3.20.2 html 649 461 1 false 106 0 false 10 false false R1.htm 0001001 - Document - Cover Sheet http://www.firstib.com/role/Cover Cover Cover 1 false false R2.htm 0103105 - Document - Premises and Equipment Sheet http://www.firstib.com/role/PremisesandEquipment Premises and Equipment Notes 2 false false R3.htm 0104107 - Document - Goodwill Sheet http://www.firstib.com/role/Goodwill Goodwill Uncategorized 3 false false R4.htm 0105109 - Document - Subordinated Debt Sheet http://www.firstib.com/role/SubordinatedDebt Subordinated Debt Cover 4 false false R5.htm 0106110 - Document - Benefit Plans Sheet http://www.firstib.com/role/BenefitPlans Benefit Plans Notes 5 false false R6.htm 0107114 - Document - Derivative Financial Instruments Sheet http://www.firstib.com/role/DerivativeFinancialInstruments Derivative Financial Instruments Uncategorized 6 false false R7.htm 1001002 - Statement - Condensed Consolidated Balance Sheets Sheet http://www.firstib.com/role/CondensedConsolidatedBalanceSheets Condensed Consolidated Balance Sheets Statements 7 false false R8.htm 1002003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) Sheet http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical Condensed Consolidated Balance Sheets (Parenthetical) Statements 8 false false R9.htm 1003004 - Statement - Condensed Consolidated Statements of Income (Unaudited) Sheet http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited Condensed Consolidated Statements of Income (Unaudited) Statements 9 false false R10.htm 1004005 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited) Sheet http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited Condensed Consolidated Statements of Comprehensive Income (Unaudited) Statements 10 false false R11.htm 1005006 - Statement - Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) Sheet http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) Statements 11 false false R12.htm 1006007 - Statement - Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical) Sheet http://www.firstib.com/role/ConsolidatedStatementsofShareholdersEquityUnauditedParenthetical Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical) Statements 12 false false R13.htm 1007008 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) Sheet http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited Condensed Consolidated Statements of Cash Flows (Unaudited) Statements 13 false false R14.htm 2101101 - Disclosure - Basis of Presentation Sheet http://www.firstib.com/role/BasisofPresentation Basis of Presentation Notes 14 false false R15.htm 2104102 - Disclosure - Earnings Per Share Sheet http://www.firstib.com/role/EarningsPerShare Earnings Per Share Notes 15 false false R16.htm 2107103 - Disclosure - Securities Sheet http://www.firstib.com/role/Securities Securities Notes 16 false false R17.htm 2114104 - Disclosure - Loans Sheet http://www.firstib.com/role/Loans Loans Notes 17 false false R18.htm 2126106 - Disclosure - Leases Sheet http://www.firstib.com/role/Leases Leases Notes 18 false false R19.htm 2132108 - Disclosure - Servicing Asset Sheet http://www.firstib.com/role/ServicingAsset Servicing Asset Notes 19 false false R20.htm 2144111 - Disclosure - Commitments and Credit Risk Sheet http://www.firstib.com/role/CommitmentsandCreditRisk Commitments and Credit Risk Notes 20 false false R21.htm 2146112 - Disclosure - Fair Value of Financial Instruments Sheet http://www.firstib.com/role/FairValueofFinancialInstruments Fair Value of Financial Instruments Notes 21 false false R22.htm 2152113 - Disclosure - Mortgage Banking Activities Sheet http://www.firstib.com/role/MortgageBankingActivities Mortgage Banking Activities Notes 22 false false R23.htm 2161115 - Disclosure - Accumulated Other Comprehensive Loss Sheet http://www.firstib.com/role/AccumulatedOtherComprehensiveLoss Accumulated Other Comprehensive Loss Notes 23 false false R24.htm 2164116 - Disclosure - Recent Accounting Pronouncements Sheet http://www.firstib.com/role/RecentAccountingPronouncements Recent