Investments, Debt and Equity Securities [Abstract] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. government corporations and agencies US Government Corporations and Agencies Securities [Member] Mortgage and asset-backed securities Collateralized Mortgage Backed Securities [Member] Obligations of states and political subdivisions US States and Political Subdivisions Debt Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 12 months or longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Total Debt Securities, Available-for-sale, Unrealized Loss Position Less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 12 months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 months or longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Loans and Leases Receivable Disclosure [Abstract] Allowance for Loan Losses Allowance for Credit Losses [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative [Table] Derivative [Table] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Fair Value Hedging Fair Value Hedging [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Derivative [Line Items] Derivative [Line Items] Cash pledged as collateral Collateral Already Posted, Aggregate Fair Value Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other liabilities Other Liabilities [Member] Embedded Conversion Option Embedded Conversion Option [Member] Embedded Conversion Option [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other noninterest income Other Nonoperating Income (Expense) [Member] Derivative, notional amount Derivative, Notional Amount Number of shares to be issued upon conversion (in shares) Debt Instrument, Convertible, Number of Equity Instruments Number of shares issued upon conversion (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Noninterest income recorded for embedded conversion option Embedded Derivative, Gain (Loss) on Embedded Derivative, Net Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] First Bank Lubbock Bancshares, Inc. First Bank Lubbock Bancshares, Inc. [Member] First Bank Lubbock Bancshares, Inc. [Member] Signature Bancshares, Inc. Signature Bancshares, Inc. [Member] Signature Bancshares, Inc. [Member] Citywide Banks Citywide Banks of Colorado, Inc. [Member] Citywide Banks of Colorado, Inc. [Member] Founders Bancorp Founders Bancorp [Member] Founders Bancorp [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Core Deposits Core Deposits [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill Goodwill Goodwill impairment Goodwill, Impairment Loss Intangibles recognized Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Intangibles, amortization period Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Embedded derivatives Embedded Derivative Financial Instruments [Member] Other assets Other Assets [Member] Notional Amount Fair Value Embedded Derivative, Fair Value of Embedded Derivative Asset Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Nonrecurring Basis Fair Value, Measurements, Nonrecurring [Member] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Commercial Commercial Portfolio Segment [Member] Agricultural and agricultural real estate Agricultural Portfolio Segment [Member] Agricultural Portfolio Segment Residential real estate Residential Portfolio Segment [Member] Consumer Consumer Portfolio Segment [Member] Class of Financing Receivable [Axis] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Domain] Class of Financing Receivable, Type [Domain] Commercial Commercial Loan [Member] Commercial real estate Real Estate Loan [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Premises, furniture and equipment held for sale Property, Plant and Equipment [Member] Commercial servicing rights Commercial Servicing Rights [Member] Commercial Servicing Rights [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Year-to- Date (Gains) Losses Changes Measurement [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Collateral dependent impaired loans Collateral Dependent Impaired Loans Collateral Dependent Impaired Loans Loans held for sale Loans Held-for-sale, Fair Value Disclosure Other real estate owned Real Estate Acquired Through Foreclosure Premises, furniture and equipment held for sale Assets Held-for-sale, Not Part of Disposal Group Servicing rights Servicing Asset at Fair Value, Amount Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Total debt securities Debt Securities [Member] Equity securities with a readily determinable fair value Equity Securities [Member] Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Equity securities with a readily determinable fair value Equity Securities, FV-NI Total Marketable Securities, Amortized Cost Basis Marketable Securities, Amortized Cost Basis Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Estimated Fair Value Debt Securities, Available-for-sale Estimated Fair Value Marketable Securities Amortized Cost Available-for-sale Securities, Amortized Cost Basis Gross Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Securities available for sale Available-for-sale Securities Derivative, by Nature [Axis] Derivative, Name [Domain] Cash Flow Hedges Cash Flow Hedging [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Heartland Financial Statutory Trust IV, V and VII Heartland Financial Statutory Trust IV, V and VII [Member] Heartland Financial Statutory Trust IV, V and VII [Member] Morrill Statutory Trust I and II Morrill Statutory Trust I and II [Member] Morrill Statutory Trust I and II [Member] OCGI Statutory Trust III OCGI Statutory Trust III [Member] OCGI Statutory Trust III [Member] OCGI Capital Trust IV OCGI Capital Trust IV [Member] OCGI Capital Trust IV [Member] Change in net unrealized losses on cash flow hedges Unrealized Gain (Loss) on Cash Flow Hedging Instruments Estimated amount to be reclassified from accumulated other comprehensive income to interest expense within the next twelve months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Number of swap transactions Number of Interest Rate Derivatives Held Derivative, notional amount Derivative, Amount of Hedged Item Organization, Consolidation and Presentation of Financial Statements [Abstract] Earnings Per Share Earnings Per Share [Abstract] Net income Net Income (Loss) Attributable to Parent Preferred dividends Preferred Stock Dividends, Income Statement Impact Interest expense on convertible preferred debt Tax Expense (Benefit) on Interest on Convertible Debt Tax Expense (Benefit) on Interest on Convertible Debt NET INCOME AVAILABLE TO COMMON STOCKHOLDERS Net Income (Loss) Available to Common