Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Principles of Consolidation and Basis of Presentation The consolidated financial statements of Middlefield Banc Corp. ("Company") include its bank subsidiary, The Middlefield Banking Company (“MBC” or “Bank”), and a nonbank asset resolution subsidiary EMORECO, Inc. The consolidated financial statements also include the accounts of MBC’s subsidiaries, Middlefield Investments, Inc. (“MI”) and MB Insurance Services (“MIS”). All significant inter-company items have been eliminated. On March 13, 2019, MBC established MI as an operating subsidiary to hold and manage an investment portfolio. On December 31, 2024, MI’s assets consist of a cash account, investments, and related accrued interest accounts. MI may only hold and manage investments and may not engage in any other activity without prior approval of the Ohio Division of Financial Institutions. In the first quarter of 2022, MBC established MIS as an operating subsidiary to offer retail and business customers various insurance services, including home, renters, automobile, pet, identity theft, travel, and professional liability insurance. On December 31, 2024, MIS assets consist of a cash account, a prepaid asset, and an accounts receivable. As a result of the bank merger of Liberty National Bank and MBC on December 1, 2022, Middlefield Banc Corp. acquired a 100% ownership interest in LBSI Insurance, LLC (“LBSI”), a wholly owned financial subsidiary of Liberty National Bank. LBSI did not operate after the merger, and its existence ended January 19, 2024. All significant intercompany items have been eliminated between MBC and these subsidiaries. On December 1, 2022, the Company completed its merger with Liberty Bancshares, Inc. (“Liberty’), pursuant to a previously announced definitive merger agreement. Under the terms of the merger agreement, Liberty shareholders received 2.752 shares of the Company’s common stock in exchange for each share of Liberty common stock they owned immediately before the merger. The Company issued 2,561,513 shares of its common stock in the merger, and the aggregate merger consideration was approximately $73.3 million. Upon closing, Liberty’s bank subsidiary was merged into MBC, and Liberty’s six full-service bank offices, in Ada and Kenton in Hardin County, Bellefontaine North and Bellefontaine South in Logan County, Marysville in Union County, and Westerville in Franklin County, became offices of MBC.
Use of Estimates, Policy [Policy Text Block]	Estimates In preparing the financial statements, management is required to make estimates and assumptions that affect the reported amounts and liabilities as of the balance sheet date and revenues and expenses for the period. Actual results could differ from those estimates.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents The Company has defined cash and cash equivalents as those amounts included in the Consolidated Balance Sheet captions as “Cash and due from banks” and “Federal funds sold” with original maturities of less than 90 days.
Equity Method Investments [Policy Text Block]	Investments Management determines the appropriate classification of investment securities at the time of purchase and re-evaluates such designation as of each balance sheet date. Investment securities classified as available for sale are those securities that the Bank intends to hold for an indefinite period of time but not necessarily to maturity. Securities available for sale are carried at fair value. Any decision to sell a security classified as available for sale would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Bank’s assets and liabilities, liquidity needs, regulatory capital considerations, and other similar factors. Unrealized gains or losses are reported as increases or decreases in other comprehensive income (loss), net of the deferred tax effect. Realized gains or losses, determined on the basis of the cost of the specific securities sold, are included in earnings. Premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Investment securities classified as held to maturity are those securities the Bank has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or changes in general economic conditions. These securities are carried at cost, adjusted for the amortization of premium and accretion of discount, and computed by a method that approximates the interest method over the terms of the securities. As of December 31, 2024, the Company did not hold any held-to-maturity securities. Equity securities, which are included in "other investments" on the Consolidated Balance Sheet, are measured at fair value with changes in fair value recognized in net income.
Marketable Securities, Policy [Policy Text Block]	Allowance for Credit Losses – Investment Securities Available for Sale The Bank adopted ASU No. 2016-13, Financial Instruments - Credit Loses - Topic (326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), effective January 1, 2023. Financial statement amounts related to investment securities recorded as of December 31, 2024 and 2023 are presented in accordance with the accounting policies described in the following sections. The Bank measures expected credit losses on available for sale investment securities when the Bank intends to sell, or when it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value through income. For available for sale investment securities that do not meet the aforementioned criteria, the Bank evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Bank considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this evaluation indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists, and an allowance for credit losses is recorded for the credit loss, equal to the amount that the fair value is less than the amortized cost basis. Economic forecast data is used to calculate the present value of expected cash flows. The Bank obtains its forecast data through a subscription to a widely recognized and relied-upon company that publishes various forecast scenarios. Management evaluates the various scenarios to determine a reasonable and supportable scenario and uses a single scenario in the model. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income. The allowance for credit losses is included within "investment securities available for sale" on the Consolidated Balance Sheet, as applicable. Changes in the allowance for credit losses are recorded within the "provision for credit losses" on the Consolidated Income Statement. Losses are charged against the allowance when the Bank believes the collectability of an available for sale security is in jeopardy or when either of the criteria regarding intent or requirement to sell is met. Accrued interest receivable on available for sale investment securities is included within "accrued interest receivable and other assets" on the Consolidated Balance Sheet. This amount is excluded from the estimate of expected credit losses. Available for sale investment securities are typically classified as nonaccrual when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about the further collectability of principal or interest. When available for sale investment securities are placed on nonaccrual status, unpaid interest credited to income is reversed.
Financing Receivable [Policy Text Block]	Loans Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are stated at their outstanding unpaid principal balances, net of unearned income, which includes net deferred loan fees and costs and unamortized premiums and discounts. Accrued interest receivable is included within "accrued interest receivable and other assets" on the Consolidated Balance Sheet. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loans’ yield (interest income). The Bank amortizes these amounts over the contractual life of the loan. Premiums and discounts on purchased loans are amortized as adjustments to interest income using the effective yield method. Interest income is primarily recognized on an accrual basis according to formulas in written contracts, such as loan agreements. The loan portfolio is segmented into commercial and consumer loans. Commercial loans consist of the following classes: commercial construction, commercial and industrial loans, and commercial real estate loans. Consumer loans consist of the following classes: residential real estate loans, home equity loans, and consumer loans. For all classes of loans, the accrual of interest is discontinued when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about further collectability of principal or interest, even though the loan is currently performing. A loan may remain on accrual status if it is in the process of collection and is either guaranteed or well secured. When a loan is placed on nonaccrual status, unpaid interest credited to income in the current year is reversed and unpaid interest accrued in prior years is charged against the allowance for credit losses. Interest received on nonaccrual loans generally is either applied against the principal or reported as interest income on a cash basis, according to management’s judgment as to the collectability of principal. Generally, loans are restored to accrual status when the obligation is brought current, has performed in accordance with the contractual terms for a reasonable period of time, and the ultimate collectability of the total contractual principal and interest is no longer in doubt. The past-due status of all classes of loans is determined based on contractual due dates for loan payments.
Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block]	Allowance for Credit Losses ("ACL") – Loans The Bank adopted ASU 2016-13, effective January 1, 2023. Financial statement amounts related to loans recorded as of December 31, 2024 and 2023 are presented in accordance with the accounting policies described in the following sections. The guidance applies an expected-loss methodology, recognizing current expected credit losses for the remaining life of the asset at the time of origination or acquisition. The allowance for credit losses ("ACL") is a valuation reserve established and maintained by charges against income and is deducted from the amortized cost basis of loans to present the net amount expected to be collected on the loans. Loans, or portions thereof, are charged off against the ACL when they are deemed uncollectible. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged-off. The ACL is an estimate of expected credit losses, measured over the contractual life of a loan that considers our historical loss experience, current conditions, and forecasts of future economic conditions. Determination of an appropriate ACL is inherently subjective and may have significant changes from period to period. Management uses a discounted cash flow ("DCF") model to calculate the present value of the expected cash flows for pools of loans that share similar risk characteristics and compares the results of this calculation to the amortized cost basis to determine its ACL balance. The contractual term used in projecting the cash flows of a loan is based on the maturity date of a loan and is adjusted for prepayment or curtailment assumptions, which may shorten that contractual time period. Options to extend are considered by management in determining the contractual term. The key inputs to the DCF model are (1) probability of default, (2) loss given default, (3) prepayment and curtailment rates, (4) reasonable and supportable economic forecasts, (5) forecast reversion period, (6) expected recoveries on charged off loans, and (7) discount rate. Probability of Default ("PD") In order to incorporate economic factors into forecasting within the DCF model, management elected to use the Loss Driver method to generate the PD rate inputs. The Loss Driver method analyzes how one or more economic factors change the default rate using statistical regression analysis. Management selected economic factors that have strong correlations to historical default rates. Loss Given Default ("LGD") Management elected to use the Frye Jacobs parameter for determining the LGD input, which is an estimation technique that derives an LGD input from segment-specific risk curves that correlate LGD with PD. Prepayment and Curtailment Rates Prepayment Rates: Loan-level transaction data is used to calculate semi-annual prepayment rates. These semi-annual rates are annualized, and the average of the annualized rates is used in the DCF calculation for fixed payments or term loans. Rates are calculated for each pool. Curtailment Rates: Loan-level transaction data is used to calculate annual curtailment rates using available historical loan-level data. The average of the historical rates is used in the DCF model for interest-only payment or line-of-credit type loans. Rates are calculated for each pool. Reasonable and Supportable Forecasts The forecast data used in the DCF model is obtained via a subscription to a widely recognized and relied-upon company that publishes various forecast scenarios. Management evaluates the various scenarios to determine a reasonable and supportable scenario. Forecast Reversion Period Management uses forecasts to predict how economic factors will perform and has determined to use a four-quarter forecast period as well as an eight-quarter straight-line reversion period to historical averages (also commonly referred to as the mean reversion period). Expected Recoveries on Charged-off Loans Management performs an analysis to estimate recoveries that could be reasonably expected based on historical experience in order to account for expected recoveries on loans that have already been fully charged off and are not included in the ACL calculation. Discount Rate The effective interest rate of the underlying loans of the Company serves as the discount rate applied to the expected periodic cash flows. Management adjusts the effective interest rate used to discount expected cash flows to incorporate expected prepayments. Individual Evaluation Management evaluates individual instruments for expected credit losses when those instruments do not share similar risk characteristics with instruments evaluated using a collective (pooled) basis. These instruments will not be included in the collective analyses. The individual analysis will establish a specific reserve for instruments in scope. The allowance for credit losses is measured on a collective (pool) basis when similar risk characteristics exist. The Company’s loan portfolio is segmented to a level that allows management to monitor risk and performance. The portfolio is segmented into Commercial Real Estate (“CRE”), which is further segmented into Owner Occupied (“CRE OO”), Non-owner Occupied (“CRE NOO”), and Multifamily Residential, Residential Real Estate (“RRE”), Commercial and Industrial (“C&I”), Home Equity Lines of Credit (“HELOC”), Construction and Other (“Construction”), and Consumer Installment Loans. The CRE loan segments consist of loans made to finance the activities of CRE owners and operators and certain agricultural loans. The RRE and HELOC loan segments consist of loans made to finance the activities of residential homeowners. The C&I loan segment consists of loans made to finance the activities of commercial customers and certain agricultural loans. The consumer loan segment consists primarily of installment loans and overdraft lines of credit connected with customer deposit accounts. Historical credit loss experience is the basis for the estimation of expected credit losses. We apply historical loss rates to pools of loans with similar risk characteristics. After consideration of the historic loss calculation, management applies qualitative adjustments to reflect the current conditions and reasonable and supportable forecasts not already reflected in the historical loss information at the balance sheet date. The qualitative adjustments for current conditions are based upon national and local economic trends and conditions, levels of and trends in delinquency rates and nonaccrual loans, trends in volumes and terms of loans, effects of changes in lending policies, experience, ability, and depth of lending staff, the value of underlying collateral, concentrations of credit from a loan type, industry, and/or geographic standpoint. These modified historical loss rates are multiplied by the outstanding principal balance of each loan to calculate a required reserve. The Bank has elected to exclude accrued interest receivable from the measurement of its ACL. When a loan is placed on nonaccrual status, any outstanding accrued interest is reversed against interest income. Accrued interest receivable is included within accrued interest receivable and other assets on the Consolidated Balance Sheet. The ACL calculation for individual loans begins with the use of normal credit review procedures to identify whether a loan no longer shares similar risk characteristics with other pooled loans and should, therefore, be individually assessed. The Bank automatically considers all non-accrual loans greater than $250,000 for individual analysis. Additional identification of loans to be individually evaluated is accomplished through the Bank’s normal loan review, criticized asset review, and portfolio management processes. The Bank previously evaluated all commercial loans greater than $150,000 for individual analysis that met the following criteria: 1) when it is determined that foreclosure is probable, 2) substandard, doubtful, and nonperforming loans when repayment is expected to be provided substantially through the operation or sale of the collateral, and 3) when it is determined by management that a loan does not share similar risk characteristics with other loans. Specific reserves are established based on the following three acceptable methods for measuring the ACL: 1) the present value of expected future cash flows discounted at the loan’s original effective interest rate, 2) the loan’s observable market price, or 3) the fair value of the collateral when the loan is collateral dependent. Management considers a financial asset as collateral dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral, based on management's assessment as of the reporting date. Measurement of the expected credit losses on collateral-dependent loans is based on the fair value of the collateral, less any costs to sell. A specific reserve is established or a charge-off is taken if the fair value of the loan is less than the loan balance. Large groups of smaller-balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Bank does not separately identify individual residential real estate loans, home equity loans, and consumer loans for impairment disclosures. Allowance for Credit Losses on Off-Balance Sheet Credit Exposures The Bank adopted ASU No. 2016-13 effective January 1, 2023. The Bank estimates expected credit losses over the contractual period in which the Bank is exposed to credit risk via a contractual obligation to extend credit unless that obligation is unconditionally cancellable by the Bank. The allowance for credit losses on off-balance sheet credit exposures is included in "accrued interest payable and other liabilities" on the Consolidated Balance Sheet and adjusted through the provision for credit losses. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on commitments expected to be funded over its estimated life, consistent with the estimation process on the loan portfolio.
