Investments, Debt and Equity Securities [Abstract] Investment securities available for sale Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Investment securities held to maturity Debt Securities, Held-to-maturity [Table Text Block] Amortized cost and fair values of investment securities available for sale by contractual maturity Investments Classified by Contractual Maturity Date [Table Text Block] Realized gains and losses and proceeds from sale Schedule of Realized Gain (Loss) [Table Text Block] Unrealized losses and fair value of available for sale and held to maturity securities, by investment category and time length Schedule of Unrealized Loss on Investments [Table Text Block] Receivables [Abstract] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Domain] Class of Financing Receivable, Type [Domain] Commercial and industrial Commercial And Industrial Financing Receivable [Member] Commercial and industrial financing receivable member. Commercial real estate — owner occupied Commercial Real Estate Owner Occupied Portfolio [Member] Commercial real estate owner occupied residential loans Commercial and business lending Commercial And Business Lending [Member] Commercial and business lending Commercial real estate — investor Commercial Real Estate Investor Portfolio Segment [Member] Commercial real estate - investor loans. Real estate construction Construction Loans [Member] Commercial real estate lending Commercial Real Estate Portfolio Segment [Member] Total commercial Commercial Portfolio Segment [Member] Residential mortgage Residential Mortgage [Member] Home equity Home Equity Line of Credit [Member] Other consumer Other consumer [Member] Installment. Total consumer Consumer Portfolio Segment [Member] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Pass Pass [Member] Special Mention Special Mention [Member] Potential Problem Potential Problem [Member] Potential problem. Nonaccrual Nonaccrual Loan [Member] Nonaccrual loan. Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment [Line Items] Loans and Leases Receivable, Net of Deferred Income Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Not Designated as Hedging Instrument, Economic Hedge [Member] Not Designated as Hedging Instrument, Economic Hedge [Member] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Interest Income [Member] Interest Income [Member] Other Operating Income (Expense) [Member] Other Operating Income (Expense) [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Business Combinations [Abstract] Estimated Fair Values of Assets Acquired and Liabilities Assumed Schedule of Business Acquisitions, by Acquisition [Table Text Block] Acquired loans fair value calculation Acquired loans fair value calculation [Table Text Block] Acquired loans fair value calculation [Table Text Block] Balance at beginning of period Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Purchases Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Additions Accretion Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion Net reclassification from non-accretable yield Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference Other(a) Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield Other Other increase or decrease in the aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans not accounted for as debt securities. End Balance Defined Benefit Plan [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Retirement Account Plan Pension Plan [Member] Postretirement Plan Other Postretirement Benefits Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] 2019 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2020 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2023 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2024 - 2028 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter Prior service cost Defined Benefit Plan Accumulated Other Comprehensive Income Net Prior Service Cost Credit Net Of Tax Net actuarial loss Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains (Losses) Net Of Tax Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive (income) loss Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Deposits [Abstract] Deposits, by Type [Abstract] Deposits, by Type [Abstract] Noninterest-bearing demand deposits Noninterest-bearing Domestic Deposit, Demand Savings Deposits, Savings Deposits Interest-bearing demand Deposits, Negotiable Order of Withdrawal (NOW) Money market Deposits, Money Market Deposits Brokered CDs Brokered Certificates Of Deposit Brokered certificates of deposit. Other time Other Time Deposits Other time deposits Total deposits Deposits Deposits by type Deposits By Type [TableText Block] Deposits by type [Table Text Block] Time deposits by maturity Time Deposits By Maturity [Table Text Block] Time Deposits By Maturity [Table Text Block] Income Tax Disclosure [Abstract] Effective Income Tax Rate Reconciliation Effective Income Tax Rate Reconciliation, Percent [Abstract] Federal income tax rate at statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Increases (decreases) resulting from: Increase decrease in effective income tax rate [Abstract] Tax-exempt interest and dividends Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent State income taxes (net of federal benefit) Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Bank owned life insurance Bank Owned Life Insurance 1 Bank owned life insurance Tax effect of tax credits and benefits, net of related expenses Effective Income Tax Rate Reconciliation, Tax Credit, Percent Tax reserve adjustments / settlements Increase (Decrease) in Tax Reserve Adjustments Increase (Decrease) in Tax Reserve Adjustments Net tax benefit from stock-based compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent Tax Cuts and Jobs Act impact on deferred remeasurement TCJA Impact Deferred Remeasurement TCJA Impact Deferred Remeasurement Tax planning in response to TCJA Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent FDIC premium FDIC premium FDIC premium Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Bank Mutual [Member] Bank Mutual [Member] Bank Mutual [Member] Oil and Gas Portfolio Segment [Member] Oil and Gas Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to oil and gas receivables. Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Line Items] Loans and Leases Receivable, Net of Deferred Income, Purchased Credit Impaired Loans And Covered Loans Loans and Leases Receivable, Net of Deferred Income, Purchased Credit Impaired Loans And Covered Loans Reflects the aggregate gross carrying amount of all categories of loans and leases held in portfolio which are purchased credit impaired and those whose losses will be shared with the Federal Deposit Insurance Corporation under loss sharing agreements before deducting the allowance for losses on loans and leases. Allowance for loan losses Loans and Leases Receivable, Allowance Percent of Loans Percent of Loans Percent of Loans Financing Receivable, Modifications, Post-Modification Recorded Investment Financing Receivable, Modifications, Post-Modification Recorded Investment Restructured Loans Subsequently Accruing Restructured Loans Subsequently Accruing Restructured Loans Subsequently Accruing Ytd Restructured Loans Still On Nonaccrual Ytd Restructured Loans Still On Nonaccrual Ytd Restructured Loans Still On Nonaccrual Loans and Leases Receivable, Impaired, Commitment to Lend Loans and Leases Receivable, Impaired, Commitment to Lend UnaccretedPurchaseDiscount UnaccretedPurchaseDiscount UnaccretedPurchaseDiscount UnaccretedPurchaseDiscount_PerformingLoans UnaccretedPurchaseDiscount_PerformingLoans Unaccreted Purchase Discount Performing Loans UnaccretedPurchaseDiscount_NonPerformingLoans UnaccretedPurchaseDiscount_NonPerformingLoans Unaccreted Purchase Discount NonPerforming Loans Fair Value Disclosures [Abstract] Closing Ratio Fair Value Inputs Closing Ratio Represents the percentage of loans currently in a lock position which management estimates will ultimately close. Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Capital market fees, net Capital Market Fees [Member] Capital market fees. Mortgage banking, net Mortgage Banking [Member] Interest rate-related instruments — customer and mirror Interest Rate Related Instruments Customer and Mirror [Member] Interest rate related instruments customer and mirror. Interest rate lock commitments (mortgage) Interest Rate Lock Commitments [Member] Forward commitments (mortgage) Forward Contracts [Member] Foreign currency exchange forwards Foreign Exchange Forward [Member] Commodity contracts Commodity Contract [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Gain (loss) on derivative instruments not designated as hedging instruments Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract] Gain / (Loss) Recognized in Income Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Derivative and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Segment Reporting, Measurement Disclosures [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Domain] Adjustments for Change in Accounting Principle [Domain] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Number of Reportable Segments Number of Reportable Segments Restructured Loans Subsequent Default [Table] Restructured Loans Subsequent Default [Table] Table showing troubled debt restructuring subsequent defaults by loan type Financing Receivable, Troubled Debt Restructuring [Axis] Class of Financing Receivable, Type of Borrower [Axis] Financing Receivable, Troubled Debt Restructuring [Domain] Class of Financing Receivable, Type of Borrower [Domain] Commercial and industrial Real estate construction Residential mortgage Residential Portfolio Segment [Member] Home equity Home Equity Port Folio Segments [Member] Home equity portfolio segments. Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of Loans Financing Receivable, Modifications, Subsequent Default, Number of Contracts Recorded Investment Financing Receivable, Modifications, Subsequent Default, Recorded Investment Regulatory Capital Requirements [Abstract] Regulatory Matters Regulatory Capital Requirements under Banking Regulations [Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Cash and due from banks Cash and Due from Banks Interest-bearing deposits in other financial institutions Interest-bearing Deposits in Banks and Other Financial Institutions Federal funds sold and securities purchased under agreements to resell Federal Funds Sold and Securities Purchased under Agreements to Resell Investment securities held to maturity, at amortized cost Debt Securities, Held-to-maturity Investment securities available for sale, at fair value Available-for-sale Securities Federal Home Loan Bank and Federal Reserve Bank stocks, at cost Federal Home Loan Bank Stock and Federal Reserve Bank Stock Residential loans held for sale Residential Loans Receivable Held-for-sale, Net, Not Part of Disposal Group Amount, after allowance for bad debt, of Residential loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities. Commercial loans held for sale Commercial Loans Receivable Held-for-sale, Net, Not Part of Disposal Group Amount, after allowance for bad debt, of Commercial loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities. Loans Allowance for loan losses Loans, net Loans and Leases Receivable, Net Amount Bank and corporate owned life insurance Bank and Corporate Owned Life Insurance The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (the bank or corporation) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy. Investment in unconsolidated subsidiaries Other Short-term Investments Trading assets Derivative Asset Premises and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Mortgage servicing rights, net Servicing Asset Other intangible assets, net Intangible Assets, Net (Excluding Goodwill) Other assets Other Assets Total assets Assets Liabilities and stockholders' equity Liabilities and Equity [Abstract] Interest-bearing deposits Interest-bearing Deposit Liabilities, Domestic Federal funds purchased and securities sold under agreements to repurchase Federal Funds Purchased and Securities Sold under Agreements to Repurchase Commercial Paper Other Short-term Borrowings FHLB Advances TotalFHLB_Advances Total FHLB_Advances Other long-term funding Other Long-term Debt Trading liabilities Derivative Liability Accrued expenses and other liabilities Other Liabilities Total liabilities Liabilities Stockholders’ equity (1) Stockholders' Equity Attributable to Parent [Abstract] Preferred equity Preferred Stock, Including Additional Paid in Capital Common stock Common Stock, Value, Issued Surplus Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury stock, at cost Treasury Stock, Value Total common equity Total Common Equity Total Common Equity Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Preferred shares issued Preferred Stock, Shares Issued Preferred shares authorized (par value $1.00 per share) Preferred Stock, Shares Authorized Common shares issued Common Stock, Shares, Issued Common shares authorized (par value $0.01 per share) Common Stock, Shares Authorized Treasury shares of common stock Treasury Stock, Shares Net Adjustment, Stock-based Compensation Plans, warrants, options, RSU/A (1) Net Adjustment, Stock-based Compensation Plans, warrants, options, RSU/A Net Adjustment, Stock-based Compensation Plans, warrants, options, RSU/A Schedule of Available-for-sale and Held-to-maturity Securities [Table] Schedule of Available-for-sale and Held-to-maturity Securities [Table] Schedule of Available-for-sale and Held-to-maturity Securities Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] FNMA / FHLMC Fannie Mae and Freddie Mac [Member] Fannie Mae and Freddie Mac [Member] GNMA Ginnie Mae [Member] Ginnie Mae [Member] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. Treasury securities US Treasury Securities [Member] Obligations of state and political subdivisions (municipal securities) US States and Political Subdivisions Debt Securities [Member] Residential Related Securities Residential Mortgage Backed Securities [Member] Private-label Mortgage-backed Securities, Issued by Private Enterprises [Member] GNMA commercial mortgage-related securities Commercial Mortgage Backed Securities [Member] FFELP asset backed securities Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] Debt Securities [Member] Debt Securities [Member] Equity securities Equity Securities [Member] Length Of Time Held To Maturity Securities Are In Continuous Unrealized Loss Position [Axis] Length Of Time Held To Maturity Securities Are In Continuous Unrealized Loss Position [Axis] Length of Time Held to Maturity Securities are In Continuous Unrealized Loss Positions [Domain] Length of Time Held to Maturity Securities are In Continuous Unrealized Loss Positions [Domain] Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member] Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member] Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member] Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member] Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] [Line Items] for Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Table] Unrealized losses and fair value of available for sale securities , by investment category and time length Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] Unrealized losses on available for sale securities, less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Unrealized losses on available for sale securities, 12 months or more Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total unrealized losses on available for sale securities Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Fair value of unrealized losses on available for sale securities, less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Fair value of unrealized losses on available for sale securities, 12 months or more Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Total fair value of unrealized losses on available for sale securities Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Number of available for sale securities in a continuous unrealized loss position less than twelve months Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year Number of available for sale securities in a continuous unrealized loss position for twelve months or more Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract] Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] Unrealized losses on held to maturity securities, less than 12 months Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months Unrealized losses on held to maturity securities, 12 months or more Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total unrealized losses on held to maturity securities Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss Fair value of unrealized losses on held to maturity securities, less than 12 months Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer Fair value of unrealized losses on held to maturity securities, 12 months or more Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Total fair value of unrealized losses on held to maturity securities Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value Number of held to maturity securities in a continuous unrealized loss position Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Retirement Benefits [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Minimum [Member] Minimum [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Performance-based Restricted Stock Award [Member] Performance-based Restricted Stock Award [Member] Performance-based Restricted Stock Award [Member] Service-based Restricted Stock Award [Member] Service-based Restricted Stock Award [Member] Service-based Restricted Stock Award [Member] Employee Stock Option [Member] Employee Stock Option [Member] Restricted Stock Award [Member] Restricted Stock Award [Member] Restricted Stock Award. Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2017 Incentive Compensation Plan [Member] 2017 Incentive Compensation Plan [Member] 2017 Incentive Compensation Plan [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Term of transfer restrictions Share-based Compensation Arrangement by Share-based Payment Award, Term of Transfer Restrictions Share-based Compensation Arrangement by Share-based Payment Award, Term of Transfer Restrictions Expiration term of awards Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Shares remaining available for grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Recognized compensation expense for accelerated vesting of stock options Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost Recognized compensation expense for vesting of stock options Allocated Share-based Compensation Expense String_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost String_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost String_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost Unvested share-based payment awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Year For Recognition Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Year For Recognition Employee service share based compensation nonvested awards total compensation cost not yet recognized year for recognition. Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Stock Based Compensation (Textuals) [Abstract] Stock Based Compensation (Textuals) [Abstract] Stock based compensation. Intrinsic value of stock options exercised InstrinsicValueOfStockOptionsExercised Intrinsic value represents the amount by which the fair market value of the underlying stock exceeds the exercise price of the stock option. Total fair value of vested stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Revenue Recognition [Abstract] Revenue Recognition, Multiple-deliverable Arrangements [Table] Revenue Recognition, Multiple-deliverable Arrangements [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Corporate and Commercial Specialty [Member] Corporate and Commercial Specialty [Member] Corporate and Commercial Specialty [Member] Community, Consumer and Business [Member] Community, Consumer and Business [Member] Community, Consumer and Business [Member] Risk Management and Shared Services [Member] Risk Management and Shared Services [Member] Risk Management and Shared Services [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Insurance Commissions and Fees [Member] Insurance Commissions and Fees [Member] Insurance Commissions and Fees [Member] Deposit Account [Member] Deposit Account [Member] Card-Based and No Loan Fees [Member] Card-Based and No Loan Fees [Member] Card-Based and No Loan Fees [Member] Fiduciary and Trust [Member] Fiduciary and Trust [Member] Brokerage Commission and Fees [Member] Brokerage Commission and Fees [Member] Brokerage Commission and Fees [Member] Other Revenue [Member] Other Revenue [Member] Other Revenue [Member] Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Noninterest Income In Scope of Topic 606 Noninterest Income In Scope of Topic 606 Noninterest Income In Scope of Topic 606 Noninterest Income, Outside of Scope of Topic 606 Noninterest Income, Outside of Scope of Topic 606 Noninterest Income, Outside of Scope of Topic 606 Total noninterest income Noninterest Income Accounting Policies [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] 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 Deposit Intangibles Core Deposits [Member] Other Intangibles Other Intangible Assets [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Asset, Useful Life Finite-Lived Intangible Asset, Useful Life Net period benefit cost for the pension and postretirement plans Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of actuarial loss (gain) Defined Benefit Plan, Amortization of Gain (Loss) Recognized settlement loss (gain) Defined Benefit Plan, Other Cost (Credit) Total net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Defined Benefit Plan, Interest Cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Defined Benefit Plan, Amortization of Gain (Loss) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Short-term Debt [Abstract] Schedule of Assets Sold under Agreements to Repurchase [Table] Schedule of Assets Sold under Agreements to Repurchase [Table] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Overnight and Continuous Maturity Overnight and on Demand [Member] Up to 30 days Maturity Less than 30 Days [Member] 30-90 days Maturity 30 to 90 Days [Member] Greater than 90 days Maturity Greater than 90 Days [Member] Agency mortgage-related securities Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Remaining Contractual Maturity of the Agreements Assets Sold under Agreements to Repurchase [Line Items] Repurchase agreements Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] Amount Recorded at Acquisition [Axis] Amount Recorded at Acquisition [Axis] Amount Recorded at Acquisition [Axis] Amount Recorded at Acquisition [Domain] Amount Recorded at Acquisition [Domain] [Domain] for Amount Recorded at Acquisition [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Allowance for Unfunded Commitments SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member] Change in the Allowance for Unfunded Commitments SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Balance at beginning of period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Provision for unfunded commitments Provision for Other Credit Losses Amount recorded at acquisition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Provision for Loan Losses Balance at end of period Recent Developments Details [Abstract] Recent Developments Details [Abstract] Recent Developments [Table] Recent Developments [Table] Recent Developments [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series C Preferred Stock Series C Preferred Stock [Member] Series D Preferred Stock Series D Preferred Stock [Member] Series E Preferred Stock Series E Preferred Stock [Member] Common Stock Common Stock [Member] Recent Developments [Line Items] Recent Developments [Line Items] [Line Items] for Recent Developments [Table] Common stock, dividends declared ($ per share) Common Stock, Dividends, Per Share, Declared Preferred stock, dividends declared ($ per share) Preferred Stock, Dividends Per Share, Declared Preferred Stock, Dividend Rate, Percentage Preferred Stock, Dividend Rate, Percentage Stock repurchase program authorized amount Stock Repurchase Program, Authorized Amount Remaining authorized repurchase amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Income Statement [Abstract] Statement [Table] Statement [Table] Risk Management and Shared Serivies [Member] Risk Management and Shared Serivies [Member] Risk Management and Shared Serivies Service charges and deposit account fees Card-Based and Loan Fees [Member] Card-Based and Loan Fees [Member] Card-Based and Loan Fees [Member] Trust and asset management fees Brokerage and advisory fees Statement [Line Items] Statement [Line Items] Interest income Interest and Dividend Income, Operating [Abstract] Interest and fees on loans Interest and Fee Income, Loans and Leases Interest and dividends on investment securities Interest and Dividend Income, Securities, by Taxable Status [Abstract] Taxable Interest Income, Securities, Operating, Taxable Tax-exempt Interest Income, Securities, Operating, Tax Exempt Other interest Other Interest and Dividend Income Total interest income Interest and Dividend Income, Operating Interest expense Interest Expense [Abstract] Interest on deposits Interest Expense, Deposits Interest on Federal funds purchased and securities sold under agreements to repurchase Interest Expense, Federal Funds Purchased and Securities Sold under Agreements to Repurchase Interest on other short-term funding Interest Expense, Other Short-term Borrowings Interest on FHLB advances Interest on FHLB Funding Interest on FHLB Funding Interest on long-term funding Interest Expense, Long-term Debt Total interest expense Interest Expense Net interest income Interest Income (Expense), Net Provision for credit losses Provision for Loan, Lease, and Other Losses Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Noninterest income Noninterest