Stockholders, Basic Weighted average common shares outstanding for basic earnings per share (in shares) Weighted Average Number of Shares Outstanding, Basic Assumed incremental common shares issued upon non-vested restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted average common shares for diluted earnings per share (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per common share — basic (in dollars per share) Earnings Per Share, Basic Earnings per common share — diluted (in dollars per share) Earnings Per Share, Diluted Number of antidilutive common stock equivalents excluded from diluted earnings per share computation (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Time deposits in other financial institutions Certificates of Deposit [Member] Demand deposits Demand Deposits [Member] Savings deposits Interest-bearing Deposits [Member] Time deposits Bank Time Deposits [Member] Interest rate lock commitments Interest Rate Lock Commitments [Member] Forward commitments Forward Contracts [Member] Carrying Amount Reported Value Measurement [Member] Estimated Fair Value Estimate of Fair Value Measurement [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Financial assets: Assets, Fair Value Disclosure [Abstract] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Time deposits in other financial institutions Time Deposits, Fair Value Disclosure Time Deposits, Fair Value Disclosure Securities: Investments [Abstract] Securities available for sale Held to maturity Debt Securities, Held-to-maturity, Fair Value Other investments Other Investments Loans, net Loans Receivable, Fair Value Disclosure Cash surrender value on life insurance Cash Surrender Value, Fair Value Disclosure Derivative assets Derivative Asset Financial liabilities: Financial Liabilities Fair Value Disclosure [Abstract] Deposits Deposits, Fair Value Disclosure Short term borrowings Short-term Debt, Fair Value Other borrowings Long-term Debt, Fair Value Derivative liabilities Derivative Liability Back-to-Back Loan Swaps Back-to-back Loan Swaps [Member] Back-to-back Loan Swaps [Member] Counterparties Counterparties [Member] Counterparties [Member] Interest income Interest Income [Member] Gain (loss) recognized Gain (Loss) on Derivative Instruments, Net, Pretax Trading Activities, Gain and Losses, by Type, by Income Statement Location [Table] Trading Activities, Gain and Losses, by Type, by Income Statement Location [Table] Net gains on sale of loans held for sale Gain on Sale Of Loans Held For Sale [Member] Gain on Sale Of Loans Held For Sale [Member] Interest rate lock commitments (mortgage) Undesignated interest rate swaps Interest Rate Contract [Member] Trading Activity, Gains and Losses, Net [Line Items] Trading Activity, Gains and Losses, Net [Line Items] Gain (Loss) Recognized Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Revenue from Contract with Customer [Abstract] Schedule of noninterest income in-scope and out-of-scope of Topic 606 Disaggregation of Revenue [Table Text Block] Receivables [Abstract] Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] Residential real estate Consumer Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Domain] Financing Receivables, Period Past Due [Domain] 30-59 Days Past Due Financing Receivables, 30 to 59 Days Past Due [Member] 60-89 Days Past Due Financing Receivables, 60 to 89 Days Past Due [Member] 90 Days or More Past Due Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Accruing Loans and Leases, Past Due Financing Receivable, Recorded Investment, Past Due Accruing Loans and Leases, Current Financing Receivable, Recorded Investment, Current Nonaccrual Financing Receivable, Recorded Investment, Nonaccrual Status Total Financing Receivable, Gross Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Measurements, Nonrecurring Fair Value Measurements, Nonrecurring [Table Text Block] Fair Value Inputs, Assets, Quantitative Information Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of Loans Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Allowance for Loan and Lease Losses, Based on Impairment Methodology Allowance For Loan And Lease Losses, Based On Impairment Methodology [Table Text Block] Allowance For Loan And Lease Losses, Based On Impairment Methodology [Table Text Block] Schedule of Financing Receivables, Non Accrual Status Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Troubled Debt Restructuring on Loans Modified Troubled Debt Restructurings on Financing Receivables [Table Text Block] Financing Receivable Credit Quality Indicators Financing Receivable Credit Quality Indicators [Table Text Block] Past Due Financing Receivables Past Due Financing Receivables [Table Text Block] Summary of Impaired Loans Impaired Financing Receivables [Table Text Block] Changes in Accretable Yield on Acquired Loans Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table Text Block] Loans Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Position [Axis] Position [Axis] Position [Domain] Position [Domain] Receive Rate Long [Member] Pay Rate Short [Member] Fair Value, Other Assets Interest Rate Derivative Assets, at Fair Value Fair Value, Other Liabilities Interest Rate Derivative Liabilities, at Fair Value Weighted Average Interest Rate (in percent) Derivative, Average Variable Interest Rate Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Dubuque Bank and Trust Company Dubuque Bank and Trust Company [Member] Dubuque Bank and Trust Company [Member] First Bank & Trust First Bank & Trust [Member] First Bank & Trust [Member] Premier Valley Bank Premier Valley Bank [Member] Premier Valley Bank [Member] Wisconsin Bank & Trust Wisconsin Bank & Trust [Member] Wisconsin Bank & Trust [Member] 15 Years Mortgage Servicing Rights 15 Year [Member] Mortgage Servicing Rights 15 Year [Member] 30 Years Mortgage Servicing Rights 30 Year [Member] Mortgage Servicing Rights 30 Year [Member] Less Than 20 Years Commercial Servicing Rights less than 20 Years [Member] Commercial Servicing Rights less than 20 Years [Member] More Than 20 Years Commercial Servicing Rights more than 20 Years [Member] Commercial Servicing Rights more than 20 Years [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Book Value Servicing Asset at Amortized Cost Fair Value Servicing Asset at Amortized Cost, Fair Value Impairment Servicing Asset at Amortized Cost, Increase (Decrease) for Valuation Allowance Adjustment New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] AOCI Attributable to Parent AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2016-01 Accounting Standards Update 2016-01 [Member] ASU 2018-02 Accounting Standards Update 2018-02 [Member] Accounting Standards Update 2018-02 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Reclassification of unrealized net gain on equity securities Cumulative Effect of New Accounting Principle in Period of Adoption Cumulative-effect adjustment Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Class of Financing Receivable, Type [Axis] Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Line Items] Ending Balance Under ASC 310-10-35 Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Ending Balance Under ASC 450-20 Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Total Financing Receivable, Allowance for Credit Losses Ending Balance Evaluated for Impairment Under ASC 310-10-35 Financing Receivable, Individually Evaluated for Impairment Ending Balance Evaluated for Impairment Under ASC 450-20 Financing Receivable, Collectively Evaluated for Impairment Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Stock-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Subsequent Events Subsequent Events, Policy [Policy Text Block] Effect of New Financial Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Fair Value Hierarchy Fair Value of Financial Instruments, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Nonaccrual loans Nonaccrual Loans Nonaccrual Loans Nonaccrual troubled debt restructured loans Financing Receivable, Modifications, Recorded Investment, Nonaccrual Status Financing Receivable, Modifications, Recorded Investment, Nonaccrual Status Total nonaccrual loans Accruing loans past due 90 days or more Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Performing troubled debt restructured loans Financing Receivable, Modifications, Recorded Investment, Performing Financing Receivable, Modifications, Recorded Investment, Performing Statement of Comprehensive Income [Abstract] OTHER COMPREHENSIVE INCOME (LOSS) Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Securities: Securities [Abstract] Note 3: Securities [Abstract] Net change in unrealized gain (loss) on securities Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Reclassification adjustment for net (gains)/losses realized in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Income taxes Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax Other comprehensive income (loss) on securities Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Derivatives used in cash flow hedging relationships: Net change in unrealized gain (loss) on derivatives Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Reclassification adjustment for net losses on derivatives realized in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Income taxes Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Other comprehensive income on cash flow hedges Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax TOTAL COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] RSUs Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Shares Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Outstanding at beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures Outstanding at end of period (in shares) Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Outstanding at beginning of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Exercises in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Exercises in Period, Weighted Average Grant Date Fair Value Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Outstanding at end of period (in dollars per share) Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Closing Ratio Closing Ratio [Member] Closing Ratio [Member] Appraisal discount Measurement Input, Appraised Value [Member] Valuation discount Measurement Input, Discount Rate [Member] Heartland Legacy Mortgage Operations Heartland Legacy Mortgage Operations [Member] Heartland Legacy Mortgage Operations [Member] PrimeWest Mortgage Corporation PrimeWest Mortgage Corporation [Member] PrimeWest Mortgage Corporation [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Weighted Average Weighted Average [Member] Minimum Minimum [Member] Maximum Maximum [Member] Level 3 Collateralized Debt Obligations [Member] Collateralized Debt Obligations [Member] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Commercial servicing rights Closing ratio Derivative Asset, Measurement Input Pretax discount rate (percent) Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate Business Combinations [Abstract] Acquisitions Business Combination Disclosure [Text Block] Schedule of Recognized Identified Assets Acquired and Liabilities Assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Summary of Pro Forma Information Business Acquisition, Pro Forma Information [Table Text Block] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Fair value hedges Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Amount of Gain (Loss) Gain (Loss) on Fair Value Hedges Recognized in Earnings Fair Value Fair Value Hedge Assets Fair Value Fair Value Hedge Liabilities Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Investment [Table] Investment [Table] Mortgage-backed Securities, Issued by US Government Sponsored Enterprises Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Investment [Line Items] Investment [Line Items] Reclassification of unrealized gain in fair value on equity securities Equity securities with a readily determinable fair value Equity Securities, FV-NI, Cost Equity securities, at fair value Unrealized net gains on equity securities recognized in current earnings Equity Securities, FV-NI, Unrealized Gain (Loss) Percentage of mortgage and asset-backed securities issued by government-sponsored enterprises Percentage of Heartland's Mortgage-backed Securities, Issued by US Government Sponsored Enterprises Percentage of Heartland's Mortgage-backed Securities, Issued by US Government Sponsored Enterprises Fair value of securities pledged Pledged Assets Separately Reported, Securities Pledged as Collateral, at Fair Value Gross realized gains on available-for-sale securities Debt Securities, Available-for-sale, Realized Gain (Loss) Equity securities without readily determinable fair value Equity Securities without Readily Determinable Fair Value, Amount Shares of stock in FHLB Federal Home Loan Bank Stock Income Statement [Abstract] Statement [Table] Statement [Table] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Accumulated Net Gain (Loss) from Derivatives Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Accumulated Net Unrealized Investment Gain (Loss) Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) Statement [Line Items] Statement [Line Items] Interest expense related to derivatives reclassified from accumulated other comprehensive income Interest Expense, Other Long-term Debt Net security gains reclassified from accumulated other comprehensive income Debt and Equity Securities, Gain (Loss) Income tax expense (benefit) reclassified from accumulated other comprehensive income Income Tax Expense (Benefit) Future amortization expense for amortizable intangible assets [Table] Future amortization expense for amortizable intangible assets [Table] Future amortization expense for amortizable intangible assets [Table] Core deposit intangibles Customer relationship intangibles Customer Relationships [Member] Mortgage servicing rights Mortgage Servicing Rights [Member] Mortgage Servicing Rights [Member] Future amortization expense for amortizable intangible assets [Line Items] Future amortization expense for amortizable intangible assets [Line Items] Future amortization expense for amortizable intangible assetse [Line Items] Three months ending December 31, 2018 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Year ending December 31, Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2019 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Total Finite-Lived Intangible Assets, Net Schedule of Servicing Assets at Fair Value [Table] Schedule of Servicing Assets at Fair Value [Table] Mortgage Servicing Rights Servicing Assets at Fair Value [Line Items] Servicing Assets at Fair Value [Line Items] Servicing Asset at Fair Value, Amount [Roll Forward] Servicing Asset at Fair Value, Amount [Roll Forward] Balance at beginning of period Originations Servicing Asset at Fair Value, Other Changes in Fair Value Amortization Servicing Asset at Amortized Cost, Amortization Valuation allowance on commercial servicing rights Commercial Servicing Rights (CSR) Impairment (Recovery) Commercial Servicing Rights (CSR) Impairment (Recovery) Sale of mortgage servicing rights Servicing Asset at Fair Value, Disposals Acquired mortgage servicing rights Servicing Asset at Fair Value, Additions Balance at end of period Fair value of commercial servicing rights Commercial servicing rights, net to servicing portfolio Servicing Asset, Net to Servicing Portfolio, Percentage Servicing Asset, Net to Servicing Portfolio, Percentage Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] 2015, 2016 and 2017 Acquisitions Two Thousand Fifteen, Two Thousand Sixteen, And Two Thousand Seventeen Acquisitions [Member] Two Thousand Fifteen, Two Thousand Sixteen, And Two Thousand Seventeen Acquisitions [Member] 2015 Acquisitions Two Thousand Fifteen Acquisitions [Member] Two Thousand Fifteen Acquisitions [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Non Impaired Purchased Loans Financing Receivables Excluding Acquired With Deteriorated Credit Quality [Member] Financing Receivables Excluding Acquired With Deteriorated Credit Quality [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Contractually required payments of loans acquired Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition Estimated fair value of loans acquired Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value Allowance for loan and lease losses Loans and Leases Receivable, Allowance Provision for loan losses Provision for Loan and Lease Losses Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Net amortization of premium on securities Accretion (Amortization) of Discounts and Premiums, Investments Securities gains, net Unrealized gain on equity securities, net Increase (Decrease) in Equity Securities, FV-NI Stock based compensation Share-based Compensation Loans originated for sale Payments for Origination and Purchases of Loans Held-for-sale Proceeds on sales of loans held for sale Proceeds from Sale of Loans Held-for-sale Net gains on sale of loans held for sale Gain (Loss) on Sales of Loans, Net Increase in accrued interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Decrease in prepaid expenses Increase (Decrease) in Prepaid Expense Decrease in accrued interest payable Increase (Decrease) in Interest Payable, Net Capitalization of servicing rights Payments to Acquire Mortgage Servicing Rights (MSR), Operating Activities Payments to Acquire Mortgage Servicing Rights (MSR), Operating Activities Valuation allowance on servicing rights Loss on sales/valuations of assets, net Gain (Loss) on Disposition of Assets Net excess tax benefit from stock based compensation Deferred Tax Expense from Stock Options Exercised Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net NET CASH PROVIDED BY OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchase of time deposits in other financial institutions Payments for Deposits with Other Institutions Proceeds from the sale of securities available for sale Proceeds from Sale of Debt Securities, Available-for-sale Proceeds from the redemption of time deposits in other financial institutions Proceeds from (Payments for) in Interest-bearing Deposits in Banks Proceeds from the maturity of and principal paydowns on securities available for sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Proceeds from the maturity of and principal paydowns on securities held to maturity Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Proceeds from the maturity of and principal paydowns on time deposits in other financial institutions Proceeds from Maturities, Prepayments and Calls of Other Securities Proceeds from Maturities, Prepayments and Calls of Other Securities Proceeds from the maturity of and principal paydowns on other investments Proceeds from Maturities, Prepayments and Calls of Other Investments Purchase of securities available for sale Payments to Acquire Debt Securities, Available-for-sale Purchase of other investments Payments to Acquire Other Investments Net (increase) decrease in loans Payments for (Proceeds from) Loans and Leases Purchase of bank owned life insurance policies Payment to Acquire Life Insurance Policy, Investing Activities Proceeds from sale of mortgage servicing rights Proceeds from Sale of Mortgage Servicing Rights (MSR) Capital expenditures Payments to Acquire Property, Plant, and Equipment Net cash and cash equivalents received in acquisitions Proceeds from Divestiture of Businesses, Net of Cash Divested Proceeds from the sale of equipment Proceeds from Sale of Property, Plant, and Equipment Proceeds on sale of OREO and other repossessed assets Proceeds from Sale of Foreclosed Assets NET CASH PROVIDED BY INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Net increase