Stockholders' Equity, Policy [Policy Text Block]	Restricted Stock Common stock of the FHLB represents ownership in an institution that is wholly owned by other financial institutions. This equity security is accounted for at cost and classified with "accrued interest and other assets" in the Consolidated Balance Sheet. The FHLB of Cincinnati has reported profits for 2024 and 2023, remains in compliance with regulatory capital and liquidity requirements, and continues to pay dividends on the stock and make redemptions at the par value. Considering these factors, management concluded that the stock was not impaired on December 31, 2024, or 2023.
Mortgage Banking Activity [Policy Text Block]	Mortgage Banking Activities The Bank sells residential mortgage loans on a servicing retained basis. Servicing rights are initially recorded at fair value. The Bank measures servicing assets using the amortization method. Loan servicing rights are amortized in proportion to and throughout estimated net future servicing revenue. The expected period of the estimated net servicing income is partly based on the expected prepayment of the underlying mortgages. The unamortized balance of mortgage servicing rights is included in "accrued interest and other assets" on the Consolidated Balance Sheet. Servicing fee income is recorded for fees earned for servicing loans and included in "other income" in the Consolidated Income Statement. The fees are based on a contractual percentage of outstanding principal and are recorded as income when earned. The amortization of mortgage servicing rights is netted against loan servicing fee income. Late fees and ancillary fees related to loan servicing are not material. The Bank is servicing loans for others in the amount of $197.4 million and $210.3 million on December 31, 2024, and 2023, respectively.
Property, Plant and Equipment, Policy [Policy Text Block]	Premises and Equipment Land is carried at cost. Premises and equipment are stated at cost net of accumulated depreciation. Depreciation is computed on the straight-line method over the assets' estimated useful lives, which range from 3 to 20 years for furniture, fixtures, and equipment and 3 to 40 years for buildings and leasehold improvements. Expenditures for maintenance and repairs are charged against income as incurred. Costs of significant additions and improvements are capitalized.
Lessee, Leases [Policy Text Block]	Leases The Company has operating and financing leases for several branch locations and office space. Generally, the underlying lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company may also lease specific office equipment under operating leases. Many of our leases include both lease (e.g., minimum rent payments) and non-lease components (e.g., common-area or other maintenance costs). The Company accounts for each element separately based on the standalone price of each component. Operating and financing leases with lease terms of less than one year are excluded from our right-of-use assets and lease liabilities. Operating and financing lease expense are recognized in "occupancy expense" and "equipment expense" in the Consolidated Income Statement on a straight-line basis over the lease term. Most leases include one or more options to renew. The exercise of lease renewal options is typically at the sole discretion of management. It is based on whether the extension options are reasonably certain to be exercised after giving proper consideration to all facts and circumstances of the lease. If management determines that the Company is reasonably sure to exercise the extension option(s), the additional term is included in the calculation of the right-of-use asset and a lease liability. As most of our leases do not provide an implicit rate, we use the fully collateralized FHLB borrowing rate commensurate with the lease terms based on the information available at the lease commencement date in determining the present value of the lease payments.
Business Combinations Policy [Policy Text Block]	Business Combinations Business combinations are accounted for under the acquisition method of accounting. Acquired assets, including separately identifiable intangible assets, and assumed liabilities are recorded at their acquisition-date fair values. The excess of the cost of acquisition over the fair values is recognized as goodwill. During the measurement period, which cannot exceed one year from the acquisition date, changes to estimated fair values are recognized as an adjustment to goodwill. Certain transaction costs are expensed as incurred.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	Goodwill Goodwill represents the amount by which the cost of net assets acquired in a business combination exceeds their fair value. Goodwill is not amortized and is tested for impairment, at least annually as of October 1, or when indicators of impairment exist. We have elected to perform qualitative assessment for testing the impairment of goodwill. If we elect to bypass this qualitative assessment or conclude as a result of the qualitative assessment that it is more likely than not that the fair value is less than its carrying value, a quantitative impairment test will be performed. If the fair value is less than carrying value, an impairment charge is recorded for the difference.
Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]	Intangible Assets Intangible assets include core deposit intangibles, which measure the value of consumer demand and savings deposits acquired in business combinations accounted for as purchases. The core deposit intangibles are amortized over their expected useful lives, commonly ten years, on a straight-line basis. The recoverability of the carrying value of intangible assets is evaluated on an ongoing basis, and permanent declines in value, if any, are charged to expense.
Life Insurance Corporate or Bank Owned [Policy Text Block]	Bank-Owned Life Insurance (“BOLI”) The Company owns insurance on the lives of a specific group of key employees. The policies were purchased to help offset the increase in the costs of various fringe benefit plans, including healthcare. The cash surrender value of these policies is included as an asset on the Consolidated Balance Sheet, and any increases in the cash surrender value are recorded as noninterest income on the Consolidated Income Statement. In the event of the death of an insured individual under these policies, the Company would receive a death benefit, which would be recorded as tax-free noninterest income.
Real Estate, Policy [Policy Text Block]	Other Real Estate Owned (“OREO”) Real estate properties acquired through foreclosure are initially recorded at fair value at the foreclosure date, establishing a new cost basis. After foreclosure, the real estate is carried at the lower of cost or fair value less estimated cost to sell. Revenue and expenses from operations of the properties, gains or losses on sales, and additions to the valuation allowance are included in operating results. At December 31, 2024 and 2023, the Company reported $352,000 and $228,000, respectively, in residential real estate loans in the process of foreclosure.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value Fair value is defined as the price to sell an asset or transfer a liability in an orderly transaction between market participants in the principal market. It represents an exit price at the measurement date. Valuation inputs can be observable or unobservable. All inputs, whether observable or unobservable, are ranked in accordance with a prescribed fair value hierarchy that gives the highest ranking to quoted prices in active markets for identification assets or liabilities (Level 1) and the lowest ranking to unobservable inputs (Level 3). Fair values for Level 2 assets and liabilities are based on a combination of one or more of the following factors: (1) quoted market prices for similar assets or liabilities, (2) observable inputs, such as interest rates or yield curves, or (3) inputs derived principally from or corroborated by observable market data. The level in the fair value hierarchy assigned to a fair value measurement is based on the lowest level input that is significant to the measurement. Assets and liabilities may transfer between levels based on the observable and unobservable inputs used at the valuation date. Assets and liabilities are recorded at fair value on a recurring or nonrecurring basis. Nonrecurring fair value adjustments are typically recorded with the application of lower of cost or fair value accounting or impairment.
