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities-tables Note 2 - Securities (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-2-securities 24 false false R25.htm 024 - Disclosure - Note 3 - Loans and Allowance for Credit Losses (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-tables Note 3 - Loans and Allowance for Credit Losses (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses 25 false false R26.htm 025 - Disclosure - Note 4 - Premises and Equipment, Net (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net-tables Note 4 - Premises and Equipment, Net (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net 26 false false R27.htm 026 - Disclosure - Note 5 - Deposits (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-5-deposits-tables Note 5 - Deposits (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-5-deposits 27 false false R28.htm 027 - Disclosure - Note 6 - Securities Sold Under Agreements to Repurchase (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase-tables Note 6 - Securities Sold Under Agreements to Repurchase (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase 28 false false R29.htm 028 - Disclosure - Note 7 - Federal Home Loan Bank of Indianapolis Advances (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances-tables Note 7 - Federal Home Loan Bank of Indianapolis Advances (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances 29 false false R30.htm 029 - Disclosure - Note 8 - Commitments and Off-balance Sheet Risk (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk-tables Note 8 - Commitments and Off-balance Sheet Risk (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk 30 false false R31.htm 030 - Disclosure - Note 9 - Derivatives and Hedging Activities (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities-tables Note 9 - Derivatives and Hedging Activities (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities 31 false false R32.htm 031 - Disclosure - Note 10 - Fair Values of Financial Instruments (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-10-fair-values-of-financial-instruments-tables Note 10 - Fair Values of Financial Instruments (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-10-fair-values-of-financial-instruments 32 false false R33.htm 032 - Disclosure - Note 11 - Fair Values (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-11-fair-values-tables Note 11 - Fair Values (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-11-fair-values 33 false false R34.htm 033 - Disclosure - Note 12 - Regulatory Matters (Tables) Sheet http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters-tables Note 12 - Regulatory Matters (Tables) Tables http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters 34 false false R35.htm 034 - Disclosure - Note 1 - Significant Accounting Policies (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies-details-textual Note 1 - Significant Accounting Policies (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies-tables 35 false false R36.htm 035 - Disclosure - Note 1 - Significant Accounting Policies - Noninterest Income (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-1-significant-accounting-policies-noninterest-income-details Note 1 - Significant Accounting Policies - Noninterest Income (Details) Details 36 false false R37.htm 036 - Disclosure - Note 2 - Securities (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities-details-textual Note 2 - Securities (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-2-securities-tables 37 false false R38.htm 037 - Disclosure - Note 2 - Securities - Available-for-sale Securities (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities-availableforsale-securities-details Note 2 - Securities - Available-for-sale Securities (Details) Details 38 false false R39.htm 038 - Disclosure - Note 2 - Securities - Securities in a Continuous Loss Position (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities-securities-in-a-continuous-loss-position-details Note 2 - Securities - Securities in a Continuous Loss Position (Details) Details 39 false false R40.htm 039 - Disclosure - Note 2 - Securities - Debt Securities by Maturity (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-2-securities-debt-securities-by-maturity-details Note 2 - Securities - Debt Securities by Maturity (Details) Details 40 false false R41.htm 040 - Disclosure - Note 3 - Loans and Allowance for Credit Losses (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-details-textual Note 3 - Loans and Allowance for Credit Losses (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-tables 41 false false R42.htm 041 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Components of Loan Portfolio (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-components-of-loan-portfolio-details Note 3 - Loans and Allowance for Credit Losses - Components of Loan Portfolio (Details) Details 42 false false R43.htm 042 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Nonperforming Loans (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-nonperforming-loans-details Note 3 - Loans and Allowance for Credit Losses - Nonperforming