Income [Abstract] Service charges on deposit account fees Revenue from Contract with Customer, Including Assessed Tax Capital markets, net Capital Market Fees Net Capital market fees, net. Mortgage banking, net Fees and Commissions, Mortgage Banking and Servicing Bank and corporate owned life insurance Bank and Corporate Owned Life Insurance Income Earnings on or other increases in the value of the cash surrender value of bank and corporate owned life insurance policies. Asset gains (losses), net (a) Gain (Loss) on Disposition of Assets for Financial Service Operations Investment securities gains (losses), net Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments Other Noninterest Income, Other Operating Income Noninterest expense Noninterest Expense [Abstract] Personnel Labor and Related Expense Technology Information Technology and Data Processing Occupancy Occupancy, Net Business development and advertising Marketing and Advertising Expense Equipment Equipment Expense Legal and professional Legal And Professional Fees Legal and professional fees. Card issuance and loan costs Loan Expense Loan Expense Foreclosure / OREO expense, net Foreclosed Real Estate Expense FDIC assessment Federal Deposit Insurance Corporation Premium Expense Other intangible amortization Amortization of Intangible Assets Acquisition related costs (b) Business Combination, Acquisition Related Costs Other Other Noninterest Expense Total noninterest expense Noninterest Expense Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Preferred stock dividends Preferred Stock Dividends and Other Adjustments Net income available to common equity Net Income (Loss) Available to Common Stockholders, Basic Earnings per common share Earnings Per Share [Abstract] Basic Earnings Per Share, Basic Diluted Earnings Per Share, Diluted Average common shares outstanding Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Tax planning in response to TCJA Fair Value Measurements Fair Value Disclosures [Text Block] Earnings Per Share Textuals [Abstract] Earnings per share. Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Common Stock Warrant [Member] Warrant [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Deposits Deposit Liabilities Disclosures [Text Block] Document And Entity Information [Abstract] Document And Entity Information. Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Property, Plant and Equipment [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Payments, 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months Payments, 2020 Operating Leases, Future Minimum Payments, Due in Two Years Payments, 2021 Operating Leases, Future Minimum Payments, Due in Three Years Payments, 2022 Operating Leases, Future Minimum Payments, Due in Four Years Payments, 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Operating Leases, Future Minimum Payments Receivable [Abstract] Operating Leases, Future Minimum Payments Receivable [Abstract] Receipts, 2019 Operating Leases, Future Minimum Payments Receivable, Current Receipts, 2020 Operating Leases, Future Minimum Payments Receivable, in Two Years Receipts, 2021 Operating Leases, Future Minimum Payments Receivable, in Three Years Receipts, 2022 Operating Leases, Future Minimum Payments Receivable, in Four Years Receipts, 2023 Operating Leases, Future Minimum Payments Receivable, in Five Years Thereafter Operating Leases, Future Minimum Payments Receivable, Thereafter Total Operating Leases, Future Minimum Payments Receivable Commitments and Contingencies Disclosure [Abstract] Mortgage Repurchase Reserve Mortgage Repurchase Reserve [Member] Summary of changes in the residential mortgage repurchase reserve [Line Items] ValuationAndQualifyingAccoun [Line Items] Residential mortgage repurchase reserve Repurchase provision expense SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Adjustments to provision expense SEC Schedule, 12-09, Valuation Allowances and Reserves, Period Increase (Decrease) Charge offs, net SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Amount recorded at acquisition SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Balance sheet category and fair values of derivative instruments not designated as hedging instruments Summary Of Derivative Instruments Not Designated As Hedging Instruments [Table Text Block] Summary of derivative instruments not designated as hedging instruments. Balance Sheet Recording of Fair Value Hedge [Table Text Block] Balance Sheet Recording of Fair Value Hedge [Table Text Block] [Table Text Block] for Balance Sheet Recording of Fair Value Hedge [Table] Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Gain (loss) on derivative instruments not designated as hedging instruments Schedule Of Derivative Instruments Gain Loss Not Designated As Hedging Instruments [Table Text Block] Schedule of derivative instruments gain loss not designated as hedging instruments. Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Acquired Performing Loans Purchased Performing Loans [Member] Purchased Performing Loans [Member] Acquired Impaired Loans Purchase Credit Impaired Loans [Member] Purchase Credit Impaired Loans [Member] BKMU Assets Acquired Liabilities Assumed [Member] BKMU Assets Acquired Liabilities Assumed [Member] BKMU Assets Acquired Liabilities Assumed [Member] Financing Receivable Financing Receivable, Impaired [Line Items] Contractual required principal and interest at acquisition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition Contractual cash flows not expected to be collected (nonaccretable discount) Certain Loans Acquired in Transfer, Nonaccretable Difference Expected cash flows at acquisition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition Interest component of expected cash flows (accretable discount) Fair value of acquired loans Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value Subordinated Borrowing [Table] Subordinated Borrowing [Table] Subordinated Borrowing [Axis] Subordinated Borrowing [Axis] Subordinated Borrowing, Name [Domain] Subordinated Borrowing, Name [Domain] Two Thousand Eighteen Senior Notes [Member] [Domain] Two Thousand Eighteen Senior Notes [Member] [Domain] Two Thousand Eighteen Senior Notes [Member] [Domain] Two Thousand Fourteen Senior Notes [Member] Two Thousand Fourteen Senior Notes [Member] Two Thousand Fourteen Senior Notes [Member] Two Thousand Fourteen Subordinated Notes [Member] Two Thousand Fourteen Subordinated Notes [Member] Two Thousand Fourteen Subordinated Notes [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] FHLB, Increase in Advances [Domain] FHLB, Increase in Advances [Domain] FHLB, Increase in Advances [Domain] FLHB Advances, Putable [Domain] FLHB Advances, Putable [Domain] FLHB Advances, Putable [Domain] Subordinated Borrowing [Line Items] Subordinated Borrowing [Line Items] Collateral for repurchase agreements Carrying Value of Securities Purchased under Agreements to Resell and Deposits Paid for Securities Borrowed New Senior Debt Issued New Senior Debt Issued New Senior Debt Issued Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Junior Subordinated Debentures Issued Junior Subordinated Debentures Issued Junior subordinated debentures issued. Debt Instrument, Term Debt Instrument, Term Subordinated Borrowing, Interest Rate Subordinated Borrowing, Interest Rate Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Offsetting [Abstract] Balance Sheet Offsetting Balance Sheet Offsetting Disclosure [Text Block] Balance Sheet Offsetting Disclosure Statement of Cash Flows [Abstract] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income 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, Nonproduction Addition to (recovery of) valuation allowance on mortgage servicing rights, net Mortgage Servicing Rights (MSR) Impairment (Recovery) Amortization of mortgage servicing rights Amortization of Mortgage Servicing Rights (MSRs) Amortization of other intangible assets Amortization and accretion on earning assets, funding, and other, net Accretion (Amortization) of Discounts and Premiums, Investments Net amortization of tax credit investments Other Depreciation and Amortization Deferred income taxes Deferred Income Tax Expense (Benefit) Losses (gains) on sales of investment securities, net Marketable Securities, Gain (Loss) Asset (gains) losses, net (Gain) loss on mortgage banking activities, net Gain (Loss) on Sale of Mortgage Loans Mortgage loans originated and acquired for sale Payments for Origination and Purchases of Loans Held-for-sale Proceeds from sales of mortgage loans held for sale Proceeds from Sale of Mortgage Loans Held-for-sale Pension contributions Payment for Pension Benefits (Increase) decrease in interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Increase (decrease) in interest payable Increase (Decrease) in Interest Payable, Net Increase (Decrease) Cash Collateral from Counterparties Increase (Decrease) Cash Collateral from Counterparties Net change in other assets and other liabilities 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] Net increase in loans Payments for (Proceeds from) Loans and Leases Purchases of Payments for Investing Activities [Abstract] Available for sale securities Payments to Acquire Available-for-sale Securities Held to maturity securities Payments to Acquire Held-to-maturity Securities Federal Home Loan Bank and Federal Reserve Bank stocks Payments to Acquire Federal Home Loan Bank Stock Premises, equipment, and software, net of disposals Payments for (Proceeds from) Productive Assets Proceeds from Proceeds from Investing Activities [Abstract] Sales of available for sale securities Proceeds from Sale of Available-for-sale Securities Sale of Federal Home Loan Bank and Federal Reserve Bank stocks Proceeds from Sale of Federal Home Loan Bank Stock Prepayments, calls, and maturities of available for sale investment securities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Prepayments, calls, and maturities of held to maturity investment securities Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Sales, prepayments, calls and maturities of other assets Proceeds from Maturities, Prepayments and Calls of Other Investments Net change in tax credit and alternative investments Net Change in Tax Credit Investments The net cash outflow or inflow from changes in tax credit investments. Net cash (paid) received in acquisition Payments to Acquire Businesses, Net of Cash Acquired Net cash used in 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 (decrease) in deposits Increase (Decrease) in Deposits Net increase (decrease) in short-term funding Proceeds from (Repayments of) Short-term Debt Net increase (decrease) in short-term FHLB advances Proceeds from (Repayment of) short-term FHLB Advances Proceeds from (Repayment of) short-term FHLB Advances Repayment of long-term FHLB advances Repayment of FHLB Advance Repayment of FHLB Advance Proceeds from long-term FHLB advances Proceeds from FHLB Advance Proceeds from FHLB Advance Repayment of long-term funding Repayments of Long-term Debt Proceeds from issuance of long-term funding Proceeds from Issuance of Long-term Debt Proceeds from issuance of preferred shares Proceeds from Issuance of Preferred Stock and Preference Stock Proceeds from issuance of common stock for stock-based compensation plans Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Redemption of preferred shares Payments for Repurchase of Redeemable Preferred Stock Redemption of warrants Payments for Repurchase of Warrants Purchase of preferred shares Payments for Repurchase of Preferred Stock and Preference Stock Purchase of common stock returned to authorized but unissued Payments for returned to authorized but unissued common stock Purchase of treasury stock payments for repurchase of common stock for tax withholding The cash outflow for repurchase of common stock for tax withholding Cash dividends on common stock Payments of Ordinary Dividends, Common Stock Cash dividends on preferred stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Cash, cash equivalents, and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash at end of period Supplemental disclosures of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid for income and franchise taxes Income Taxes Paid, Net Loans and bank premises transferred to other real estate owned Real Estate Owned, Transfer to Real Estate Owned Capitalized mortgage servicing rights Servicing Asset at Fair Value, Additions Loans transferred into held for sale from portfolio, net Transfer of Portfolio Loans and Leases to Held-for-sale Acquisition Supplemental Cash Flow - Acquisition Information [Abstract] Supplemental Cash Flow - Acquisition Information [Abstract] Fair value of assets acquired, including cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets Fair value ascribed to goodwill and intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Including Goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Including Goodwill Fair value of liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Common stock issued in acquisition Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Cash and cash equivalents Cash Equivalents, at Carrying Value Restricted Cash Restricted Cash Investment Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Gross gains on available for sale securities Debt Securities, Available-for-sale, Realized Gain Gross gains on held to maturity securities Debt Securities, Held-to-maturity, Sold, Realized Gain Debt Securities, Held-to-maturity, Sold, Realized Gain Total gains Debt Securities, Trading, Realized Gain Gross losses on available for sale securities Debt Securities, Available-for-sale, Realized Loss Gross losses on held to maturity securities Debt Securities, Held-to-maturity, Sold, Realized Loss Debt Securities, Held-to-maturity, Sold, Realized Loss Total losses Debt Securities, Trading, Realized Loss Investment securities gains, net Debt Securities, Realized Gain (Loss) Proceeds from sales of investment securities Proceeds from Sale and Maturity of Marketable Securities Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Summary of activity in accumulated other comprehensive income (loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Required minimum cash and reserve balances Cash and Securities Segregated under Federal and Other Regulations Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Operating Segments Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Segment Income Statement Data Abstract Segment Reporting Information, Profit (Loss) [Abstract] Net interest income Net intersegment interest income (expense) Net intersegment interest income (expense) Net intersegment interest income (expense) Segment net interest income Segment net interest income Segment net interest income Noninterest income Total revenue Revenues Credit provision (a) Noninterest expense Income (loss) before income taxes Income tax expense (benefit) Return on average allocated capital (ROCET1) (b) Return on average allocated capital Return on average allocated tier 1 common equity Segment Balance Sheet Data Segment Balance Sheet Data [Abstract] Segment Reporting Information Average earning assets Average earning assets Average earning assets Average loans Average Loans Average Loans Average deposits Average deposits Average deposits Average allocated capital (CETI)(b) Average allocated capital Average allocated tier 1 common equity Allocated goodwill Allocated Goodwill - Segment Allocated Goodwill - Segment Business Combination, Acquisition Related Costs Gain (Loss) on Disposition of Assets for Financial Service Operations FHLB Maturity Schedule Disclosure [Abstract] FHLB Maturity Schedule Disclosure [Abstract] FHLB_Maturity_ [Table] FHLB_Maturity_ [Table] FHLB_Maturity_ [Table] Maturity or put date 1 year or less FHLB Maturity within One Year [Domain] FHLB Maturity within One Year [Domain] After 1 but within 2 FHLB Maturity One Year to Two Years [Domain] FHLB Maturity One Year to Two Years [Domain] After 2 but within 3 FHLB Maturity Over Two Years to Three Years [Domain] FHLB Maturity Over Two Years to Three Years [Domain] After 3 years FHLB Maturity Over Three Years [Domain] FHLB Maturity Over Three Years [Domain] FHLB_Maturity_ [Line Items] FHLB_Maturity_ [Line Items] [Line Items] for FHLB_Maturity_ [Table] Weighted Average Coupon Rate FHLB Weighted Average Coupon Rate FHLB Weighted Average Coupon Rate Condensed Financial Information Disclosure [Abstract] Condensed Financial Statements [Table] Condensed Financial Statements [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Company Only Parent Company [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Interest-bearing Deposits in Banks and Other Financial Institutions Notes and interest receivable from subsidiaries Notes Receivable, Related Parties, Noncurrent Investments in and receivable due from subsidiaries Investments in and Receivable Due from Subsidiaries Represents intercompany ownership interest in bank and nonbank subsidiaries Commercial paper Commercial Paper Senior notes, at par Senior Notes Subordinated notes, at par Subordinated Debt Long-term funding capitalized costs Other Long-term Debt and Capitalized Costs Other Long-term Debt and Capitalized Costs Total long-term funding Long-term Debt Accrued expenses and other liabilities Common equity Schedule Of Financing Receivable Troubled Debt Restructuring [Table] Schedule Of Financing Receivable Troubled Debt Restructuring [Table] Subsequent