Income Tax, Policy [Policy Text Block]	Income Taxes The Company and its subsidiaries file a consolidated federal income tax return. Deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. The net balance of deferred tax assets and liabilities is reported in "accrued interest receive and other assets" or "accrued interest payable and other liabilities" in the Consolidated Balance Sheet, as appropriate. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes.
Revenue from Contract with Customer [Policy Text Block]	Fee-based Services Revenue Recognition Refer to Note 2 - Revenue Recognition.
Share-Based Payment Arrangement [Policy Text Block]	Stock-Based Compensation The Company accounts for stock-based compensation based on the grant date fair value of all share-based payment awards expected to vest, including employee share options. Compensation cost is recognized for restricted stock issued to employees based on the fair value of these awards at the grant date. The market price of the Company’s common shares at the grant date is used to estimate the fair value of restricted stock and stock awards. Stock-based compensation cost for awards granted to employees is recognized over the required service period, generally defined as the vesting period, and is recorded in "salaries and employee benefits" expense in the Consolidated Income Statement, while the expense related to awards granted to directors is recorded in "other expense". (See Note 14 - Employee Benefits). One of the Company’s restricted stock plans allows for a portion of the value to be received in cash by the participant upon vesting. Therefore, the Company records the expense as a liability until the shares vest and the split of the payment between shares and cash can be determined. The Company also measures the fair value of the liability each reporting period and adjusts accordingly. Another of the Company's restricted stock plans settles in shares upon vesting, and the related expense is recorded through additional paid-in capital. The Company has performance-based restricted stock units whereby the vesting in the granted awards is contingent on certain internal and external financial performance factors. The fair value of these stock units is estimated using a Monte Carlo simulation, as further discussed in Note 14 - Employee Benefits.
Advertising Cost [Policy Text Block]	Advertising Costs Advertising costs are expensed as incurred.
Treasury Stock [Policy Text Block]	Treasury Stock When shares recognized as equity are repurchased, the amount of the consideration paid, which includes directly attributable costs, is recognized as a deduction from equity. Repurchased shares are classified as treasury shares and are presented in the treasury share reserve. The reserve for the Company’s treasury shares comprises the cost of the Company’s shares held by the Company.
Earnings Per Share, Policy [Policy Text Block]	Earnings Per Share The Company provides a dual presentation of basic and diluted earnings per share. Basic earnings per share is calculated utilizing net income as reported in the numerator and average shares outstanding in the denominator. The computation of diluted earnings per share differs in that the dilutive effects of any stock options, warrants, and convertible securities are adjusted in the denominator. Earnings and dividends per share are restated for all stock splits and stock dividends through the date of issuance of the financial statements.
Reclassification, Comparability Adjustment [Policy Text Block]	Reclassification of Comparative Amounts Certain comparative amounts for prior years have been reclassified to conform to current-year presentations. Such reclassifications did not affect net income or retained earnings.
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Pronouncements Adopted in 2024 In March 2023, the FASB issued ASU 2023-02, Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method. The amendments allow entities to elect to account for qualifying tax equity investments using the proportional amortization method, regardless of the program giving rise to the related tax credits. This method of accounting had been available only for qualifying investments in qualified affordable housing projects. The guidance also requires certain disclosures regarding an entity’s tax equity investments. The amendments in this ASU are effective for all entities for fiscal years beginning after December 15, 2023. This ASU did not have a significant impact on the Company’s financial statements. In January 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting, March 2020, to provide temporary optional expedients and exceptions to the U.S. GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens of the expected market transition from LIBOR and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (SOFR). Entities can elect not to apply certain modification accounting requirements to contracts affected by what the guidance calls “reference rate reform” if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Also, entities can elect various optional expedients that would allow them to continue applying hedge accounting for hedging relationships affected by reference rate reform if certain criteria are met, and can make a one-time election to sell and/or reclassify held-to-maturity debt securities that reference an interest rate affected by reference rate reform. ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848 Issued December 2022, which was issued in December 2022, extended the period of time entities can utilize the reference rate reform relief guidance under ASU 2020-04 from December 31, 2022 to December 31, 2024. The ASUs did not have a significant impact on the Company’s financial statements. In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The amendment clarifies that a contractual restriction on the sale of an equity security is not considered part of the unit account of the equity security and is not considered in measuring its fair value. The ASU clarifies that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction. The ASU also requires certain disclosures for equity securities subject to contractual sale restrictions. The amendments in this ASU are effective for all entities for fiscal years beginning after December 15, 2023. This ASU did not have a significant impact on the Company’s financial statements. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. The ASU requires enhanced disclosures about significant segment expenses for public entities reporting segment information under ASC Topic 280. The amendments include required disclosure of significant segment expenses regularly reviewed by the chief operating decision maker, description of the composition of other segment items, and title and position of the chief operating decision maker. Additionally, the ASU requires public entities to provide all annual disclosures under Topic 280 in interim periods. The ASU also requires that public entities with a single reportable segment provide all the disclosures required by this amendment and existing disclosure requirements in Topic 820. The amendments in this ASU are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. The Company has a single reportable segment. The disclosure requirements under the ASU have been incorporated in Note 19 - Segment Reporting. Recent Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. The amendments require entities to disclose specific categories in the rate reconciliation and provide additional information for material reconciling items. The ASU also requires the disclosure of income taxes paid disaggregated by jurisdiction. The amendments in this ASU are effective for public business entities for annual periods beginning after December 15, 2024. This ASU is not expected to have a significant impact on the Company’s financial statements. In November 2024, the FASB issued ASU 2024-03, Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Topic 220-40): Disaggregation of Income Statement Expenses. The guidance requires public companies to disclose additional information about certain types of costs and expenses. The amendment should be applied on a prospective or retrospective basis. The amendments in this ASU are effective for annual periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027. This ASU is not expected to have a significant impact on the Company’s financial statements.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2024