Loans (Details) Details 43 false false R44.htm 043 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Age Analysis of Past Due Loans (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-age-analysis-of-past-due-loans-details Note 3 - Loans and Allowance for Credit Losses - Age Analysis of Past Due Loans (Details) Details 44 false false R45.htm 044 - Disclosure - Note 3 - Loans and Allowance for Loan Losses - Nonaccrual Loans (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-loan-losses-nonaccrual-loans-details Note 3 - Loans and Allowance for Loan Losses - Nonaccrual Loans (Details) Details 45 false false R46.htm 045 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Loan Vintage (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-loan-vintage-details Note 3 - Loans and Allowance for Credit Losses - Loan Vintage (Details) Details 46 false false R47.htm 046 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-activity-in-allowance-for-loan-losses-and-the-recorded-investments-in-loans-details Note 3 - Loans and Allowance for Credit Losses - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (Details) Details 47 false false R48.htm 047 - Disclosure - Note 3 - Loans and Allowance for Credit Losses - Loans Modified as Troubled Debt Restructurings (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-credit-losses-loans-modified-as-troubled-debt-restructurings-details Note 3 - Loans and Allowance for Credit Losses - Loans Modified as Troubled Debt Restructurings (Details) Details 48 false false R49.htm 048 - Disclosure - Note 3 - Loans and Allowance for Loan Losses - Loans Modified As Troubled Debt Restructurings Within the Previous Twelve Months That Became Over 30 Days Past Due (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-loan-losses-loans-modified-as-troubled-debt-restructurings-within-the-previous-twelve-months-that-became-over-30-days-past-due-details Note 3 - Loans and Allowance for Loan Losses - Loans Modified As Troubled Debt Restructurings Within the Previous Twelve Months That Became Over 30 Days Past Due (Details) Details 49 false false R50.htm 049 - Disclosure - Note 3 - Loans and Allowance for Loan Losses - Activity for Troubled Debt Restructurings (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-3-loans-and-allowance-for-loan-losses-activity-for-troubled-debt-restructurings-details Note 3 - Loans and Allowance for Loan Losses - Activity for Troubled Debt Restructurings (Details) Details 50 false false R51.htm 050 - Disclosure - Note 4 - Premises and Equipment, Net (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net-details-textual Note 4 - Premises and Equipment, Net (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net-tables 51 false false R52.htm 051 - Disclosure - Note 4 - Premises and Equipment, Net - Summary of Premises and Equipment (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net-summary-of-premises-and-equipment-details Note 4 - Premises and Equipment, Net - Summary of Premises and Equipment (Details) Details 52 false false R53.htm 052 - Disclosure - Note 4 - Premises and Equipment, Net - Future Lease Payments (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-4-premises-and-equipment-net-future-lease-payments-details Note 4 - Premises and Equipment, Net - Future Lease Payments (Details) Details 53 false false R54.htm 053 - Disclosure - Note 5 - Deposits (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-5-deposits-details-textual Note 5 - Deposits (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-5-deposits-tables 54 false false R55.htm 054 - Disclosure - Note 5 - Deposits - Summary of Deposits (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-5-deposits-summary-of-deposits-details Note 5 - Deposits - Summary of Deposits (Details) Details 55 false false R56.htm 055 - Disclosure - Note 6 - Securities Sold Under Agreements to Repurchase (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase-details-textual Note 6 - Securities Sold Under Agreements to Repurchase (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase-tables 56 false false R57.htm 056 - Disclosure - Note 6 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-6-securities-sold-under-agreements-to-repurchase-securities-sold-under-agreement-to-repurchase-details Note 6 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) Details 57 false false R58.htm 057 - Disclosure - Note 7 - Federal Home Loan Bank of Indianapolis Advances (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances-details-textual Note 7 - Federal Home Loan Bank of Indianapolis Advances (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances-tables 58 false false R59.htm 058 - Disclosure - Note 7 - Federal Home Loan Bank of Indianapolis Advances - Maturities of Currently Outstanding FHLB Advances (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances-maturities-of-currently-outstanding-fhlb-advances-details Note 7 - Federal Home Loan Bank of Indianapolis Advances - Maturities of Currently Outstanding FHLB Advances (Details) Details 59 false false R60.htm 059 - Disclosure - Note 7 - Federal Home Loan Bank of Indianapolis Advances - Maturities of Currently