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Disclosure - Note 13 - Operating Lease Commitments and Contingencies (Tables) Sheet http://www.mbtc.com/20251231/role/statement-note-13-operating-lease-commitments-and-contingencies-tables Note 13 - Operating Lease Commitments and Contingencies (Tables) Tables http://www.mbtc.com/20251231/role/statement-note-13-operating-lease-commitments-and-contingencies- 44 false false R45.htm 995585 - Disclosure - Note 14 - Regulatory Matters (Tables) Sheet http://www.mbtc.com/20251231/role/statement-note-14-regulatory-matters-tables Note 14 - Regulatory Matters (Tables) Tables http://www.mbtc.com/20251231/role/statement-note-14-regulatory-matters 45 false false R46.htm 995586 - Disclosure - Note 15 - Commitments and Standby Letters of Credit (Tables) Sheet http://www.mbtc.com/20251231/role/statement-note-15-commitments-and-standby-letters-of-credit-tables Note 15 - Commitments and Standby Letters of Credit (Tables) Tables http://www.mbtc.com/20251231/role/statement-note-15-commitments-and-standby-letters-of-credit 46 false false R47.htm 995587 - 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Loans and Other Real Estate Owned ("OREO") (Details Textual) Details http://www.mbtc.com/20251231/role/statement-note-5-loans-and-other-real-estate-owned-oreo-tables 62 false false R63.htm 995603 - Disclosure - Note 5 - Loans and Other Real Estate Owned ("OREO") - Categories of Loans (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-5-loans-and-other-real-estate-owned-oreo-categories-of-loans-details Note 5 - Loans and Other Real Estate Owned ("OREO") - Categories of Loans (Details) Details http://www.mbtc.com/20251231/role/statement-note-5-loans-and-other-real-estate-owned-oreo-tables 63 false false R64.htm 995604 - Disclosure - Note 5 - Loans - Summary of Loan Activity for Related Parties (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-5-loans-summary-of-loan-activity-for-related-parties-details Note 5 - Loans - Summary of Loan Activity for Related Parties (Details) Details 64 false false R65.htm 995605 - Disclosure - Note 5 - Loans and Other Real Estate Owned ("OREO") - 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Allowance for Credit Losses (Details Textual) Details http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-tables 67 false false R68.htm 995608 - Disclosure - Note 6 - Allowance for Credit Losses - Credit Rating (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-credit-rating-details Note 6 - Allowance for Credit Losses - Credit Rating (Details) Details 68 false false R69.htm 995609 - Disclosure - Note 6 - Allowance for Credit Losses - Past Due (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-past-due-details Note 6 - Allowance for Credit Losses - Past Due (Details) Details 69 false false R70.htm 995610 - Disclosure - Note 6 - Allowance for Credit Losses - Nonaccrual (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-nonaccrual-details Note 6 - Allowance for Credit Losses - Nonaccrual (Details) Details 70 false false R71.htm 995611 - Disclosure - Note 6 - Allowance for Credit Losses - Activity in Allowance for Credit Losses (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-activity-in-allowance-for-credit-losses-details Note 6 - Allowance for Credit Losses - Activity in Allowance for Credit Losses (Details) Details 71 false false R72.htm 995612 - Disclosure - Note 6 - Allowance for Credit Losses - Collateral Dependent Loans (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-collateral-dependent-loans-details Note 6 - Allowance for Credit Losses - Collateral Dependent Loans (Details) Details 72 false false R73.htm 995613 - Disclosure - Note 6 - Allowance for Credit Losses - Summary of Modified Loans (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-summary-of-modified-loans-details Note 6 - Allowance for Credit Losses - Summary of Modified Loans (Details) Details 73 false false R74.htm 995614 - Disclosure - Note 6 - Allowance for Credit Losses - Allowance for Unfunded Commitments (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-6-allowance-for-credit-losses-allowance-for-unfunded-commitments-details Note 6 - Allowance for Credit Losses - Allowance for Unfunded Commitments (Details) Details 74 false false R75.htm 995615 - Disclosure - Note 7 - Premises and Equipment (Details Textual) Sheet http://www.mbtc.com/20251231/role/statement-note-7-premises-and-equipment-details-textual Note 7 - Premises and Equipment (Details Textual) Details http://www.mbtc.com/20251231/role/statement-note-7-premises-and-equipment-tables 75 false false R76.htm 995616 - Disclosure - Note 7 - Premises and Equipment - Classifications of Premises and Equipment (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-7-premises-and-equipment-classifications-of-premises-and-equipment-details Note 7 - Premises and Equipment - Classifications of Premises and Equipment (Details) Details 76 false false R77.htm 995617 - Disclosure - Note 8 - Deposits (Details Textual) Sheet http://www.mbtc.com/20251231/role/statement-note-8-deposits-details-textual Note 8 - Deposits (Details Textual) Details http://www.mbtc.com/20251231/role/statement-note-8-deposits-tables 77 false false R78.htm 995618 - Disclosure - Note 8 - Deposits - Maturity of Time Deposits (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-8-deposits-maturity-of-time-deposits-details Note 8 - Deposits - Maturity of Time Deposits (Details) Details 78 false false R79.htm 995619 - Disclosure - Note 9 - Borrowings and Subordinated Debt (Details Textual) Sheet http://www.mbtc.com/20251231/role/statement-note-9-borrowings-and-subordinated-debt-details-textual Note 9 - Borrowings and Subordinated Debt (Details Textual) Details http://www.mbtc.com/20251231/role/statement-note-9-borrowings-and-subordinated-debt-tables 79 false false R80.htm 995620 - Disclosure - Note 9 - Borrowings and Subordinated Debt - Federal Home Loan Bank Advances (Details) Sheet http://www.mbtc.com/20251231/role/statement-note-9-borrowings-and-subordinated-debt-federal-home-loan-bank-advances-details Note 9 - 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