3.24.0.1 html 698 772 1 false 139 0 false 9 false false R1.htm 100000 - Document - Document and Entity Information Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 100010 - Statement - Consolidated Balance Sheets Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedBalanceSheets Consolidated Balance Sheets Statements 2 false false R3.htm 100020 - Statement - Consolidated Balance Sheets (Parenthetical) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParenthetical Consolidated Balance Sheets (Parenthetical) Statements 3 false false R4.htm 100040 - Statement - Consolidated Statements of Income Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedStatementsOfIncome Consolidated Statements of Income Statements 4 false false R5.htm 100050 - Statement - Consolidated Statements of Comprehensive Income (Loss) Sheet http://www.firstmid.com/20231231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeLoss Consolidated Statements of Comprehensive Income (Loss) Statements 5 false false R6.htm 100060 - Statement - Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) Sheet http://www.firstmid.com/20231231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeLossParenthetical Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) Statements 6 false false R7.htm 100070 - Statement - Consolidated Statements of Changes in Stockholders' Equity Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInStockholdersEquity Consolidated Statements of Changes in Stockholders' Equity Statements 7 false false R8.htm 100080 - Statement - Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInStockholdersEquityParenthetical Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) Statements 8 false false R9.htm 100090 - Statement - Consolidated Statements of Cash Flows Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_StatementConsolidatedStatementsOfCashFlows Consolidated Statements of Cash Flows Statements 9 false false R10.htm 995410 - Disclosure - Pay vs Performance Disclosure Sheet http://xbrl.sec.gov/ecd/role/PvpDisclosure Pay vs Performance Disclosure Notes 10 false false R11.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 11 false false R12.htm 995457 - Disclosure - Basis of Accounting and Consolidation Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidation Basis of Accounting and Consolidation Notes 12 false false R13.htm 995467 - Disclosure - Earnings Per Share Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureEarningsPerShare Earnings Per Share Notes 13 false false R14.htm 995477 - Disclosure - Cash and Due from Banks Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCashAndDueFromBanks Cash and Due from Banks Notes 14 false false R15.htm 995487 - Disclosure - Investment Securities Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecurities Investment Securities Notes 15 false false R16.htm 995497 - Disclosure - Loans and Allowance for Credit Losses Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLosses Loans and Allowance for Credit Losses Notes 16 false false R17.htm 995507 - Disclosure - Premises and Equipment, Net Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosurePremisesAndEquipmentNet Premises and Equipment, Net Notes 17 false false R18.htm 995517 - Disclosure - Goodwill and Intangible Assets Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssets Goodwill and Intangible Assets Notes 18 false false R19.htm 995527 - Disclosure - Deposits Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDeposits Deposits Notes 19 false false R20.htm 995537 - Disclosure - Repurchase Agreements and Other Borrowings Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowings Repurchase Agreements and Other Borrowings Notes 20 false false R21.htm 995547 - Disclosure - Regulatory Capital Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRegulatoryCapital Regulatory Capital Notes 21 false false R22.htm 995557 - Disclosure - Disclosures of Fair Values of Financial Instruments Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstruments Disclosures of Fair Values of Financial Instruments Notes 22 false false R23.htm 995567 - Disclosure - Deferred Compensation Plan Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDeferredCompensationPlan Deferred Compensation Plan Notes 23 false false R24.htm 995577 - Disclosure - Stock Incentive Plan Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlan Stock Incentive Plan Notes 24 false false R25.htm 995587 - Disclosure - Retirement Plans Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRetirementPlans Retirement Plans Notes 25 false false R26.htm 995597 - Disclosure - Income Taxes Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxes Income Taxes Notes 26 false false R27.htm 995607 - Disclosure - Dividend Restrictions Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDividendRestrictions Dividend Restrictions Notes 27 false false R28.htm 995617 - Disclosure - Commitments and Contingent Liabilities Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCommitmentsAndContingentLiabilities Commitments and Contingent Liabilities Notes 28 false false R29.htm 995627 - Disclosure - Related Party Transactions Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRelatedPartyTransactions Related Party Transactions Notes 29 false false R30.htm 995637 - Disclosure - Business Combinations Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinations Business Combinations Notes 30 false false R31.htm 995647 - Disclosure - Leases Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeases Leases Notes 31 false false R32.htm 995657 - Disclosure - Derivatives Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivatives Derivatives Notes 32 false false R33.htm 995667 - Disclosure - Parent Company Only Financial Statements Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureParentCompanyOnlyFinancialStatements Parent Company Only Financial Statements Notes 33 false false R34.htm 995687 - Disclosure - Basis of Accounting and Consolidation (Policies) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidationPolicies Basis of Accounting and Consolidation (Policies) Policies http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidation 34 false false R35.htm 995697 - Disclosure - Basis of Accounting and Consolidation (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidationTables Basis of Accounting and Consolidation (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidation 35 false false R36.htm 995707 - Disclosure - Earnings Per Share (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureEarningsPerShareTables Earnings Per Share (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureEarningsPerShare 36 false false R37.htm 995717 - Disclosure - Investment Securities (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesTables Investment Securities (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecurities 37 false false R38.htm 995727 - Disclosure - Loans and Allowance for Credit Losses (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesTables Loans and Allowance for Credit Losses (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLosses 38 false false R39.htm 995737 - Disclosure - Premises and Equipment, Net (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosurePremisesAndEquipmentNetTables Premises and Equipment, Net (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosurePremisesAndEquipmentNet 39 false false R40.htm 995747 - Disclosure - Goodwill and Intangible Assets (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsTables Goodwill and Intangible Assets (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssets 40 false false R41.htm 995757 - Disclosure - Deposits (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsTables Deposits (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDeposits 41 false false R42.htm 995767 - Disclosure - Repurchase Agreements and Other Borrowings (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsTables Repurchase Agreements and Other Borrowings (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowings 42 false false R43.htm 995777 - Disclosure - Regulatory Capital (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRegulatoryCapitalTables Regulatory Capital (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRegulatoryCapital 43 false false R44.htm 995787 - Disclosure - Disclosures of Fair Values of Financial Instruments (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsTables Disclosures of Fair Values of Financial Instruments (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstruments 44 false false R45.htm 995797 - Disclosure - Stock Incentive Plan (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlanTables Stock Incentive Plan (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlan 45 false false R46.htm 995807 - Disclosure - Income Taxes (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxesTables Income Taxes (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxes 46 false false R47.htm 995817 - Disclosure - Commitments and Contingent Liabilities (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCommitmentsAndContingentLiabilitiesTables Commitments and Contingent Liabilities (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCommitmentsAndContingentLiabilities 47 false false R48.htm 995827 - Disclosure - Related Party Transactions (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRelatedPartyTransactionsTables Related Party Transactions (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRelatedPartyTransactions 48 false false R49.htm 995837 - Disclosure - Business Combinations (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinationsTables Business Combinations (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinations 49 false false R50.htm 995847 - Disclosure - Leases (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeasesTables Leases (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeases 50 false false R51.htm 995857 - Disclosure - Derivatives (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivativesTables Derivatives (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivatives 51 false false R52.htm 995867 - Disclosure - Parent Company Only Financial Statements (Tables) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureParentCompanyOnlyFinancialStatementsTables Parent Company Only Financial Statements (Tables) Tables http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureParentCompanyOnlyFinancialStatements 52 false false R53.htm 995887 - Disclosure - Basis of Accounting and Consolidation - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBasisOfAccountingAndConsolidationAdditionalInformationDetails Basis of Accounting and Consolidation - Additional Information (Details) Details 53 false false R54.htm 995897 - Disclosure - Basis of Accounting and Consolidation - Summary of Estimated Useful Lives for Major Depreciable Classification of Premises and Equipment (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBasisOfAccountingAndConsolidationSummaryOfEstimatedUsefulLivesForMajorDepreciableClassificationOfPremisesAndEquipmentDetails Basis of Accounting and Consolidation - Summary of Estimated Useful Lives for Major Depreciable Classification of Premises and Equipment (Details) Details 54 false false R55.htm 995907 - Disclosure - Basis of Accounting and Consolidation - Schedule of Components of Accumulated Other Comprehensive Loss (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBasisOfAccountingAndConsolidationScheduleOfComponentsOfAccumulatedOtherComprehensiveLossDetails Basis of Accounting and Consolidation - Schedule of Components of Accumulated Other Comprehensive Loss (Details) Details 55 false false R56.htm 995917 - Disclosure - Basis of Accounting and Consolidation - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Loss (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBasisOfAccountingAndConsolidationScheduleOfAmountsReclassifiedFromAccumulatedOtherComprehensiveLossDetails Basis of Accounting and Consolidation - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Loss (Details) Details 56 false false R57.htm 995927 - Disclosure - Earnings Per Share - Components of Basic and Diluted Net Income Per Common Share (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureEarningsPerShareComponentsOfBasicAndDilutedNetIncomePerCommonShareDetails Earnings Per Share - Components of Basic and Diluted Net Income Per Common Share (Details) Details 57 false false R58.htm 995937 - Disclosure - Earnings Per Share - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureEarningsPerShareAdditionalInformationDetails Earnings Per Share - Additional Information (Details) Details 58 false false R59.htm 995947 - Disclosure - Cash and Due from Banks - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureCashAndDueFromBanksAdditionalInformationDetails Cash and Due from Banks - Additional Information (Details) Details 59 false false R60.htm 995957 - Disclosure - Investment Securities - Available for Sale and Held for Maturity Securities (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesAvailableForSaleAndHeldForMaturitySecuritiesDetails Investment Securities - Available for Sale and Held for Maturity Securities (Details) Details 60 false false R61.htm 995967 - Disclosure - Investment Securities - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesAdditionalInformationDetails Investment Securities - Additional Information (Details) Details 61 false false R62.htm 995977 - Disclosure - Investment Securities - Schedule of Proceeds From Sales of Available for Sale Investment Securities, Realized Gains and Losses and Income Tax Expense (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesScheduleOfProceedsFromSalesOfAvailableForSaleInvestmentSecuritiesRealizedGainsAndLossesAndIncomeTaxExpenseDetails Investment Securities - Schedule of Proceeds From Sales of Available for Sale Investment