redefault table Number of Loans Financing Receivable, Modifications, Number of Contracts Recorded Investment Unpaid Principal Balance Financing Receivable, Modifications, Pre-Modification Recorded Investment Retirement Account Plan Prior to Merger [Member] Retirement Account Plan Prior to Merger [Member] Retirement Account Plan Prior to Merger [Member] Other Pension Plan [Member] Other Pension Plan [Member] Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Expected long-term rate of return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Retirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Calculations for basic and diluted earnings per common share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Trading assets Trading Assets [Member] Trading liabilities Trading Liabilities [Member] Other assets Other Assets [Member] Other liabilities Other Liabilities [Member] Purchased options (time deposit) Purchased Deposit Option [Member] A purchased deposit option with an equity indexed derivative Written options (time deposit) Written Deposit Options [Member] Written deposit option with an equity indexed derivative interest rate product [Member] interest rate product [Member] interest rate product [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Derivative Instruments Not Designated as Hedging Instruments [Abstract] Derivative Instruments Not Designated as Hedging Instruments [Abstract] Notional Amount Derivative, Notional Amount Fair Value Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net Derivative, Fair Value, Net Derivative, Fair Value, Net Schedule Of Lending Related And Other Commitments [Table] Schedule Of Lending Related And Other Commitments [Table] Schedule Of Lending Related And Other Commitments. Lending-related commitments by type [Axis] Lending-related commitments by type [Axis] Lending related commitments by type. Lending Related Commitments By Type [Domain] Lending Related Commitments By Type [Domain] Lending related commitments by type. Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale Commitments to Extend Credit [Member] Commercial Letters Of Credit Commercial Letters Of Credit [Member] Commercial letters of credit. Standby Letters of Credit Standby Letters of Credit [Member] Schedule of lending-related and other commitments [Line Items] Schedule of lending-related and other commitments [Line Items] Schedule of lending-related and other commitments. Lending related commitments, fair value LendingRelatedCommitments, FairValue Lending Related Commitments, Fair Value Summary of lending-related and other commitments Lending Related And Other Commitments [Abstract] Lending related and other commitments. Lending related commitments Lending Related Commitments Lending related commitments. Standby letters of credit, fair value Lines of Credit, Fair Value Disclosure Short and Long-term funding Schedule of Short-term Debt [Table Text Block] Schedule of Repurchase Agreements Schedule of Repurchase Agreements [Table Text Block] FHLB_Maturity_ [Table Text Block] FHLB_Maturity_ [Table Text Block] [Table Text Block] for FHLB_Maturity_ [Table] Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Maturities of Long-term Debt [Table Text Block] Restructuring and Related Activities [Abstract] Recent Developments Subsequent Events [Text Block] Disaggregation of Revenue [Table Text Block] Disaggregation of Revenue [Table Text Block] Revenue Recognition 606 [Text Block] Revenue Recognition 606 [Text Block] Revenue Recognition 606 [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Business and Basis of Financial Statement Presentation Basis of Accounting, Policy [Policy Text Block] Business Combinations Business Combinations Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Investment Securities Marketable Securities, Policy [Policy Text Block] Federal Home Loan Bank (FHLB) and Federal Reserve Bank Stocks Federal Home Loan Bank and Federal Reserve Bank Stocks [Policy Text Block] Federal Home Loan Bank ("FHLB") and Federal Reserve Bank Stocks Policy Loans Held for Sale Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block] Loans Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block] Troubled Debt Restructurings (Restructured Loans) Loans and Leases Receivable, Troubled Debt Restructuring Policy [Policy Text Block] Allowance for Loan Losses Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] Other Real Estate Owned Loans and Leases Receivable, Real Estate Acquired Through Foreclosure, Policy [Policy Text Block] Reserve for Unfunded Commitments Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Premises and Equipment and Software Property, Plant and Equipment, Policy [Policy Text Block] Goodwill and Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Mortgage Servicing Rights Transfers and Servicing of Financial Assets, Servicing of Financial Assets, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Derivative and Hedging Activities Derivatives, Policy [Policy Text Block] Securities Sold Under Agreement to Repurchase Repurchase and Resale Agreements Policy [Policy Text Block] Retirement Plan Pension and Other Postretirement Plans, Policy [Policy Text Block] Stock-Based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Earnings Per Common Share Earnings Per Share, Policy [Policy Text Block] New Accounting Pronouncements Adopted New Accounting Pronouncements, Policy [Policy Text Block] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance at beginning of year Unrecognized Tax Benefits Subtractions for tax positions related to prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Subtractions for settlements with tax authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Additions for tax positions related to current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Balance at end of year Current and Deferred Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Valuation Allowance [Table Text Block] Summary of Valuation Allowance [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Summary Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Fixed income securities Investment securities available for sale Debt Securities, Available-for-sale [Abstract] 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 Fair Value Debt Securities, Held-to-maturity [Abstract] Debt Securities, Held-to-maturity [Abstract] Amortized Cost Gross Unrealized Gains Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain Held-to-maturity, Gross Unrealized Loss Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss Fair Value Debt Securities, Held-to-maturity, Fair Value Selected segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Equity [Abstract] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Subsidiary equity balance Subsidiary Equity Balance Subsidiary Equity Balance Class Of Stock [Table] Class Of Stock [Table] information about different classes of stock Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Treasury Stock Treasury Stock, Common [Member] Class of Stock [Line Items] Class of Stock [Line Items] Depositary shares issued (in shares) Depositary Shares Issued Depositary shares issued in perpetual preferred stock Liquidation preference on depositary shares (in usd per share) Liquidation Preference On Depositary Shares Liquidation preference on depositary shares issued of perpetual preferred stock Preferred Stock, Redemption Terms Preferred Stock, Redemption Terms Redemption Price On Depositary Shares Redemption Price On Depositary Shares Redemption Price On Depositary Shares Depositary share value (in usd per share) Depositary Share Per Share Value Depositary share per share value in perpetual preferred stock Purchase of stock, value Stock Repurchased During Period, Value Stock Repurchased During Period, Shares Stock Repurchased During Period, Shares Remaining authorized repurchase amount Warrants to purchase shares of common stock (in shares) Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants Term of warrants Class of Warrant or Right, Term Class of Warrant or Right, Term Exercise price of warrants (in usd per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Class of Warrant or Right, Outstanding Class of Warrant or Right, Outstanding Shares from Warrant Exercises Shares from Warrant Exercises Shares from Warrant Exercises Unexercised Warrants, Expired Shares Unexercised Warrants, Expired Shares Unexercised Warrants, Expired Shares Treasury stock shares acquired (in shares) Treasury Stock, Shares, Acquired Treasury stock carrying basis Treasury Stock, Carrying Basis Treasury stock acquired average cost per share (in usd per share) Treasury Stock Acquired, Average Cost Per Share Treasury Stock, Shares, Retired Treasury Stock, Shares, Retired Treasury Stock, Retired, Cost