Accounting Pronouncements Notes 24 false false R25.htm 2202201 - Disclosure - Basis of Presentation (Policies) Sheet http://www.firstib.com/role/BasisofPresentationPolicies Basis of Presentation (Policies) Policies http://www.firstib.com/role/RecentAccountingPronouncements 25 false false R26.htm 2305301 - Disclosure - Earnings Per Share (Tables) Sheet http://www.firstib.com/role/EarningsPerShareTables Earnings Per Share (Tables) Tables http://www.firstib.com/role/EarningsPerShare 26 false false R27.htm 2308302 - Disclosure - Securities (Tables) Sheet http://www.firstib.com/role/SecuritiesTables Securities (Tables) Tables http://www.firstib.com/role/Securities 27 false false R28.htm 2315303 - Disclosure - Loans (Tables) Sheet http://www.firstib.com/role/LoansTables Loans (Tables) Tables http://www.firstib.com/role/Loans 28 false false R29.htm 2323304 - Disclosure - Premises and Equipment (Tables) Sheet http://www.firstib.com/role/PremisesandEquipmentTables Premises and Equipment (Tables) Tables http://www.firstib.com/role/PremisesandEquipment 29 false false R30.htm 2327305 - Disclosure - Leases (Tables) Sheet http://www.firstib.com/role/LeasesTables Leases (Tables) Tables http://www.firstib.com/role/Leases 30 false false R31.htm 2333306 - Disclosure - Servicing Asset (Tables) Sheet http://www.firstib.com/role/ServicingAssetTables Servicing Asset (Tables) Tables http://www.firstib.com/role/ServicingAsset 31 false false R32.htm 2337307 - Disclosure - Subordinated Debt (Tables) Sheet http://www.firstib.com/role/SubordinatedDebtTables Subordinated Debt (Tables) Tables 32 false false R33.htm 2340308 - Disclosure - Benefit Plans (Tables) Sheet http://www.firstib.com/role/BenefitPlansTables Benefit Plans (Tables) Tables http://www.firstib.com/role/BenefitPlans 33 false false R34.htm 2347309 - Disclosure - Fair Value of Financial Instruments (Tables) Sheet http://www.firstib.com/role/FairValueofFinancialInstrumentsTables Fair Value of Financial Instruments (Tables) Tables http://www.firstib.com/role/FairValueofFinancialInstruments 34 false false R35.htm 2353310 - Disclosure - Mortgage Banking Activities (Tables) Sheet http://www.firstib.com/role/MortgageBankingActivitiesTables Mortgage Banking Activities (Tables) Tables http://www.firstib.com/role/MortgageBankingActivities 35 false false R36.htm 2355311 - Disclosure - Derivative Financial Instruments (Tables) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsTables Derivative Financial Instruments (Tables) Tables 36 false false R37.htm 2362312 - Disclosure - Accumulated Other Comprehensive Loss (Tables) Sheet http://www.firstib.com/role/AccumulatedOtherComprehensiveLossTables Accumulated Other Comprehensive Loss (Tables) Tables http://www.firstib.com/role/AccumulatedOtherComprehensiveLoss 37 false false R38.htm 2403401 - Disclosure - Basis of Presentation (Details) Sheet http://www.firstib.com/role/BasisofPresentationDetails Basis of Presentation (Details) Details http://www.firstib.com/role/BasisofPresentationPolicies 38 false false R39.htm 2406402 - Disclosure - Earnings Per Share (Details) Sheet http://www.firstib.com/role/EarningsPerShareDetails Earnings Per Share (Details) Details http://www.firstib.com/role/EarningsPerShareTables 39 false false R40.htm 2409403 - Disclosure - Securities (Details) Sheet http://www.firstib.com/role/SecuritiesDetails Securities (Details) Details http://www.firstib.com/role/SecuritiesTables 40 false false R41.htm 2410404 - Disclosure - Securities (Details Textual) Sheet http://www.firstib.com/role/SecuritiesDetailsTextual Securities (Details Textual) Details http://www.firstib.com/role/SecuritiesTables 41 false false R42.htm 2411405 - Disclosure - Securities - Carrying Value (Details) Sheet http://www.firstib.com/role/SecuritiesCarryingValueDetails Securities - Carrying Value (Details) Details 42 false false R43.htm 2412406 - Disclosure - Securities - Gross Unrealized Losses and Fair Value (Details) Sheet http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails Securities - Gross Unrealized Losses and Fair Value (Details) Details 43 false false R44.htm 2413407 - Disclosure - Securities Securities - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) Sheet http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails Securities Securities - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) Details 44 false false R45.htm 2416408 - Disclosure - Loans - Categories (Details) Sheet http://www.firstib.com/role/LoansCategoriesDetails Loans - Categories (Details) Details 45 false false R46.htm 2417409 - Disclosure - Loans - Change in the Balances of the ALLL (Details) Sheet http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails Loans - Change in the Balances of the ALLL (Details) Details 46 false false R47.htm 2418410 - Disclosure - Loans - Recorded Investments in Loans (Details) Sheet http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails Loans - Recorded Investments in Loans (Details) Details 47 false false R48.htm 2419411 - Disclosure - Loans - Nonaccrual Loans (Details) Sheet http://www.firstib.com/role/LoansNonaccrualLoansDetails Loans - Nonaccrual Loans (Details) Details 48 false false R49.htm 2420412 - Disclosure - Loans Loans - Internal Credit Assessment (Details) Sheet http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails Loans Loans - Internal Credit Assessment (Details) Details 49 false false R50.htm 2421413 - Disclosure - Loans - Loan Portfolio Aging (Details) Sheet http://www.firstib.com/role/LoansLoanPortfolioAgingDetails Loans - Loan Portfolio Aging (Details) Details 50 false false R51.htm 2422414 - Disclosure - Loans - Impaired Loans (Details) Sheet http://www.firstib.com/role/LoansImpairedLoansDetails Loans - Impaired Loans (Details) Details 51 false false R52.htm 2424415 - Disclosure - - Summary (Details) Sheet http://www.firstib.com/role/SummaryDetails - Summary (Details) Details 52 false false R53.htm 2425416 - Disclosure - Premises and Equipment - Narrative (Details) Sheet http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails Premises and Equipment - Narrative (Details) Details 53 false false R54.htm 2428417 - Disclosure - Leases (Details) Sheet http://www.firstib.com/role/LeasesDetails Leases (Details) Details http://www.firstib.com/role/LeasesTables 54 false false R55.htm 2429418 - Disclosure - Leases - Balance Sheet Amounts (Details) Sheet http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails Leases - Balance Sheet Amounts (Details) Details 55 false false R56.htm 2430419 - Disclosure - Leases - Maturity (Details) Sheet http://www.firstib.com/role/LeasesMaturityDetails Leases - Maturity (Details) Details 56 false false R57.htm 2431420 - Disclosure - Goodwill (Details) Sheet http://www.firstib.com/role/GoodwillDetails Goodwill (Details) Details 57 false false R58.htm 2434421 - Disclosure - Servicing Asset (Details) Sheet http://www.firstib.com/role/ServicingAssetDetails Servicing Asset (Details) Details http://www.firstib.com/role/ServicingAssetTables 58 false false R59.htm 2435422 - Disclosure - Servicing Asset - Unpaid principal balance (Details) Sheet http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails Servicing Asset - Unpaid principal balance (Details) Details 59 false false R60.htm 2436423 - Disclosure - Servicing Asset - Narrative (Details) Sheet http://www.firstib.com/role/ServicingAssetNarrativeDetails Servicing Asset - Narrative (Details) Details 60 false false R61.htm 2438424 - Disclosure - Subordinated Debt (Details Textual) Sheet http://www.firstib.com/role/SubordinatedDebtDetailsTextual Subordinated Debt (Details Textual) Details http://www.firstib.com/role/SubordinatedDebtTables 61 false false R62.htm 2439425 - Disclosure - Subordinated Debt - Schedule of Subordinated Debt (Details) Sheet http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails Subordinated Debt - Schedule of Subordinated Debt (Details) Details 62 false false R63.htm 2441426 - Disclosure - Benefit Plans - Activity (Details) Sheet http://www.firstib.com/role/BenefitPlansActivityDetails