Securities, Realized Gains and Losses and Income Tax Expense (Details) Details 62 false false R63.htm 995987 - Disclosure - Investment Securities - Investments Classified by Contractual Maturity Date (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesInvestmentsClassifiedByContractualMaturityDateDetails Investment Securities - Investments Classified by Contractual Maturity Date (Details) Details 63 false false R64.htm 995997 - Disclosure - Investment Securities - Fair Value of Investments with Sustained Gross Unrealized Losses (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesFairValueOfInvestmentsWithSustainedGrossUnrealizedLossesDetails Investment Securities - Fair Value of Investments with Sustained Gross Unrealized Losses (Details) Details 64 false false R65.htm 996007 - Disclosure - Investment Securities - Maturities of Investment Securities (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureInvestmentSecuritiesMaturitiesOfInvestmentSecuritiesDetails Investment Securities - Maturities of Investment Securities (Details) Details 65 false false R66.htm 996017 - Disclosure - Loans and Allowance for Credit Losses - Summary of Loans (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesSummaryOfLoansDetails Loans and Allowance for Credit Losses - Summary of Loans (Details) Details 66 false false R67.htm 996027 - Disclosure - Loans and Allowance for Credit Losses - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesAdditionalInformationDetails Loans and Allowance for Credit Losses - Additional Information (Details) Details 67 false false R68.htm 996037 - Disclosure - Loans and Allowance for Credit Losses - Allowance for Credit Losses Based on Portfolio Segment (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesAllowanceForCreditLossesBasedOnPortfolioSegmentDetails Loans and Allowance for Credit Losses - Allowance for Credit Losses Based on Portfolio Segment (Details) Details 68 false false R69.htm 996047 - Disclosure - Loans and Allowance for Credit Losses - Amortized Cost Basis of Collateral-Dependent Loans by Class of Loans Individually Evaluated (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesAmortizedCostBasisOfCollateralDependentLoansByClassOfLoansIndividuallyEvaluatedDetails Loans and Allowance for Credit Losses - Amortized Cost Basis of Collateral-Dependent Loans by Class of Loans Individually Evaluated (Details) Details 69 false false R70.htm 996057 - Disclosure - Loans and Allowance for Credit Losses - Credit Risk Profile of Loan Portfolio Based on Risk Rating Category and Payment Activity (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesCreditRiskProfileOfLoanPortfolioBasedOnRiskRatingCategoryAndPaymentActivityDetails Loans and Allowance for Credit Losses - Credit Risk Profile of Loan Portfolio Based on Risk Rating Category and Payment Activity (Details) Details 70 false false R71.htm 996067 - Disclosure - Loans and Allowance for Credit Losses - Loan Portfolio Aging Analysis (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesLoanPortfolioAgingAnalysisDetails Loans and Allowance for Credit Losses - Loan Portfolio Aging Analysis (Details) Details 71 false false R72.htm 996077 - Disclosure - Loans and Allowance for Credit Losses - Recorded Balance of Loans on Nonaccrual Loans (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesRecordedBalanceOfLoansOnNonaccrualLoansDetails Loans and Allowance for Credit Losses - Recorded Balance of Loans on Nonaccrual Loans (Details) Details 72 false false R73.htm 996087 - Disclosure - Loans and Allowance for Credit Losses - Amortized Cost Basis of Loans Experiencing Difficulty and Modified (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesAmortizedCostBasisOfLoansExperiencingDifficultyAndModifiedDetails Loans and Allowance for Credit Losses - Amortized Cost Basis of Loans Experiencing Difficulty and Modified (Details) Details 73 false false R74.htm 996097 - Disclosure - Loans and Allowance for Credit Losses - Performance of Loans Modified (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesPerformanceOfLoansModifiedDetails Loans and Allowance for Credit Losses - Performance of Loans Modified (Details) Details 74 false false R75.htm 996107 - Disclosure - Loans and Allowance for Credit Losses - Financial Effect of Loan Modifications (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesFinancialEffectOfLoanModificationsDetails Loans and Allowance for Credit Losses - Financial Effect of Loan Modifications (Details) Details 75 false false R76.htm 996137 - Disclosure - Loans and Allowance for Credit Losses - Summary of Purchased Credit Deteriorated (PCD) Loans (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLoansAndAllowanceForCreditLossesSummaryOfPurchasedCreditDeterioratedPCDLoansDetails Loans and Allowance for Credit Losses - Summary of Purchased Credit Deteriorated (PCD) Loans (Details) Details 76 false false R77.htm 996147 - Disclosure - Premises and Equipment, Net - Summary of Premises and Equipment (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosurePremisesAndEquipmentNetSummaryOfPremisesAndEquipmentDetails Premises and Equipment, Net - Summary of Premises and Equipment (Details) Details 77 false false R78.htm 996157 - Disclosure - Premises and Equipment, Net - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosurePremisesAndEquipmentNetAdditionalInformationDetails Premises and Equipment, Net - Additional Information (Details) Details 78 false false R79.htm 996167 - Disclosure - Goodwill and Intangible Assets - Schedule of Intangible Assets and Goodwill (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfIntangibleAssetsAndGoodwillDetails Goodwill and Intangible Assets - Schedule of Intangible Assets and Goodwill (Details) Details 79 false false R80.htm 996177 - Disclosure - Goodwill and Intangible Assets - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails Goodwill and Intangible Assets - Additional Information (Details) Details 80 false false R81.htm 996187 - Disclosure - Goodwill and Intangible Assets - Schedule of Reconciliation of Purchase Price Paid for Acquisition and Goodwill Recorded (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfReconciliationOfPurchasePricePaidForAcquisitionAndGoodwillRecordedDetails Goodwill and Intangible Assets - Schedule of Reconciliation of Purchase Price Paid for Acquisition and Goodwill Recorded (Details) Details 81 false false R82.htm 996197 - Disclosure - Goodwill and Intangible Assets - Intangible Assets Mortgage Servicing Rights (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsIntangibleAssetsMortgageServicingRightsDetails Goodwill and Intangible Assets - Intangible Assets Mortgage Servicing Rights (Details) Details 82 false false R83.htm 996207 - Disclosure - Goodwill and Intangible Assets - Schedule of Intangible Assets Amortization Expense (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfIntangibleAssetsAmortizationExpenseDetails Goodwill and Intangible Assets - Schedule of Intangible Assets Amortization Expense (Details) Details 83 false false R84.htm 996217 - Disclosure - Goodwill and Intangible Assets - Schedule of Expected Amortization Expense (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfExpectedAmortizationExpenseDetails Goodwill and Intangible Assets - Schedule of Expected Amortization Expense (Details) Details 84 false false R85.htm 996227 - Disclosure - Deposits - Summary of Deposits (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsSummaryOfDepositsDetails Deposits - Summary of Deposits (Details) Details 85 false false R86.htm 996237 - Disclosure - Deposits - Summary of Interest Expense on Deposits (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsSummaryOfInterestExpenseOnDepositsDetails Deposits - Summary of Interest Expense on Deposits (Details) Details 86 false false R87.htm 996247 - Disclosure - Deposits - Summary of Aggregate Amount of Time Deposits more than 100,000 (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsSummaryOfAggregateAmountOfTimeDepositsMoreThan100000Details Deposits - Summary of Aggregate Amount of Time Deposits more than 100,000 (Details) Details 87 false false R88.htm 996257 - Disclosure - Deposits - Summary of Maturities for All Time Deposits (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsSummaryOfMaturitiesForAllTimeDepositsDetails Deposits - Summary of Maturities for All Time Deposits (Details) Details 88 false false R89.htm 996267 - Disclosure - Deposits - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDepositsAdditionalInformationDetails Deposits - Additional Information (Details) Details 89 false false R90.htm 996277 - Disclosure - Repurchase Agreements and Other Borrowings - Schedule of Borrowings (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsScheduleOfBorrowingsDetails Repurchase Agreements and Other Borrowings - Schedule of Borrowings (Details) Details 90 false false R91.htm 996287 - Disclosure - Repurchase Agreements and Other Borrowings - Schedule of Aggregate Annual Maturities of Long-Term Borrowings (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsScheduleOfAggregateAnnualMaturitiesOfLongTermBorrowingsDetails Repurchase Agreements and Other Borrowings - Schedule of Aggregate Annual Maturities of Long-Term Borrowings (Details) Details 91 false false