in demand deposits Increase (Decrease) in Demand Deposits Net increase (decrease) in savings deposits Increase (Decrease) in Savings Deposits Net decrease in time deposit accounts Increase (Decrease) in Time Deposits Proceeds on short-term revolving credit line Proceeds from Lines of Credit Repayments on short-term revolving credit line Repayments of Lines of Credit Net decrease in short-term borrowings Proceeds from (Repayments of) Short-term Debt Proceeds from short term FHLB advances Proceeds from FHLBank Borrowings, Financing Activities Repayments of short term FHLB advances Payments of FHLBank Borrowings, Financing Activities Proceeds from other borrowings Proceeds from Issuance of Long-term Debt Repayments of other borrowings Repayments of Long-term Debt Purchase of treasury stock Payments for Repurchase of Common Stock Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Dividends paid Payments of Dividends NET CASH USED BY FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities Net increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value CASH AND CASH EQUIVALENTS AT END OF PERIOD Supplemental disclosures: Supplemental Cash Flow Information [Abstract] Cash paid for income/franchise taxes Income Taxes Paid Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Loans transferred to OREO Real Estate Owned, Transfer to Real Estate Owned Transfer of premises from premises, furniture and equipment, net, to premises, furniture and equipment held for sale Transfer Of Property, Plant And Equipment, Net To Assets Held-For-Sale Transfer Of Property, Plant And Equipment, Net To Assets Held-For-Sale Deposits transferred to held for sale Transfer Of Deposits To Held-for-sale Transfer Of Deposits To Held-for-sale Loans transferred to held for sale Transfer of Portfolio Loans and Leases to Held-for-sale Purchases of securities available for sale, accrued, not settled Purchases of available for sale securities, accrued, not paid Purchases of available for sale securities, accrued, not paid Sales of securities available for sale, accrued, not settled Sale of Available-for-sale Securities, Noncash Sale of Available-for-sale Securities, Noncash Conversion of convertible debt to common stock Debt Conversion, Converted Instrument, Amount Conversion of Series D preferred stock to common stock Conversion of Stock, Amount Converted Stock consideration granted for acquisitions Stock Issued During Period, Value, Acquisitions Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Interest Rate Swap due March 17, 2021 Interest Rate Swap due March 17, 2021 [Member] Interest Rate Swap due March 17, 2021 [Member] Interest Rate Swap due January 7, 2020 Interest Rate Swap due January 7, 2020 [Member] Interest Rate Swap due January 7, 2020 [Member] Interest Rate Swap due March 26, 2019 Interest Rate Swap due March 26, 2019 [Member] Interest Rate Swap due March 26, 2019 [Member] Interest Rate Swap due March 18, 2019 Interest Rate Swap due March 18, 2019 [Member] Interest Rate Swap due March 18, 2019 [Member] Interest Rate Swap due May 10, 2021 Interest Rate Swap due May 10, 2021 [Member] Interest Rate Swap due May 10, 2021 [Member] Interest Rate Swap Due July 24, 2028 Interest Rate Swap Due July 24, 2028 [Member] Interest Rate Swap Due July 24, 2028 [Member] Interest Rate Swap due June 15, 2024 Interest Rate Swap due June 15, 2024 [Member] Interest Rate Swap due June 15, 2024 [Member] Interest Rate Swap due March 1, 2024 Interest Rate Swap due March 1, 2024 [Member] Interest Rate Swap due March 1, 2024 [Member] Interest Rate Swap Due June 15, 2021 Interest Rate Swap Due June 15, 2021 [Member] Interest Rate Swap Due June 15, 2021 [Member] Interest Rate Swap Due June 30, 2021 Interest Rate Swap Due June 30, 2021 [Member] Interest Rate Swap Due June 30, 2021 [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Notional Amount, Other Assets Derivative Asset, Notional Amount Notional Amount, Other Liabilities Derivative Liability, Notional Amount Receive Rate Interest Rate Cash Flow Hedge Derivative, Receive Rate, Percentage Interest Rate Cash Flow Hedge Derivative, Receive Rate, Percentage Weighted Average Pay Rate Interest Rate Cash Flow Hedge Derivative, Weighted Average Pay Rate, Percentage Interest Rate Cash Flow Hedge Derivative, Weighted Average Pay Rate, Percentage Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Preferred Stock Preferred Stock [Member] Common Stock Common Stock [Member] Capital Surplus Additional Paid-in Capital [Member] Treasury Stock Treasury Stock [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series D Preferred Stock Series D Preferred Stock [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance at beginning of period Stockholders' Equity Attributable to Parent Comprehensive income Cash dividends declared: Dividends [Abstract] Preferred Dividends, Preferred Stock Common Dividends, Common Stock Conversion of Series D preferred stock Stock Issued During Period, Value, Conversion of Convertible Securities Purchase of shares of common stock Treasury Stock, Value, Acquired, Cost Method Issuance of shares of common stock Stock Issued During Period, Value, Treasury Stock Reissued Stock based compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Balance at end of period Revenue Revenue from Contract with Customer [Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Trust Preferred Securities Subject to Mandatory Redemption Trust Preferred Securities Subject to Mandatory Redemption [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Total consideration transferred in acquisition Business Combination, Consideration Transferred Purchase price in cash Payments to Acquire Businesses, Gross Purchase price paid by delivery of shares of common stock (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Outstanding debt extinguished Extinguishment of Debt, Amount Trust preferred securities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Borrowings Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Borrowings Payment to holders of FBLB's stock appreciation rights Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards Total assets acquired Business Combination, Recognized Identifiable Assets Acquired And Goodwill Business Combination, Recognized Identifiable Assets Acquired And Goodwill Held to maturity Loans and Leases Receivable, Net of Deferred Income Deposits acquired Deposits Goodwill resulting from acquisition Transaction costs Business Acquisition, Transaction Costs Pre-tax merger related costs Business Combination, Acquisition Related Costs Balance of nonaccrual loans