Benefit Plans - Activity (Details) Details 63 false false R64.htm 2442427 - Disclosure - Benefit Plans - Deferred Stock Rights (Details) Sheet http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails Benefit Plans - Deferred Stock Rights (Details) Details 64 false false R65.htm 2443428 - Disclosure - Benefit Plans (Details Textual) Sheet http://www.firstib.com/role/BenefitPlansDetailsTextual Benefit Plans (Details Textual) Details http://www.firstib.com/role/BenefitPlansTables 65 false false R66.htm 2445429 - Disclosure - Commitments and Credit Risk (Details) Sheet http://www.firstib.com/role/CommitmentsandCreditRiskDetails Commitments and Credit Risk (Details) Details http://www.firstib.com/role/CommitmentsandCreditRisk 66 false false R67.htm 2448430 - Disclosure - Fair Value of Financial Instruments - Fair Value Hierarchy (Details) Sheet http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails Fair Value of Financial Instruments - Fair Value Hierarchy (Details) Details 67 false false R68.htm 2449431 - Disclosure - Fair Value of Financial Instruments - Fair Value Roll Forward (Details) Sheet http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails Fair Value of Financial Instruments - Fair Value Roll Forward (Details) Details 68 false false R69.htm 2450432 - Disclosure - Fair Value of Financial Instruments - Quantative Information About Unobservable Inputs (Details) Sheet http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails Fair Value of Financial Instruments - Quantative Information About Unobservable Inputs (Details) Details 69 false false R70.htm 2451433 - Disclosure - Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value (Details) Sheet http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value (Details) Details 70 false false R71.htm 2454434 - Disclosure - Mortgage Banking Activities (Details) Sheet http://www.firstib.com/role/MortgageBankingActivitiesDetails Mortgage Banking Activities (Details) Details http://www.firstib.com/role/MortgageBankingActivitiesTables 71 false false R72.htm 2456435 - Disclosure - Derivative Financial Instruments - Carrying Amount and Adjustment (Details) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails Derivative Financial Instruments - Carrying Amount and Adjustment (Details) Details 72 false false R73.htm 2457436 - Disclosure - Derivative Financial Instruments - Interest Swap Derivatives (Details) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails Derivative Financial Instruments - Interest Swap Derivatives (Details) Details 73 false false R74.htm 2458437 - Disclosure - Derivative Financial Instruments - Notional Amounts and Fair Value (Details) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails Derivative Financial Instruments - Notional Amounts and Fair Value (Details) Details 74 false false R75.htm 2459438 - Disclosure - Derivative Financial Instruments - Gain (Loss) Recognized (Details) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails Derivative Financial Instruments - Gain (Loss) Recognized (Details) Details http://www.firstib.com/role/DerivativeFinancialInstrumentsTables 75 false false R76.htm 2460439 - Disclosure - Derivative Financial Instruments - Effect Of Derivatives on Income (Details) Sheet http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails Derivative Financial Instruments - Effect Of Derivatives on Income (Details) Details 76 false false R77.htm 2463440 - Disclosure - Accumulated Other Comprehensive Loss (Details) Sheet http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails Accumulated Other Comprehensive Loss (Details) Details http://www.firstib.com/role/AccumulatedOtherComprehensiveLossTables 77 false false All Reports Book All Reports inbk-20200630.htm ex311-2020q2.htm ex312-2020q2.htm ex321-2020q2.htm inbk-20200630.xsd inbk-20200630_cal.xml inbk-20200630_def.xml inbk-20200630_lab.xml inbk-20200630_pre.xml http://fasb.org/us-gaap/2020-01-31 http://xbrl.sec.gov/dei/2019-01-31 http://fasb.org/srt/2020-01-31 true true