R92.htm 996297 - Disclosure - Repurchase Agreements and Other Borrowings - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsAdditionalInformationDetails Repurchase Agreements and Other Borrowings - Additional Information (Details) Details 92 false false R93.htm 996307 - Disclosure - Repurchase Agreements and Other Borrowings - Federal Home Loan Bank, Advances (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsFederalHomeLoanBankAdvancesDetails Repurchase Agreements and Other Borrowings - Federal Home Loan Bank, Advances (Details) Details 93 false false R94.htm 996317 - Disclosure - Repurchase Agreements and Other Borrowings - Schedule of Securities Underlying the Repurchase Agreements (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsScheduleOfSecuritiesUnderlyingRepurchaseAgreementsDetails Repurchase Agreements and Other Borrowings - Schedule of Securities Underlying the Repurchase Agreements (Details) Details 94 false false R95.htm 996327 - Disclosure - Repurchase Agreements and Other Borrowings - Schedule of Securities Financing Transactions (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRepurchaseAgreementsAndOtherBorrowingsScheduleOfSecuritiesFinancingTransactionsDetails Repurchase Agreements and Other Borrowings - Schedule of Securities Financing Transactions (Details) Details 95 false false R96.htm 996337 - Disclosure - Regulatory Capital - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRegulatoryCapitalAdditionalInformationDetails Regulatory Capital - Additional Information (Details) Details 96 false false R97.htm 996347 - Disclosure - Regulatory Capital - Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRegulatoryCapitalScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsDetails Regulatory Capital - Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations (Details) Details 97 false false R98.htm 996357 - Disclosure - Disclosures of Fair Values of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails Disclosures of Fair Values of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) Details 98 false false R99.htm 996367 - Disclosure - Disclosures of Fair Values of Financial Instruments - Fair Value of Assets Measured on a Recurring Basis Using Significant Unobservable Inputs (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsFairValueOfAssetsMeasuredOnRecurringBasisUsingSignificantUnobservableInputsDetails Disclosures of Fair Values of Financial Instruments - Fair Value of Assets Measured on a Recurring Basis Using Significant Unobservable Inputs (Details) Details 99 false false R100.htm 996377 - Disclosure - Disclosures of Fair Values of Financial Instruments - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsAdditionalInformationDetails Disclosures of Fair Values of Financial Instruments - Additional Information (Details) Details 100 false false R101.htm 996387 - Disclosure - Disclosures of Fair Values of Financial Instruments - Assets Measured at Fair Value on a Nonrecurring Basis (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsAssetsMeasuredAtFairValueOnNonrecurringBasisDetails Disclosures of Fair Values of Financial Instruments - Assets Measured at Fair Value on a Nonrecurring Basis (Details) Details 101 false false R102.htm 996397 - Disclosure - Disclosures of Fair Values of Financial Instruments - Significant Unobservable Inputs Used in Valuation of Level 3 Fair Value Measurements (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsSignificantUnobservableInputsUsedInValuationOfLevel3FairValueMeasurementsDetails Disclosures of Fair Values of Financial Instruments - Significant Unobservable Inputs Used in Valuation of Level 3 Fair Value Measurements (Details) Details 102 false false R103.htm 996407 - Disclosure - Disclosures of Fair Values of Financial Instruments - Summary of Estimated Fair Values of Company Financial Instruments (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDisclosuresOfFairValuesOfFinancialInstrumentsSummaryOfEstimatedFairValuesOfCompanyFinancialInstrumentsDetails Disclosures of Fair Values of Financial Instruments - Summary of Estimated Fair Values of Company Financial Instruments (Details) Details 103 false false R104.htm 996417 - Disclosure - Deferred Compensation Plan - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDeferredCompensationPlanAdditionalInformationDetails Deferred Compensation Plan - Additional Information (Details) Details 104 false false R105.htm 996427 - Disclosure - Stock Incentive Plan - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlanAdditionalInformationDetails Stock Incentive Plan - Additional Information (Details) Details 105 false false