Outstanding FHLBI Amortizing Advances (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-7-federal-home-loan-bank-of-indianapolis-advances-maturities-of-currently-outstanding-fhlbi-amortizing-advances-details Note 7 - Federal Home Loan Bank of Indianapolis Advances - Maturities of Currently Outstanding FHLBI Amortizing Advances (Details) Details 60 false false R61.htm 060 - Disclosure - Note 8 - Commitments and Off-balance Sheet Risk (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk-details-textual Note 8 - Commitments and Off-balance Sheet Risk (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk-tables 61 false false R62.htm 061 - Disclosure - Note 8 - Commitments and Off-balance Sheet Risk - Exposure to Credit Losses (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-8-commitments-and-offbalance-sheet-risk-exposure-to-credit-losses-details Note 8 - Commitments and Off-balance Sheet Risk - Exposure to Credit Losses (Details) Details 62 false false R63.htm 062 - Disclosure - Note 9 - Derivatives and Hedging Activities (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities-details-textual Note 9 - Derivatives and Hedging Activities (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities-tables 63 false false R64.htm 063 - Disclosure - Note 9 - Derivatives and Hedging Activities - Fair Value of Derivative Instruments (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-9-derivatives-and-hedging-activities-fair-value-of-derivative-instruments-details Note 9 - Derivatives and Hedging Activities - Fair Value of Derivative Instruments (Details) Details 64 false false R65.htm 064 - Disclosure - Note 10 - Fair Values of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-10-fair-values-of-financial-instruments-fair-value-hierarchy-of-financial-instruments-details Note 10 - Fair Values of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) Details 65 false false R66.htm 065 - Disclosure - Note 11 - Fair Values (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-11-fair-values-details-textual Note 11 - Fair Values (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-11-fair-values-tables 66 false false R67.htm 066 - Disclosure - Note 11 - Fair Values - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-11-fair-values-assets-and-liabilities-measured-at-fair-value-on-a-recurring-basis-details Note 11 - Fair Values - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Details 67 false false R68.htm 067 - Disclosure - Note 11 - Fair Values - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-11-fair-values-assets-and-liabilities-measured-at-fair-value-on-a-nonrecurring-basis-details Note 11 - Fair Values - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) Details 68 false false R69.htm 068 - Disclosure - Note 12 - Regulatory Matters (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters-details-textual Note 12 - Regulatory Matters (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters-tables 69 false false R70.htm 069 - Disclosure - Note 12 - Regulatory Matters - Actual Capital Levels and Minimum Levels (Details) Sheet http://www.mercbank.com/20230331/role/statement-note-12-regulatory-matters-actual-capital-levels-and-minimum-levels-details Note 12 - Regulatory Matters - Actual Capital Levels and Minimum Levels (Details) Details 70 false false R71.htm 070 - Disclosure - Note 13 - Subsequent Events (Details Textual) Sheet http://www.mercbank.com/20230331/role/statement-note-13-subsequent-events-details-textual Note 13 - Subsequent Events (Details Textual) Details http://www.mercbank.com/20230331/role/statement-note-13-subsequent-events 71 false false All Reports Book All Reports [ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 35 fact(s) appearing in ix:hidden were eligible for transformation: dei:EntityRegistrantName, us-gaap:AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife, us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis, us-gaap:AvailableForSaleSecuritiesDebtSecurities, us-gaap:CommonStockDividendsPerShareCashPaid, us-gaap:CommonStockNoParValue, us-gaap:CommonStockSharesAuthorized, us-gaap:CommonStockSharesOutstanding, us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss, us-gaap:FinancingReceivableModificationsRecordedInvestment, us-gaap:LesseeOperatingLeaseRenewalTerm, us-gaap:OperatingLeaseLiability, us-gaap:PreferredStockNoParValue, us-gaap:PreferredStockSharesAuthorized, us-gaap:PreferredStockSharesOutstanding, us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt, us-gaap:PropertyPlantAndEquipmentGross, us-gaap:RepurchaseAgreementCounterpartyWeightedAverageMaturityOfAgreements1, us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan, us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans, us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised, us-gaap:ValuationAllowancesAndReservesBalance - mbwm20230331_10q.htm 8, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 mbwm20230331_10q.htm ex_510203.htm ex_510208.htm ex_510209.htm mbwm-20230331.xsd mbwm-20230331_cal.xml mbwm-20230331_def.xml mbwm-20230331_lab.xml mbwm-20230331_pre.xml http://fasb.org/us-gaap/2023 http://xbrl.sec.gov/dei/2023 true true