Basis of Accounting, Policy [Policy Text Block]

Principles of Consolidation and Basis of Presentation

The consolidated financial statements of Middlefield Banc Corp. ("Company") include its bank subsidiary, The Middlefield Banking Company (“MBC” or “Bank”), and a nonbank asset resolution subsidiary EMORECO, Inc. The consolidated financial statements also include the accounts of MBC’s subsidiaries, Middlefield Investments, Inc. (“MI”) and MB Insurance Services (“MIS”). All significant inter-company items have been eliminated.

On March 13, 2019, MBC established MI as an operating subsidiary to hold and manage an investment portfolio. On December 31, 2024, MI’s assets consist of a cash account, investments, and related accrued interest accounts. MI may only hold and manage investments and may not engage in any other activity without prior approval of the Ohio Division of Financial Institutions. In the first quarter of 2022, MBC established MIS as an operating subsidiary to offer retail and business customers various insurance services, including home, renters, automobile, pet, identity theft, travel, and professional liability insurance. On December 31, 2024, MIS assets consist of a cash account, a prepaid asset, and an accounts receivable. As a result of the bank merger of Liberty National Bank and MBC on December 1, 2022, Middlefield Banc Corp. acquired a 100% ownership interest in LBSI Insurance, LLC (“LBSI”), a wholly owned financial subsidiary of Liberty National Bank. LBSI did not operate after the merger, and its existence ended January 19, 2024. All significant intercompany items have been eliminated between MBC and these subsidiaries.

On December 1, 2022, the Company completed its merger with Liberty Bancshares, Inc. (“Liberty’), pursuant to a previously announced definitive merger agreement. Under the terms of the merger agreement, Liberty shareholders received 2.752 shares of the Company’s common stock in exchange for each share of Liberty common stock they owned immediately before the merger. The Company issued 2,561,513 shares of its common stock in the merger, and the aggregate merger consideration was approximately $73.3 million. Upon closing, Liberty’s bank subsidiary was merged into MBC, and Liberty’s six full-service bank offices, in Ada and Kenton in Hardin County, Bellefontaine North and Bellefontaine South in Logan County, Marysville in Union County, and Westerville in Franklin County, became offices of MBC.

Use of Estimates, Policy [Policy Text Block]

Estimates

In preparing the financial statements, management is required to make estimates and assumptions that affect the reported amounts and liabilities as of the balance sheet date and revenues and expenses for the period. Actual results could differ from those estimates.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

The Company has defined cash and cash equivalents as those amounts included in the Consolidated Balance Sheet captions as “Cash and due from banks” and “Federal funds sold” with original maturities of less than 90 days.

Equity Method Investments [Policy Text Block]

Investments

Management determines the appropriate classification of investment securities at the time of purchase and re-evaluates such designation as of each balance sheet date.

Investment securities classified as available for sale are those securities that the Bank intends to hold for an indefinite period of time but not necessarily to maturity. Securities available for sale are carried at fair value. Any decision to sell a security classified as available for sale would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Bank’s assets and liabilities, liquidity needs, regulatory capital considerations, and other similar factors. Unrealized gains or losses are reported as increases or decreases in other comprehensive income (loss), net of the deferred tax effect. Realized gains or losses, determined on the basis of the cost of the specific securities sold, are included in earnings. Premiums and discounts are recognized in interest income using the interest method over the terms of the securities.

Investment securities classified as held to maturity are those securities the Bank has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or changes in general economic conditions. These securities are carried at cost, adjusted for the amortization of premium and accretion of discount, and computed by a method that approximates the interest method over the terms of the securities. As of December 31, 2024, the Company did not hold any held-to-maturity securities.

Equity securities, which are included in "other investments" on the Consolidated Balance Sheet, are measured at fair value with changes in fair value recognized in net income.

Marketable Securities, Policy [Policy Text Block]

Allowance for Credit Losses – Investment Securities Available for Sale

The Bank adopted ASU No. 2016-13, Financial Instruments - Credit Loses - Topic (326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), effective January 1, 2023. Financial statement amounts related to investment securities recorded as of December 31, 2024 and 2023 are presented in accordance with the accounting policies described in the following sections.

The Bank measures expected credit losses on available for sale investment securities when the Bank intends to sell, or when it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value through income. For available for sale investment securities that do not meet the aforementioned criteria, the Bank evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Bank considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this evaluation indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists, and an allowance for credit losses is recorded for the credit loss, equal to the amount that the fair value is less than the amortized cost basis. Economic forecast data is used to calculate the present value of expected cash flows. The Bank obtains its forecast data through a subscription to a widely recognized and relied-upon company that publishes various forecast scenarios. Management evaluates the various scenarios to determine a reasonable and supportable scenario and uses a single scenario in the model. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income.

The allowance for credit losses is included within "investment securities available for sale" on the Consolidated Balance Sheet, as applicable. Changes in the allowance for credit losses are recorded within the "provision for credit losses" on the Consolidated Income Statement. Losses are charged against the allowance when the Bank believes the collectability of an available for sale security is in jeopardy or when either of the criteria regarding intent or requirement to sell is met.

Accrued interest receivable on available for sale investment securities is included within "accrued interest receivable and other assets" on the Consolidated Balance Sheet. This amount is excluded from the estimate of expected credit losses. Available for sale investment securities are typically classified as nonaccrual when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about the further collectability of principal or interest. When available for sale investment securities are placed on nonaccrual status, unpaid interest credited to income is reversed.

Financing Receivable [Policy Text Block]

Loans

Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are stated at their outstanding unpaid principal balances, net of unearned income, which includes net deferred loan fees and costs and unamortized premiums and discounts. Accrued interest receivable is included within "accrued interest receivable and other assets" on the Consolidated Balance Sheet. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loans’ yield (interest income). The Bank amortizes these amounts over the contractual life of the loan. Premiums and discounts on purchased loans are amortized as adjustments to interest income using the effective yield method. Interest income is primarily recognized on an accrual basis according to formulas in written contracts, such as loan agreements.

The loan portfolio is segmented into commercial and consumer loans. Commercial loans consist of the following classes: commercial construction, commercial and industrial loans, and commercial real estate loans. Consumer loans consist of the following classes: residential real estate loans, home equity loans, and consumer loans.

For all classes of loans, the accrual of interest is discontinued when the contractual payment of principal or interest has become 90 days past due or management has serious doubts about further collectability of principal or interest, even though the loan is currently performing. A loan may remain on accrual status if it is in the process of collection and is either guaranteed or well secured. When a loan is placed on nonaccrual status, unpaid interest credited to income in the current year is reversed and unpaid interest accrued in prior years is charged against the allowance for credit losses. Interest received on nonaccrual loans generally is either applied against the principal or reported as interest income on a cash basis, according to management’s judgment as to the collectability of principal. Generally, loans are restored to accrual status when the obligation is brought current, has performed in accordance with the contractual terms for a reasonable period of time, and the ultimate collectability of the total contractual principal and interest is no longer in doubt. The past-due status of all classes of loans is determined based on contractual due dates for loan payments.

Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block]

Allowance for Credit Losses ("ACL") – Loans

The Bank adopted ASU 2016-13, effective January 1, 2023. Financial statement amounts related to loans recorded as of December 31, 2024 and 2023 are presented in accordance with the accounting policies described in the following sections. The guidance applies an expected-loss methodology, recognizing current expected credit losses for the remaining life of the asset at the time of origination or acquisition.

The allowance for credit losses ("ACL") is a valuation reserve established and maintained by charges against income and is deducted from the amortized cost basis of loans to present the net amount expected to be collected on the loans. Loans, or portions thereof, are charged off against the ACL when they are deemed uncollectible. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged-off.

The ACL is an estimate of expected credit losses, measured over the contractual life of a loan that considers our historical loss experience, current conditions, and forecasts of future economic conditions. Determination of an appropriate ACL is inherently subjective and may have significant changes from period to period.

Management uses a discounted cash flow ("DCF") model to calculate the present value of the expected cash flows for pools of loans that share similar risk characteristics and compares the results of this calculation to the amortized cost basis to determine its ACL balance.

The contractual term used in projecting the cash flows of a loan is based on the maturity date of a loan and is adjusted for prepayment or curtailment assumptions, which may shorten that contractual time period. Options to extend are considered by management in determining the contractual term.

The key inputs to the DCF model are (1) probability of default, (2) loss given default, (3) prepayment and curtailment rates, (4) reasonable and supportable economic forecasts, (5) forecast reversion period, (6) expected recoveries on charged off loans, and (7) discount rate.

Probability of Default ("PD")

In order to incorporate economic factors into forecasting within the DCF model, management elected to use the Loss Driver method to generate the PD rate inputs. The Loss Driver method analyzes how one or more economic factors change the default rate using statistical regression analysis. Management selected economic factors that have strong correlations to historical default rates.

Loss Given Default ("LGD")

Management elected to use the Frye Jacobs parameter for determining the LGD input, which is an estimation technique that derives an LGD input from segment-specific risk curves that correlate LGD with PD.

Prepayment and Curtailment Rates

Prepayment Rates: Loan-level transaction data is used to calculate semi-annual prepayment rates. These semi-annual rates are annualized, and the average of the annualized rates is used in the DCF calculation for fixed payments or term loans. Rates are calculated for each pool.

Curtailment Rates: Loan-level transaction data is used to calculate annual curtailment rates using available historical loan-level data. The average of the historical rates is used in the DCF model for interest-only payment or line-of-credit type loans. Rates are calculated for each pool.

Reasonable and Supportable Forecasts

The forecast data used in the DCF model is obtained via a subscription to a widely recognized and relied-upon company that publishes various forecast scenarios. Management evaluates the various scenarios to determine a reasonable and supportable scenario.

Forecast Reversion Period

Management uses forecasts to predict how economic factors will perform and has determined to use a four-quarter forecast period as well as an eight-quarter straight-line reversion period to historical averages (also commonly referred to as the mean reversion period).

Expected Recoveries on Charged-off Loans

Management performs an analysis to estimate recoveries that could be reasonably expected based on historical experience in order to account for expected recoveries on loans that have already been fully charged off and are not included in the ACL calculation.

Discount Rate

The effective interest rate of the underlying loans of the Company serves as the discount rate applied to the expected periodic cash flows. Management adjusts the effective interest rate used to discount expected cash flows to incorporate expected prepayments.

Individual Evaluation

Management evaluates individual instruments for expected credit losses when those instruments do not share similar risk characteristics with instruments evaluated using a collective (pooled) basis. These instruments will not be included in the collective analyses. The individual analysis will establish a specific reserve for instruments in scope.

The allowance for credit losses is measured on a collective (pool) basis when similar risk characteristics exist. The Company’s loan portfolio is segmented to a level that allows management to monitor risk and performance. The portfolio is segmented into Commercial Real Estate (“CRE”), which is further segmented into Owner Occupied (“CRE OO”), Non-owner Occupied (“CRE NOO”), and Multifamily Residential, Residential Real Estate (“RRE”), Commercial and Industrial (“C&I”), Home Equity Lines of Credit (“HELOC”), Construction and Other (“Construction”), and Consumer Installment Loans. The CRE loan segments consist of loans made to finance the activities of CRE owners and operators and certain agricultural loans. The RRE and HELOC loan segments consist of loans made to finance the activities of residential homeowners. The C&I loan segment consists of loans made to finance the activities of commercial customers and certain agricultural loans. The consumer loan segment consists primarily of installment loans and overdraft lines of credit connected with customer deposit accounts.

Historical credit loss experience is the basis for the estimation of expected credit losses. We apply historical loss rates to pools of loans with similar risk characteristics. After consideration of the historic loss calculation, management applies qualitative adjustments to reflect the current conditions and reasonable and supportable forecasts not already reflected in the historical loss information at the balance sheet date. The qualitative adjustments for current conditions are based upon national and local economic trends and conditions, levels of and trends in delinquency rates and nonaccrual loans, trends in volumes and terms of loans, effects of changes in lending policies, experience, ability, and depth of lending staff, the value of underlying collateral, concentrations of credit from a loan type, industry, and/or geographic standpoint. These modified historical loss rates are multiplied by the outstanding principal balance of each loan to calculate a required reserve.

The Bank has elected to exclude accrued interest receivable from the measurement of its ACL. When a loan is placed on nonaccrual status, any outstanding accrued interest is reversed against interest income. Accrued interest receivable is included within accrued interest receivable and other assets on the Consolidated Balance Sheet.

The ACL calculation for individual loans begins with the use of normal credit review procedures to identify whether a loan no longer shares similar risk characteristics with other pooled loans and should, therefore, be individually assessed. The Bank automatically considers all non-accrual loans greater than $250,000 for individual analysis. Additional identification of loans to be individually evaluated is accomplished through the Bank’s normal loan review, criticized asset review, and portfolio management processes. The Bank previously evaluated all commercial loans greater than $150,000 for individual analysis that met the following criteria: 1) when it is determined that foreclosure is probable, 2) substandard, doubtful, and nonperforming loans when repayment is expected to be provided substantially through the operation or sale of the collateral, and 3) when it is determined by management that a loan does not share similar risk characteristics with other loans. Specific reserves are established based on the following three acceptable methods for measuring the ACL: 1) the present value of expected future cash flows discounted at the loan’s original effective interest rate, 2) the loan’s observable market price, or 3) the fair value of the collateral when the loan is collateral dependent. Management considers a financial asset as collateral dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral, based on management's assessment as of the reporting date. Measurement of the expected credit losses on collateral-dependent loans is based on the fair value of the collateral, less any costs to sell. A specific reserve is established or a charge-off is taken if the fair value of the loan is less than the loan balance. Large groups of smaller-balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Bank does not separately identify individual residential real estate loans, home equity loans, and consumer loans for impairment disclosures.