R106.htm 996437 - Disclosure - Stock Incentive Plan - Summary of Compensation Cost, Net of Forfeitures, Related to Stock-based Compensation (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlanSummaryOfCompensationCostNetOfForfeituresRelatedToStockBasedCompensationDetails Stock Incentive Plan - Summary of Compensation Cost, Net of Forfeitures, Related to Stock-based Compensation (Details) Details 106 false false R107.htm 996447 - Disclosure - Stock Incentive Plan - Summary of Unvested Stock and Stock Units (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureStockIncentivePlanSummaryOfUnvestedStockAndStockUnitsDetails Stock Incentive Plan - Summary of Unvested Stock and Stock Units (Details) Details 107 false false R108.htm 996457 - Disclosure - Retirement Plans - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRetirementPlansAdditionalInformationDetails Retirement Plans - Additional Information (Details) Details 108 false false R109.htm 996467 - Disclosure - Income Taxes - Components of Federal and State Income Tax Expense (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxesComponentsOfFederalAndStateIncomeTaxExpenseDetails Income Taxes - Components of Federal and State Income Tax Expense (Details) Details 109 false false R110.htm 996477 - Disclosure - Income Taxes - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetails Income Taxes - Additional Information (Details) Details 110 false false R111.htm 996487 - Disclosure - Income Taxes - Effective Income Tax Reconciliation (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxesEffectiveIncomeTaxReconciliationDetails Income Taxes - Effective Income Tax Reconciliation (Details) Details 111 false false R112.htm 996497 - Disclosure - Income Taxes - Tax Effects of Temporary Differences on Deferred Tax Assets and Deferred Tax Liabilities (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureIncomeTaxesTaxEffectsOfTemporaryDifferencesOnDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails Income Taxes - Tax Effects of Temporary Differences on Deferred Tax Assets and Deferred Tax Liabilities (Details) Details 112 false false R113.htm 996507 - Disclosure - Dividend Restrictions - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDividendRestrictionsAdditionalInformationDetails Dividend Restrictions - Additional Information (Details) Details 113 false false R114.htm 996517 - Disclosure - Commitments and Contingent Liabilities - Schedule of Off-balance Sheet Financial Instruments Whose Contract Amounts Represent Credit Risk (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCommitmentsAndContingentLiabilitiesScheduleOfOffBalanceSheetFinancialInstrumentsWhoseContractAmountsRepresentCreditRiskDetails Commitments and Contingent Liabilities - Schedule of Off-balance Sheet Financial Instruments Whose Contract Amounts Represent Credit Risk (Details) Details 114 false false R115.htm 996527 - Disclosure - Commitments and Contingent Liabilities - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureCommitmentsAndContingentLiabilitiesAdditionalInformationDetails Commitments and Contingent Liabilities - Additional Information (Details) Details 115 false false R116.htm 996537 - Disclosure - Related Party Transactions - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails Related Party Transactions - Additional Information (Details) Details 116 false false R117.htm 996547 - Disclosure - Related Party Transactions - Schedule of Related Party Transactions (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureRelatedPartyTransactionsScheduleOfRelatedPartyTransactionsDetails Related Party Transactions - Schedule of Related Party Transactions (Details) Details 117 false false R118.htm 996557 - Disclosure - Business Combinations - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinationsAdditionalInformationDetails Business Combinations - Additional Information (Details) Details 118 false false R119.htm 996567 - Disclosure - Business Combinations - Estimated Fair Values of Assets Acquired and Liabilities Assumed (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinationsEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAssumedDetails Business Combinations - Estimated Fair Values of Assets Acquired and Liabilities Assumed (Details) Details 119 false false R120.htm 996577 - Disclosure - Business Combinations - Summary of Consideration Transferred (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBusinessCombinationsSummaryOfConsiderationTransferredDetails Business Combinations - Summary of Consideration Transferred (Details) Details 120 false false R121.htm 996587 - Disclosure - Business