Method, Amount Treasury Stock, Retired, Cost Method, Amount Repurchased amount for minimum tax withholding settlement Payments Related to Tax Withholding for Share-based Compensation Repurchased shares for minimum tax withholding settlements (in shares) Shares Paid for Tax Withholding for Share Based Compensation Minimum tax withholding settlement average cost per share (in usd per share) Minimum Tax Withholding Settlement Average Cost Per Share Depository share ratio Preferred Stock, Conversion Ratio to Depository Shares Preferred Stock, Conversion Ratio to Depository Shares Commercial and business lending Commercial real estate lending Commercial Real Estate Lending [Member] Commercial real estate loans Total commercial Commercial Financing Receivable [Member] Commercial financing receivable member. Home equity Total consumer Consumer Loan [Member] Loans with a related allowance Loans With Related Allowance [Member] Loans with a related allowance. Loans with no related allowance Loans With No Related Allowance [Member] Loans with no related allowance. Financing Receivable, Impaired [Line Items] Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans Loan and Lease Receivables, Impaired [Abstract] Recorded Investment Impaired Financing Receivable, Recorded Investment Unpaid Principal Balance Impaired Financing Receivable, Unpaid Principal Balance Related Allowance Impaired Financing Receivable, Related Allowance Average Recorded Investment Impaired Financing Receivable, Average Recorded Investment Interest Income Recognized Impaired Financing Receivable, Interest Income, Accrual Method Net Recorded Investment of the Impaired Loans Net Recorded Investment of the Impaired Loans Net Recorded Investment of the Impaired Loans Time Deposits, Fiscal Year Maturity [Abstract] Time Deposits, Fiscal Year Maturity [Abstract] 2019 Time Deposit Maturities, Next Twelve Months 2020 Time Deposit Maturities, Year Two 2021 Time Deposit Maturities, Year Three 2022 Time Deposit Maturities, Year Four 2023 Time Deposit Maturities, Year Five Thereafter Time Deposit Maturities, after Year Five Total Time Deposits Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities Commitments and Contingencies Disclosure [Text Block] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] 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] Summarized details of Loans Summarized Details Of Loans [Abstract] Summarized details of Loans. Current Financing Receivable, Recorded Investment, Current Total Past Due Financing Receivable, Recorded Investment, Past Due Financing Receivable, Recorded Investment, Nonaccrual Status Financing Receivable, Recorded Investment, Nonaccrual Status Nonaccrual Loans, Current Portion Nonaccrual Loans, Current Portion Nonaccrual Loans, Current Portion Percent of current nonaccrual loans Percent of current nonaccrual loans Premises and Equipment Property, Plant and Equipment Disclosure [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Reporting Comprehensive Income(2018-02) Reporting Comprehensive Income(2018-02) Reporting Comprehensive Income(2018-02) Expense Reclass (asu 2017-07) Expense Reclass (asu 2017-07) Expense Reclass (asu 2017-07) Visa Restricted Shares Owned Visa Restricted Stock Owned Visa Restricted Stock Owned 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] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 Fair Value, Inputs, Level 3 [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] FNMA / FHLMC GNMA Private-label GNMA commercial mortgage-related securities Federal Family Education Loan Program (FFELP) Guaranteed Loans Other securities (debt and equity) Other Debt And Other Equity Securities [Member] Other debt and other equity securities. Total investment securities available for sale Available-for-sale Securities [Member] Residential Loans Held For Sale Member [Member] Residential Loans Held For Sale Member [Member] Residential Loans Held For Sale Member Commercial loans held for sale [Domain] Commercial loans held for sale [Domain] Commercial loans held for sale [Domain] Interest rate-related instruments Foreign currency exchange forwards Interest rate lock commitments to originate residential mortgage loans held for sale Forward commitments to sell residential mortgage loans Commodity contracts Purchased options (time deposit) 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] Assets, Fair Value Disclosure [Abstract] Assets, Fair Value Disclosure [Abstract] Investment securities available for sale Trading Assets Liabilities, Fair Value Disclosure [Abstract] Liabilities, Fair Value Disclosure [Abstract] Interest Rate Fair Value Hedge Asset at Fair Value Interest Rate Fair Value Hedge Asset at Fair Value Loans Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Investment securities and cash equivalents pledged as collateral Additional Collateral, Aggregate Fair Value Derivative collateral right to reclaim cash Derivative, Collateral, Right to Reclaim Cash Federal funds purchased Federal Funds Purchased Securities sold under agreements to repurchase Securities Sold under Agreements to Repurchase Federal funds purchased and securities sold under agreements to repurchase Total short-term funding Short-term Debt Senior notes, at par Subordinated notes, at par Other long-term funding and capitalized costs Other Long-term Debt Total short and long-term funding, excluding FHLB advances TotalShortTermLongTermExcludingFHLB Total Short Term Long Term Excluding FHLB Short-term FHLB advances ShortTermFHLBAdvances Short-Term FHLB Advances Long-term FHLB advances LongTermFHLBAdvances Long-Term FHLB Advances Total FHLB advances Total short and long-term funding Debt, Long-term and Short-term, Combined Amount Schedule Of Financing Receivable Table [Table] Schedule Of Financing Receivable Table [Table] Schedule Of Financing Receivable Table [Table] Commercial real estate - owner occupied Total consumer Loans and Leases Receivable Disclosure [Line Items] Loans and Leases Receivable Disclosure [Line Items] Purchased credit-impaired loans Current: Current Income Tax Expense (Benefit) [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit) Deferred: Deferred Income Tax Expense (Benefit) [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Total deferred Total income tax expense Offsetting Assets [Table] Offsetting Assets [Table] Interest Rate Contract Interest Rate Contract [Member] Offsetting Assets [Line Items] Offsetting Assets [Line Items] Offsetting Derivative Assets [Abstract] Offsetting Derivative Assets [Abstract] Gross amounts of recognized assets Derivative Asset, Fair Value, Gross Asset Gross amounts offset in the balance sheet Derivative Asset, Fair Value, Gross Liability Net amounts presented in the balance sheet Derivative Asset, Fair Value, Amount Not Offset Against Collateral Derivative liability available for offset Derivative, Collateral, Obligation to Return Securities Collateral received Derivative Asset, Fair Value of Collateral Net amount Derivative Asset, Fair Value, Amount Offset Against Collateral Offsetting Liabilities [Table] Offsetting Liabilities [Table] Offsetting Liabilities [Line Items] Offsetting Liabilities [Line Items] Offsetting Derivative Liabilities [Abstract] Offsetting Derivative Liabilities [Abstract] Gross amounts of recognized liabilities Derivative Liability, Fair Value, Gross Liability Gross amounts offset in the balance sheet Derivative Liability, Fair Value, Gross Asset Net amounts presented in the balance sheet Derivative Liability, Fair Value, Amount Not Offset Against Collateral Derivative asset available for offset Derivative, Collateral, Right to Reclaim Securities Collateral pledged Derivative Liability, Fair Value of Collateral Net amount Derivative Liability, Fair Value, Amount Offset Against Collateral Gross deferred tax assets: Deferred Tax Assets, Gross [Abstract] Allowance for loan losses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Allowance for other losses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Accrued liabilities Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Benefit of tax loss and credit carryforwards Deferred Tax Assets, Other Loss Carryforwards Nonaccrual interest Nonaccrual interest Nonaccrual interest Net unrealized losses on available-for-sale securities Other Comprehensive Income, Available-for-sale Securities, Tax Unrealized Other Comprehensive Income Available For Sale Securities Tax Unrealized Net unrealized losses on pension and postretirement benefits Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect Unrealized Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect Unrealized Other Deferred Tax Assets, Other Total deferred tax assets Deferred Tax Assets, Gross Valuation allowance for deferred