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures

The Bank adopted ASU No. 2016-13 effective January 1, 2023. The Bank estimates expected credit losses over the contractual period in which the Bank is exposed to credit risk via a contractual obligation to extend credit unless that obligation is unconditionally cancellable by the Bank. The allowance for credit losses on off-balance sheet credit exposures is included in "accrued interest payable and other liabilities" on the Consolidated Balance Sheet and adjusted through the provision for credit losses. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on commitments expected to be funded over its estimated life, consistent with the estimation process on the loan portfolio.

Stockholders' Equity, Policy [Policy Text Block]

Restricted Stock

Common stock of the FHLB represents ownership in an institution that is wholly owned by other financial institutions. This equity security is accounted for at cost and classified with "accrued interest and other assets" in the Consolidated Balance Sheet. The FHLB of Cincinnati has reported profits for 2024 and 2023, remains in compliance with regulatory capital and liquidity requirements, and continues to pay dividends on the stock and make redemptions at the par value. Considering these factors, management concluded that the stock was not impaired on December 31, 2024, or 2023.

Mortgage Banking Activity [Policy Text Block]

Mortgage Banking Activities

The Bank sells residential mortgage loans on a servicing retained basis. Servicing rights are initially recorded at fair value. The Bank measures servicing assets using the amortization method. Loan servicing rights are amortized in proportion to and throughout estimated net future servicing revenue. The expected period of the estimated net servicing income is partly based on the expected prepayment of the underlying mortgages. The unamortized balance of mortgage servicing rights is included in "accrued interest and other assets" on the Consolidated Balance Sheet.

Servicing fee income is recorded for fees earned for servicing loans and included in "other income" in the Consolidated Income Statement. The fees are based on a contractual percentage of outstanding principal and are recorded as income when earned. The amortization of mortgage servicing rights is netted against loan servicing fee income. Late fees and ancillary fees related to loan servicing are not material. The Bank is servicing loans for others in the amount of $197.4 million and $210.3 million on December 31, 2024, and 2023, respectively.

Property, Plant and Equipment, Policy [Policy Text Block]

Premises and Equipment

Land is carried at cost. Premises and equipment are stated at cost net of accumulated depreciation. Depreciation is computed on the straight-line method over the assets' estimated useful lives, which range from 3 to 20 years for furniture, fixtures, and equipment and 3 to 40 years for buildings and leasehold improvements. Expenditures for maintenance and repairs are charged against income as incurred. Costs of significant additions and improvements are capitalized.

Lessee, Leases [Policy Text Block]

Leases

The Company has operating and financing leases for several branch locations and office space. Generally, the underlying lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company may also lease specific office equipment under operating leases. Many of our leases include both lease (e.g., minimum rent payments) and non-lease components (e.g., common-area or other maintenance costs). The Company accounts for each element separately based on the standalone price of each component. Operating and financing leases with lease terms of less than one year are excluded from our right-of-use assets and lease liabilities. Operating and financing lease expense are recognized in "occupancy expense" and "equipment expense" in the Consolidated Income Statement on a straight-line basis over the lease term.

Most leases include one or more options to renew. The exercise of lease renewal options is typically at the sole discretion of management. It is based on whether the extension options are reasonably certain to be exercised after giving proper consideration to all facts and circumstances of the lease. If management determines that the Company is reasonably sure to exercise the extension option(s), the additional term is included in the calculation of the right-of-use asset and a lease liability.

As most of our leases do not provide an implicit rate, we use the fully collateralized FHLB borrowing rate commensurate with the lease terms based on the information available at the lease commencement date in determining the present value of the lease payments.

Business Combinations Policy [Policy Text Block]

Business Combinations

Business combinations are accounted for under the acquisition method of accounting. Acquired assets, including separately identifiable intangible assets, and assumed liabilities are recorded at their acquisition-date fair values. The excess of the cost of acquisition over the fair values is recognized as goodwill. During the measurement period, which cannot exceed one year from the acquisition date, changes to estimated fair values are recognized as an adjustment to goodwill. Certain transaction costs are expensed as incurred.

Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]

Goodwill

Goodwill represents the amount by which the cost of net assets acquired in a business combination exceeds their fair value. Goodwill is not amortized and is tested for impairment, at least annually as of October 1, or when indicators of impairment exist. We have elected to perform qualitative assessment for testing the impairment of goodwill. If we elect to bypass this qualitative assessment or conclude as a result of the qualitative assessment that it is more likely than not that the fair value is less than its carrying value, a quantitative impairment test will be performed. If the fair value is less than carrying value, an impairment charge is recorded for the difference.

Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]

Intangible Assets

Intangible assets include core deposit intangibles, which measure the value of consumer demand and savings deposits acquired in business combinations accounted for as purchases. The core deposit intangibles are amortized over their expected useful lives, commonly ten years, on a straight-line basis. The recoverability of the carrying value of intangible assets is evaluated on an ongoing basis, and permanent declines in value, if any, are charged to expense.

Life Insurance Corporate or Bank Owned [Policy Text Block]

Bank-Owned Life Insurance (“BOLI”)

The Company owns insurance on the lives of a specific group of key employees. The policies were purchased to help offset the increase in the costs of various fringe benefit plans, including healthcare. The cash surrender value of these policies is included as an asset on the Consolidated Balance Sheet, and any increases in the cash surrender value are recorded as noninterest income on the Consolidated Income Statement. In the event of the death of an insured individual under these policies, the Company would receive a death benefit, which would be recorded as tax-free noninterest income.

Real Estate, Policy [Policy Text Block]

Other Real Estate Owned (“OREO”)

Real estate properties acquired through foreclosure are initially recorded at fair value at the foreclosure date, establishing a new cost basis. After foreclosure, the real estate is carried at the lower of cost or fair value less estimated cost to sell. Revenue and expenses from operations of the properties, gains or losses on sales, and additions to the valuation allowance are included in operating results. At December 31, 2024 and 2023, the Company reported $352,000 and $228,000, respectively, in residential real estate loans in the process of foreclosure.