Combinations - Summary of Consideration Transferred (Parenthetical) (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBusinessCombinationsSummaryOfConsiderationTransferredParentheticalDetails Business Combinations - Summary of Consideration Transferred (Parenthetical) (Details) Details 121 false false R122.htm 996597 - Disclosure - Business Combinations - Summary of Purchased Credit Deteriorated (PCD) Loans (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureBusinessCombinationsSummaryOfPurchasedCreditDeterioratedPcdLoansDetails Business Combinations - Summary of Purchased Credit Deteriorated (PCD) Loans (Details) Details 122 false false R123.htm 996617 - Disclosure - Business Combinations - Unaudited Pro Forma Condensed Combined Financial Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureBusinessCombinationsUnauditedProFormaCondensedCombinedFinancialInformationDetails Business Combinations - Unaudited Pro Forma Condensed Combined Financial Information (Details) Details 123 false false R124.htm 996627 - Disclosure - Leases - Additional Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureLeasesAdditionalInformationDetails Leases - Additional Information (Details) Details 124 false false R125.htm 996637 - Disclosure - Leases - Summary of Supplemental Balance Sheet Information (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeasesSummaryOfSupplementalBalanceSheetInformationDetails Leases - Summary of Supplemental Balance Sheet Information (Details) Details 125 false false R126.htm 996647 - Disclosure - Leases - Summary of Future Minimum Lease Payments (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsDetails Leases - Summary of Future Minimum Lease Payments (Details) Details 126 false false R127.htm 996657 - Disclosure - Leases - Summary of Components of Lease Expense (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeasesSummaryOfComponentsOfLeaseExpenseDetails Leases - Summary of Components of Lease Expense (Details) Details 127 false false R128.htm 996667 - Disclosure - Leases - Summary of Operating Lease Cash Flows (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureLeasesSummaryOfOperatingLeaseCashFlowsDetails Leases - Summary of Operating Lease Cash Flows (Details) Details 128 false false R129.htm 996677 - Disclosure - Derivatives - Schedule of Derivative Instruments (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivativesScheduleOfDerivativeInstrumentsDetails Derivatives - Schedule of Derivative Instruments (Details) Details 129 false false R130.htm 996687 - Disclosure - Derivatives - Summary of Derivative Instruments, Gain (Loss) (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivativesSummaryOfDerivativeInstrumentsGainLossDetails Derivatives - Summary of Derivative Instruments, Gain (Loss) (Details) Details 130 false false R131.htm 996697 - Disclosure - Derivatives - Summary of Hedged Instrument (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivativesSummaryOfHedgedInstrumentDetails Derivatives - Summary of Hedged Instrument (Details) Details 131 false false R132.htm 996707 - Disclosure - Derivatives - Summary of Non Hedge Instruments (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureDerivativesSummaryOfNonHedgeInstrumentsDetails Derivatives - Summary of Non Hedge Instruments (Details) Details 132 false false R133.htm 996717 - Disclosure - Parent Company Only Financial Statements - Condensed Balance Sheets (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureParentCompanyOnlyFinancialStatementsCondensedBalanceSheetsDetails Parent Company Only Financial Statements - Condensed Balance Sheets (Details) Details 133 false false R134.htm 996727 - Disclosure - Parent Company Only Financial Statements - Condensed Statements of Income and Comprehensive Income (Loss) (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/DisclosureParentCompanyOnlyFinancialStatementsCondensedStatementsOfIncomeAndComprehensiveIncomeLossDetails Parent Company Only Financial Statements - Condensed Statements of Income and Comprehensive Income (Loss) (Details) Details 134 false false R135.htm 996737 - Disclosure - Parent Company Only Financial Statements - Condensed Statements of Cash Flows (Details) Sheet http://www.firstmid.com/20231231/taxonomy/role/Role_DisclosureParentCompanyOnlyFinancialStatementsCondensedStatementsOfCashFlowsDetails Parent Company Only Financial Statements - Condensed Statements of Cash Flows (Details) Details 135 false false All Reports Book All Reports fmbh-20231231.htm fmbh-20231231.xsd http://fasb.org/srt/2023 http://fasb.org/us-gaap/2023 http://xbrl.sec.gov/dei/2023 http://xbrl.sec.gov/ecd/2023 false false