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Disclosure - Significant Accounting Policies (Policies) Sheet http://www.mstreetbank.com/20241231/role/statement-significant-accounting-policies-policies Significant Accounting Policies (Policies) Policies http://www.mstreetbank.com/20241231/role/statement-note-1-organization-basis-of-presentation-and-impact-of-recently-issued-accounting-pronouncements 38 false false R39.htm 995579 - Disclosure - Note 1 - Organization, Basis of Presentation and Impact of Recently Issued Accounting Pronouncements (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-1-organization-basis-of-presentation-and-impact-of-recently-issued-accounting-pronouncements-tables Note 1 - Organization, Basis of Presentation and Impact of Recently Issued Accounting Pronouncements (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-1-organization-basis-of-presentation-and-impact-of-recently-issued-accounting-pronouncements 39 false false R40.htm 995580 - Disclosure - Note 3 - Investment Securities (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-3-investment-securities-tables Note 3 - 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Disclosure - Note 7 - Premises and Equipment (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-7-premises-and-equipment-tables Note 7 - Premises and Equipment (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-7-premises-and-equipment 44 false false R45.htm 995585 - Disclosure - Note 8 - Intangible Assets (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-8-intangible-assets-tables Note 8 - Intangible Assets (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-8-intangible-assets 45 false false R46.htm 995586 - Disclosure - Note 9 - Deposits (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-9-deposits-tables Note 9 - Deposits (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-9-deposits 46 false false R47.htm 995587 - Disclosure - Note 10 - Borrowed Funds (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-10-borrowed-funds-tables Note 10 - Borrowed Funds (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-10-borrowed-funds 47 false false R48.htm 995588 - Disclosure - Note 11 - Income Taxes (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-11-income-taxes-tables Note 11 - Income Taxes (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-11-income-taxes 48 false false R49.htm 995589 - Disclosure - Note 12 - Earnings Per Common Share (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-12-earnings-per-common-share-tables Note 12 - Earnings Per Common Share (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-12-earnings-per-common-share 49 false false R50.htm 995590 - Disclosure - Note 13 - Commitments and Contingencies (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-13-commitments-and-contingencies-tables Note 13 - Commitments and Contingencies (Tables) Tables http://www.mstreetbank.com/20241231/role/statement-note-13-commitments-and-contingencies- 50 false false R51.htm 995591 - Disclosure - Note 14 - Leases (Tables) Sheet http://www.mstreetbank.com/20241231/role/statement-note-14-leases-tables Note 14 - 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Investment Securities - Summary of Unrealized Loss Positions (Details) Details 68 false false R69.htm 995609 - Disclosure - Note 4 - Loans Receivable (Details Textual) Sheet http://www.mstreetbank.com/20241231/role/statement-note-4-loans-receivable-details-textual Note 4 - Loans Receivable (Details Textual) Details http://www.mstreetbank.com/20241231/role/statement-note-4-loans-receivable-tables 69 false false R70.htm 995610 - Disclosure - Note 4 - Loans Receivable - Schedule of Loans Receivable (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-4-loans-receivable-schedule-of-loans-receivable-details Note 4 - Loans Receivable - Schedule of Loans Receivable (Details) Details 70 false false R71.htm 995611 - Disclosure - Note 4 - Loans Receivable - Segments of the Loan Portfolio by Aging Categories (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-4-loans-receivable-segments-of-the-loan-portfolio-by-aging-categories-details Note 4 - Loans Receivable - 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Allowance for Credit Losses - Summary of Nonaccrual Loans (Details) Details 74 false false R75.htm 995615 - Disclosure - Note 5 - Allowance for Credit Losses - Accrued Interest Receivable Written Off of Loans (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-5-allowance-for-credit-losses-accrued-interest-receivable-written-off-of-loans-details Note 5 - Allowance for Credit Losses - Accrued Interest Receivable Written Off of Loans (Details) Details 75 false false R76.htm 995616 - Disclosure - Note 5 - Allowance for Credit Losses - Schedule of Collateral Dependent Loans (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-5-allowance-for-credit-losses-schedule-of-collateral-dependent-loans-details Note 5 - Allowance for Credit Losses - Schedule of Collateral Dependent Loans (Details) Details 76 false false R77.htm 995617 - Disclosure - Note 5 - Allowance for Credit Losses - Summary of Modified Financing Receivables (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-5-allowance-for-credit-losses-summary-of-modified-financing-receivables-details Note 5 - Allowance for Credit Losses - Summary of Modified Financing Receivables (Details) Details 77 false false R78.htm 995618 - Disclosure - Note 5 - Allowance for Credit Losses - Summary of Credit Quality Indicators (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-5-allowance-for-credit-losses-summary-of-credit-quality-indicators-details Note 5 - Allowance for Credit Losses - Summary of Credit Quality Indicators (Details) Details 78 false false R79.htm 995619 - Disclosure - Note 5 - Allowance for Credit Losses - Off-balance Sheet Credit Exposure (Details) Sheet http://www.mstreetbank.com/20241231/role/statement-note-5-allowance-for-credit-losses-offbalance-sheet-credit-exposure-details Note 5 - Allowance for Credit Losses - Off-balance Sheet Credit Exposure (Details) Details 79 false false R80.htm 995620 - Disclosure - Note 6 - Related Party Transactions (Details Textual) Sheet http://www.mstreetbank.com/20241231/role/statement-note-6-related-party-transactions-details-textual Note 6 - 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