Fair Value Measurement, Policy [Policy Text Block]

Fair Value

Fair value is defined as the price to sell an asset or transfer a liability in an orderly transaction between market participants in the principal market. It represents an exit price at the measurement date. Valuation inputs can be observable or unobservable. All inputs, whether observable or unobservable, are ranked in accordance with a prescribed fair value hierarchy that gives the highest ranking to quoted prices in active markets for identification assets or liabilities (Level 1) and the lowest ranking to unobservable inputs (Level 3). Fair values for Level 2 assets and liabilities are based on a combination of one or more of the following factors: (1) quoted market prices for similar assets or liabilities, (2) observable inputs, such as interest rates or yield curves, or (3) inputs derived principally from or corroborated by observable market data. The level in the fair value hierarchy assigned to a fair value measurement is based on the lowest level input that is significant to the measurement. Assets and liabilities may transfer between levels based on the observable and unobservable inputs used at the valuation date.

Assets and liabilities are recorded at fair value on a recurring or nonrecurring basis. Nonrecurring fair value adjustments are typically recorded with the application of lower of cost or fair value accounting or impairment.

Income Tax, Policy [Policy Text Block]

Income Taxes

The Company and its subsidiaries file a consolidated federal income tax return. Deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. The net balance of deferred tax assets and liabilities is reported in "accrued interest receive and other assets" or "accrued interest payable and other liabilities" in the Consolidated Balance Sheet, as appropriate. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes.

Revenue from Contract with Customer [Policy Text Block]

Fee-based Services Revenue Recognition

Refer to Note 2 - Revenue Recognition.

Share-Based Payment Arrangement [Policy Text Block]

Stock-Based Compensation

The Company accounts for stock-based compensation based on the grant date fair value of all share-based payment awards expected to vest, including employee share options. Compensation cost is recognized for restricted stock issued to employees based on the fair value of these awards at the grant date. The market price of the Company’s common shares at the grant date is used to estimate the fair value of restricted stock and stock awards. Stock-based compensation cost for awards granted to employees is recognized over the required service period, generally defined as the vesting period, and is recorded in "salaries and employee benefits" expense in the Consolidated Income Statement, while the expense related to awards granted to directors is recorded in "other expense". (See Note 14 - Employee Benefits). One of the Company’s restricted stock plans allows for a portion of the value to be received in cash by the participant upon vesting. Therefore, the Company records the expense as a liability until the shares vest and the split of the payment between shares and cash can be determined. The Company also measures the fair value of the liability each reporting period and adjusts accordingly. Another of the Company's restricted stock plans settles in shares upon vesting, and the related expense is recorded through additional paid-in capital.

The Company has performance-based restricted stock units whereby the vesting in the granted awards is contingent on certain internal and external financial performance factors. The fair value of these stock units is estimated using a Monte Carlo simulation, as further discussed in Note 14 - Employee Benefits.

Advertising Cost [Policy Text Block]

Advertising Costs

Advertising costs are expensed as incurred.

Treasury Stock [Policy Text Block]

Treasury Stock

When shares recognized as equity are repurchased, the amount of the consideration paid, which includes directly attributable costs, is recognized as a deduction from equity. Repurchased shares are classified as treasury shares and are presented in the treasury share reserve. The reserve for the Company’s treasury shares comprises the cost of the Company’s shares held by the Company.

Earnings Per Share, Policy [Policy Text Block]

Earnings Per Share

The Company provides a dual presentation of basic and diluted earnings per share. Basic earnings per share is calculated utilizing net income as reported in the numerator and average shares outstanding in the denominator. The computation of diluted earnings per share differs in that the dilutive effects of any stock options, warrants, and convertible securities are adjusted in the denominator. Earnings and dividends per share are restated for all stock splits and stock dividends through the date of issuance of the financial statements.

Reclassification, Comparability Adjustment [Policy Text Block]

Reclassification of Comparative Amounts

Certain comparative amounts for prior years have been reclassified to conform to current-year presentations. Such reclassifications did not affect net income or retained earnings.

New Accounting Pronouncements, Policy [Policy Text Block]

Accounting Pronouncements Adopted in 2024

In March 2023, the FASB issued ASU 2023-02, Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method. The amendments allow entities to elect to account for qualifying tax equity investments using the proportional amortization method, regardless of the program giving rise to the related tax credits. This method of accounting had been available only for qualifying investments in qualified affordable housing projects. The guidance also requires certain disclosures regarding an entity’s tax equity investments. The amendments in this ASU are effective for all entities for fiscal years beginning after December 15, 2023. This ASU did not have a significant impact on the Company’s financial statements.

In January 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting, March 2020, to provide temporary optional expedients and exceptions to the U.S. GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens of the expected market transition from LIBOR and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (SOFR). Entities can elect not to apply certain modification accounting requirements to contracts affected by what the guidance calls “reference rate reform” if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Also, entities can elect various optional expedients that would allow them to continue applying hedge accounting for hedging relationships affected by reference rate reform if certain criteria are met, and can make a one-time election to sell and/or reclassify held-to-maturity debt securities that reference an interest rate affected by reference rate reform. ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848 Issued December 2022, which was issued in December 2022, extended the period of time entities can utilize the reference rate reform relief guidance under ASU 2020-04 from December 31, 2022 to December 31, 2024. The ASUs did not have a significant impact on the Company’s financial statements.

In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The amendment clarifies that a contractual restriction on the sale of an equity security is not considered part of the unit account of the equity security and is not considered in measuring its fair value. The ASU clarifies that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction. The ASU also requires certain disclosures for equity securities subject to contractual sale restrictions. The amendments in this ASU are effective for all entities for fiscal years beginning after December 15, 2023. This ASU did not have a significant impact on the Company’s financial statements.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. The ASU requires enhanced disclosures about significant segment expenses for public entities reporting segment information under ASC Topic 280. The amendments include required disclosure of significant segment expenses regularly reviewed by the chief operating decision maker, description of the composition of other segment items, and title and position of the chief operating decision maker. Additionally, the ASU requires public entities to provide all annual disclosures under Topic 280 in interim periods. The ASU also requires that public entities with a single reportable segment provide all the disclosures required by this amendment and existing disclosure requirements in Topic 820. The amendments in this ASU are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. The Company has a single reportable segment. The disclosure requirements under the ASU have been incorporated in Note 19 - Segment Reporting.

Recent Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. The amendments require entities to disclose specific categories in the rate reconciliation and provide additional information for material reconciling items. The ASU also requires the disclosure of income taxes paid disaggregated by jurisdiction. The amendments in this ASU are effective for public business entities for annual periods beginning after December 15, 2024. This ASU is not expected to have a significant impact on the Company’s financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Topic 220-40): Disaggregation of Income Statement Expenses. The guidance requires public companies to disclose additional information about certain types of costs and expenses. The amendment should be applied on a prospective or retrospective basis. The amendments in this ASU are effective for annual periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027. This ASU is not expected to have a significant impact on the Company’s financial statements.