Assets acquired Assets Number of bank buildings sold (building) Business Combination, Number of Buildings Acquired Business Combination, Number of Buildings Acquired Fair value of buildings sold Fair Value, Sale of Buildings Fair Value, Sale of Buildings Loans acquired Loans and Leases Receivable, at Fair Value Loans and Leases Receivable, at Fair Value Statement of Financial Position [Abstract] Series A Junior Participating Preferred Stock Series A Preferred Stock [Member] Series C Senior Non-Cumulative Perpetual Preferred Stock Series C Preferred Stock [Member] Series D Senior Non-Cumulative Perpetual Preferred Stock ASSETS Assets [Abstract] Cash and due from banks Cash and Due from Banks Interest bearing deposits with the Federal Reserve Bank and other banks and other short-term investments Interest-bearing Deposits in Banks and Other Financial Institutions Cash and cash equivalents Time deposits in other financial institutions Time Deposits, at Carrying Value Securities: Marketable Securities [Abstract] Carried at fair value (cost of $2,342,977 at September 30, 2018, and $2,248,181 at December 31, 2017) Held to maturity, at cost (fair value of $247,394 at September 30, 2018, and $265,494 at December 31, 2017) Debt Securities, Held-to-maturity Other investments, at cost Other Investments and Securities, at Cost Loans held for sale Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Other Loans receivable: Loans and Leases Receivable, Net Amount [Abstract] Allowance for loan and lease losses Loans receivable, net Loans and Leases Receivable, Net Amount Premises, furniture and equipment, net Property, Plant and Equipment, Net Other real estate, net Core deposit intangibles and customer relationship intangibles, net Intangible Assets, Net, Excluding Goodwill And Servicing Rights Intangible Assets, Net, Excluding Goodwill And Servicing Rights Servicing rights, net Servicing Asset Cash surrender value on life insurance Bank Owned Life Insurance Other assets Other Assets TOTAL ASSETS LIABILITIES AND EQUITY Liabilities and Equity [Abstract] LIABILITIES: Liabilities [Abstract] Deposits: Deposits [Abstract] Demand Noninterest-bearing Deposit Liabilities, Domestic Savings Deposits, Savings Deposits Time Time Deposits Total deposits Deposits held for sale Deposits Held For Sale Deposits Held For Sale Short-term borrowings Short-term Debt Other borrowings Other Long-term Debt Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities TOTAL LIABILITIES Liabilities STOCKHOLDERS' EQUITY: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred stock Preferred Stock, Value, Issued Common stock (par value $1 per share; 40,000,000 shares authorized at both September 30, 2018, and December 31, 2017; issued 34,473,029 shares at September 30, 2018, and 29,953,356 shares at December 31, 2017) Common Stock, Value, Issued Capital surplus Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury stock at cost (0 shares at both September 30, 2018, and December 31, 2017) Treasury Stock, Value TOTAL STOCKHOLDERS' EQUITY TOTAL LIABILITIES AND EQUITY Liabilities and Equity Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of Loans Financing Receivable, Modifications, Number of Contracts Pre- Modification Recorded Investment Financing Receivable, Modifications, Pre-Modification Recorded Investment Post- Modification Recorded Investment Financing Receivable, Modifications, Post-Modification Recorded Investment With Payment Defaults During the Financing Receivable, Subsequent Default [Abstract] Financing Receivable, Subsequent Default [Abstract] Number of Loans Financing Receivable, Modifications, Subsequent Default, Number of Contracts Recorded Investment Financing Receivable, Modifications, Subsequent Default, Recorded Investment Debt Securities, Held-to-maturity [Table] Debt Securities, Held-to-maturity [Table] Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Amortized Cost Gross Unrealized Gains Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain Gross Unrealized Losses Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss Estimated Fair Value Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Long-Term Incentive Plan 2012 Long-Term Incentive Plan 2012 [Member] Long-Term Incentive Plan 2012 [Member] Time-based RSUs Time-based RSUs [Member] Time-based RSUs [Member] Performance-Based RSUs Performance-Based Restricted Stock Units [Member] Performance-Based Restricted Stock Units [Member] Stock Options Equity Option [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Period One Share-based Compensation Award, Tranche One [Member] Period Two Share-based Compensation Award, Tranche Two [Member] Period Three Share-based Compensation Award, Tranche Three [Member] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] 2017 and 2018 RSUs Restricted Stock Unit Grants In 2017 And 2018 [Member] Restricted Stock Unit Grants In 2017 And 2018 [Member] Prior to 2009 Prior to 2009 [Member] Prior to 2009 [Member] Number of shares for issuance under future awards (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Tax benefit from equity based awards Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount Equity instruments other than options, granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based compensation, award vesting periods Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-based compensation, vesting percentage after change in control Share-based Compensation Arrangement By Share-based Payment Award, Vesting Percentage After Change In Control Share-based Compensation Arrangement By Share-based Payment Award, Vesting Percentage After Change In Control Share-based compensation, period before change in control Share-based Compensation Arrangement by Share-based Payment Award, Period Before Change In Control Share-based Compensation Arrangement by Share-based Payment Award, Period Before Change In Control Share-based compensation, vesting period after change in control Share-based Compensation Arrangement by Share-based Payment Award, Vesting Period After Change In Control Share-based Compensation Arrangement by Share-based Payment Award, Vesting Period After Change In Control Share-based compensation costs Allocated Share-based Compensation Expense Share-based unrecognized compensation costs Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Typical options expiration period after date of grant Share-based Compensation Arrangement by Share-based Payment Award, Options Expiration Period After Date of Grant Share-based Compensation Arrangement by Share-based Payment Award, Options Expiration Period After Date of Grant Intrinsic value for the total of all options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Cash received from options exercised Proceeds from Stock Options Exercised Options vested during period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Service charges and fees Financial Service [Member] Trust fees Fiduciary and Trust [Member] Brokerage and insurance commissions Financial Service, Brokerage And Insurance Commissions [Member] Financial Service, Brokerage And Insurance Commissions [Member] INTEREST INCOME: Interest Income (Expense), Net [Abstract] Interest and fees on loans Interest and Fee Income, Loans and Leases Interest on securities: Interest and Dividend Income, Securities, by Taxable Status [Abstract] Taxable Interest Income, Securities, Operating, Taxable Nontaxable Interest Income, Securities, Operating, Tax Exempt Interest on federal funds sold Interest Income, Federal Funds Sold Interest on interest bearing deposits in other financial institutions Interest Income, Deposits with Financial Institutions TOTAL INTEREST INCOME Interest and Dividend Income, Operating INTEREST EXPENSE: Interest Expense [Abstract] Interest on deposits Interest Expense, Deposits Interest on short-term borrowings Interest Expense, Short-term Borrowings Interest on other borrowings (includes $242 and $308 of interest expense related to derivatives reclassified from accumulated other comprehensive income for the three months ended September 30, 2018 and 2017, respectively, and $469 and $1,005 of interest expense related to derivatives reclassified from accumulated other comprehensive income for the nine months ended September 30, 2018 and 2017, respectively) TOTAL INTEREST EXPENSE Interest Expense NET INTEREST INCOME Interest Income (Expense), Net NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES Interest Income (Expense), after Provision for Loan Loss NONINTEREST INCOME: Noninterest Income [Abstract] Revenue from contract with customers Revenue from Contract with Customer, Excluding Assessed Tax Loan servicing income Investment Banking, Advisory, Brokerage, and Underwriting Fees and Commissions Securities gains/(losses), net (includes $145 of net security losses and $1,679 of net security gains reclassified from accumulated other comprehensive income for the three months ended September 30, 2018 and 2017, respectively, and $1,037 and $5,553 of net security gains reclassified from accumulated other comprehensive income for the nine months ended September 30, 2018 and 2017, respectively) Unrealized gain on equity securities, net Net gains on sale of loans held for sale Gain (Loss) on Sale of Loans and Leases Income on bank owned life insurance Bank Owned Life Insurance Income Other noninterest income Noninterest Income, Other Operating Income TOTAL NONINTEREST INCOME Noninterest Income NONINTEREST EXPENSES: Noninterest Expense [Abstract] Salaries and employee benefits Labor and Related Expense Occupancy Occupancy, Net Furniture and equipment Equipment Expense Professional fees Professional Fees FDIC insurance assessments Federal Deposit Insurance Corporation Premium Expense Advertising Advertising Expense Core deposit intangibles and customer relationship intangibles amortization Amortization of Intangible Assets Other real estate and loan collection expenses Gains (Losses) on Sales of Other Real Estate Loss on sales/valuations of assets, net Gain (Loss) on Disposition of Assets for Financial Service Operations Restructuring expenses Restructuring Charges Other noninterest expenses Other Noninterest Expense TOTAL NONINTEREST EXPENSES Noninterest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income taxes (includes $(26) and $511 of income tax expense/(benefit) reclassified from accumulated other comprehensive income for the three months ended September 30, 2018 and 2017, respectively, and $174 and $1,696 of income tax expense/(benefit) reclassified from accumulated other comprehensive income for the nine months ended September 30, 2018 and 2017, respectively) NET INCOME EARNINGS PER COMMON SHARE - BASIC (in dollars per share) EARNINGS PER COMMON SHARE - DILUTED (in dollars per share) CASH DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share) Common Stock, Dividends, Per Share, Declared Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Doubtful Doubtful [Member] Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment [Line Items] Principal deferment collected from government guarantees Financing Receivable, Modifications, Increase (Decrease) In Recorded Investment, Collection of Guarantees Financing Receivable, Modifications, Increase (Decrease) In Recorded Investment, Collection of Guarantees Capitalized interest and escrow Financing Receivable, Modifications, Increase (Decrease) In Recorded Investment, Capitalized Interest And Escrow Financing Receivable, Modifications, Increase (Decrease) In Recorded Investment, Capitalized Interest And Escrow Number of loan relationships Financing Receivable, Number of Loans Financing Receivable, Number of Loans Valuation servicing rights in tranches [Table] Valuation servicing rights in tranches [Table] Valuation servicing rights in tranches [Table] Measurement Input, Cap Rate Measurement Input, Cap Rate [Member] Mortgage Servicing Rights 15-year Tranche Mortgage Servicing Rights 15-year Tranche [Member] Mortgage Servicing Rights 15-year Tranche [Member] Mortgage Servicing Rights 30-year Tranche Mortgage Servicing Rights 30-year Tranche [Member] Mortgage Servicing Rights 30-year Tranche [Member] Commercial Servicing Rights Valuation servicing rights in tranches [Line Items] Valuation servicing rights in tranches [Line Items] Valuation servicing rights in tranches [Line Items] Mortgage loans serviced for others Mortgage Loans Serviced for Others, Amount Mortgage Loans Serviced for Others, Amount Custodial escrow balances maintained Escrow Deposit Servicing asset at amortized value Book value of loans Servicing asset, agreement term Servicing Asset, Agreement Term Servicing Asset, Agreement Term Number of subsidiaries Number Of Subsidiaries Number Of Subsidiaries Total net loans receivable held to maturity Servicing Asset At Fair Value, Disposals, Unpaid Principal Balance Servicing Asset At Fair Value, Disposals, Unpaid Principal Balance Amount derecognized Prepayment rate Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed Discount rate Average capitalization rate (percent) Servicing Asset, Measurement Input Fees collected for servicing of mortgage loans Fees and Commissions, Mortgage Banking and Servicing Loans serviced Valuation allowance Amortization period Servicing Asset At Amortized Cost, Amortization, Term Servicing Asset At Amortized Cost, Amortization, Term Recurring Basis Fair Value, Measurements, Recurring [Member] Derivative Financial Instruments Level 1 Level 2 Assets Total assets at fair value Assets, Fair Value Disclosure Liabilities Liabilities, Fair Value Disclosure [Abstract] Total liabilities at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Amortized Cost Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract] Due in 1 year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due in 1 to 5 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due in 5 to 10 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after 10 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Amortized Cost Estimated Fair Value Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract] Due in 1 year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due in 1 to 5 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due in 5 to 10 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after 10 years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Estimated Fair Value Estimated fair value of loans acquired Business Combination, Acquired Receivables, Gross Contractual Amount Loans held to maturity Business Combination, Acquired Receivable, Fair Value Amortized Cost Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] Due in 1 year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due in 1 to 5 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due in 5 to 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after 10 years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Total debt securities Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Mortgage and asset-backed securities Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Estimated Fair Value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Due in 1 year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due in 1 to 5 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due in 5 to 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Total debt securities Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value Mortgage and asset-backed securities Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Estimated Fair Value Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] Balance at beginning of period Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Original yield discount, net, at date of acquisition Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Additions Accretion Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion Reclassification from nonaccretable difference Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference Balance at end of period Changes in the Allowance for Loan and Leases Losses Allowance for Credit Losses on Financing Receivables [Table Text Block] Number of business segments Number of Reportable Segments Basis of Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Interest rate swaps Interest expense Interest Expense [Member] Other income Other Income [Member] Effective Portion, Recognized in OCI, Amount of Gain (Loss) Effective Portion, Reclassified from AOCI into Income, Amount of Gain (Loss) Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Ineffective Portion, Recognized in Income on Derivatives, Amount of Gain (Loss) Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Cash dividends per share preferred stock (in dollars per share) Preferred Stock, Dividends Per Share, Declared Cash dividends per share common stock (in dollars per share) Shares of common stock purchased (in shares) Treasury Stock, Shares, Acquired Shares of common stock issued (in shares) Stock Issued During Period, Shares, Treasury Stock Reissued Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Service charges and fees on deposit accounts Financial Services, Service Charges And Deposit Account Fees [Member] Financial Services, Service Charges And Deposit Account Fees [Member] Overdraft fees Financial Services, Overdraft Fees [Member] Financial Services, Overdraft Fees [Member] Customer service fees Financial Services, Customer Service Fees [Member] Financial Services, Customer Service Fees [Member] Credit card fee income Financial Services, Credit Card Fees [Member] Financial Services, Credit Card Fees [Member] Debit card income Financial Services, Debit Card Fees [Member] Financial Services, Debit Card Fees [Member] Other service charges Service, Other [Member] Total service charges and fees Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Service charges and fees Valuation adjustment on commercial servicing rights Other noninterest income Total noninterest income out-of-scope of Topic 606 Noninterest Income, Excluding Revenue From Contract With Customer Noninterest Income Excluding Revenue From Contract With Customer Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Fair Value, Other Assets Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Fair Value, Other Liabilities Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Schedule of Gross Carrying Amount and Accumulated Amortization of Other Intangible Assets Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block] Schedule of Estimated Future Amortization Expense of Amortizable Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Summary of Changes in Servicing Rights Servicing Asset at Amortized Cost [Table Text Block] Schedule of Servicing Asset at Fair Value and Amortized Cost Schedule of Servicing Asset at Fair Value and Amortized Cost [Table Text Block] Schedule of Servicing Asset at Fair Value and Amortized Cost [Table Text Block] Fair Value Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] Less than 12 months Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 12 months or longer Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Total Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value Unrealized Losses Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] Less than 12 months Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 months or longer Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss Schedule of Loans and Leases [Table] Schedule of Loans and Leases [Table] Schedule of Loans and Leases [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Loans and Finance Receivables Loans and Finance Receivables [Member] Citizens Finance Co Citizens Finance Co [Member] Citizens Finance Co [Member] Loans and Leases [Line Items] Loans and Leases [Line Items] Loans and Leases [Line Items] Gross loans receivable held to maturity Unearned discount