tax assets Deferred Tax Assets, Valuation Allowance Total deferred tax assets after valuation allowance Deferred Tax Assets, Net of Valuation Allowance Gross deferred tax liabilities Deferred Tax Liabilities, Gross [Abstract] Prepaid expenses Deferred Tax Liabilities, Prepaid Expenses Goodwill Deferred Tax Liabilities, Goodwill and Intangible Assets Mortgage banking activities Deferred Tax Liabilities, Mortgage Servicing Rights Deferred loan fee income Deferred loan fee income Deferred loan fee income State deferred taxes State income taxes State income taxes Lease financing Deferred Tax Liabilities, Leasing Arrangements Bank premises and equipment DeferredTaxLiabilityDepreciation Deferred Tax Liability Deprecation Purchase accounting Purchase accounting Purchase accounting Other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Net Net deferred tax assets Deferred Tax Assets, Net Earnings Per Common Share Earnings Per Share [Text Block] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Group Annuity Contracts [Member] Group Annuity Contracts [Member] Group Annuity Contracts [Member] Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Fair value of group annuity contract at February 1, 2018 (date of Bank Mutual acquisition) DefinedBenefitPlanFairValueOfPlanAssetsGroupAnnuityContracts DefinedBenefitPlanFairValueOfPlanAssetsGroupAnnuityContracts Actual return on plan assets Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held Transfers from money market funds and equity securities Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3 Benefits paid Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decrease for Settlement Fair value of group annuity contract at December 31, 2018 Defined Benefit Plan, Plan Assets, Amount Short and Long-term Funding Short-term Debt [Text Block] Summary of Premises and Equipment Property, Plant and Equipment [Table Text Block] Minimum annual rentals and commitments under noncancelable operating leases Lessee, Operating Lease, Disclosure [Table Text Block] Statement of Stockholders' Equity [Abstract] Preferred Equity Preferred Stock [Member] Surplus Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] AOCI Allocated to Parent [Member] AOCI Allocated to Parent [Member] AOCI Allocated to Parent [Member] Accumulated Other Comprehensive Income (Loss) Treasury Stock Treasury Stock [Member] Net Adjustment, Stock-based Compensation Plans, warrants, options, RSU/A Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance Preferred stock shares outstanding, beginning balance (in shares) Preferred Stock, Shares Outstanding Common stock shares outstanding, beginning balance (in shares) Common Stock, Shares, Outstanding Comprehensive income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Net income Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income, Other, Net of Tax Other Comprehensive Income, Other, Net of Tax Adoption of new accounting standards New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Common stock issued: Common Stock Issued [Abstract] Common stock issued. Stock-based compensation plans, net Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Stock Issued During Period, Shares, Acquisitions Stock Issued During Period, Value, Acquisitions Purchase of common stock returned to authorized but unissued Stock Repurchased and Retired During Period, Shares Purchase of common stock returned to authorized but unissued Stock Repurchased and Retired During Period, Value Purchase of treasury stock Treasury Stock, Value, Acquired, Cost Method Cash dividends Dividends [Abstract] Common stock dividends Dividends, Common Stock, Cash Preferred stock dividends Dividends, Preferred Stock, Cash Issuance of preferred stock Stock Issued During Period, Shares, New Issues Issuance of preferred stock Stock Issued During Period, Value, New Issues Redemption of preferred stock Stock Redeemed or Called During Period, Shares Redemption of preferred stock Stock Redeemed or Called During Period, Value Purchase of preferred stock Purchase of preferred stock Proceeds from Warrant Exercises Proceeds from Warrant Exercises Stock-based compensation expense, net Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Tax impact of stock-based compensation Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Tax Act Reclassification Tax Act Reclassification Tax Act Reclassification Change in Equity Securities(2016-01) Change in Equity Securities(2016-01) Change in Equity Securities(2016-01) Other Stockholders' Equity, Other Shares Other Stockholders' Equity, Other Ending balance Preferred stock shares outstanding, ending balance (in shares) Common stock shares outstanding, ending balance (in shares) Financing Receivable, Allowance for Credit Losses [Roll Forward] Financing Receivable, Allowance for Credit Losses [Roll Forward] Balance at beginning of year Charge offs Allowance for Loan and Lease Losses, Write-offs Recoveries Allowance for Loan and Lease Loss, Recovery of Bad Debts Net charge offs Allowance for Loan and Lease Losses Write-offs, Net Provision for Loan Losses Provision for Loan and Lease Losses Balance at end of period Allowance for loan losses Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] Individually evaluated Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Collectively evaluated Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Loans Loans [Abstract] Loans. Individually evaluated Financing Receivable, Individually Evaluated for Impairment Collectively evaluated Financing Receivable, Collectively Evaluated for Impairment INCOME Revenues [Abstract] Dividends from subsidiaries SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries Interest income on notes receivable from subsidiaries Other income Other Operating Income Total income EXPENSE Operating Expenses [Abstract] Interest expense on short and long-term funding Interest Expense, Debt Other expense Other Expenses Total expense Operating Expenses Income before income tax expense (benefit) and equity in undistributed net income (loss) of subsidiaries Income before equity in undistributed net income (loss) of subsidiaries Income Loss From Continuing Operations Before Income Loss From Equity Method Investments Income Loss From Continuing Operations Before Income Loss From Equity Method Investments Equity in undistributed net income (loss) of subsidiaries Equity In Undistributed net Income (loss) of subsidiaries Equity In Undistributed net Income (loss) of subsidiaries Preferred stock dividends Net actuarial gain (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Amortization of actuarial loss (gain) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Plan amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment ASU Adjustment RAP (2018-02) ASU Adjustment RAP (2018-02) ASU Adjustment RAP (2018-02) Income tax (expense) benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Other comprehensive income (loss) on pension and postretirement obligations Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Estimated fair values of financial instruments Fair Value Financial Instruments By Balance Sheet Grouping [Abstract] Fair value financial instruments by balance sheet grouping. Financial assets Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Cash and due from banks, Fair Value Cash and Cash Equivalents, Fair Value Disclosure Interest-bearing deposits in other financial institutions, fair value Interest Bearing Deposits In Banks Fair Value Disclosure Interest bearing deposits in banks fair value disclosure. Federal funds sold and securities purchased under agreements to resell, fair value Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure Investment securities held to maturity Investment securities held to maturity, fair value Investment securities available for sale, at fair value Available-for-sale Securities1 This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale. FHLB and Federal Reserve Bank stocks FHLB and Federal Reserve Bank stocks, fair value Federal Home Loan Bank And Federal Reserve Bank Stocks Fair Value Disclosure Federal Home Loan Bank And Federal Reserve Bank Stocks Fair Value Disclosure. Mortgage Loans Held-for-sale Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage Mortgages Held-for-sale, Fair Value Disclosure Mortgages Held-for-sale, Fair Value Disclosure Commercial Loans Held-for-sale, Fair Value Disclosure Commercial Loans Held-for-sale, Fair Value Disclosure Fair value portion of loans held-for-sale for commercial finance receivables. Loans, net Loans, net, fair value Loans Receivable Net Fair Value Disclosure Loans Receivable Net Fair Value Disclosure. Bank and Corporate Owned Life Insurance Bank owned life insurance, fair value Bank Owned Life Insurance Fair Value Disclosure Bank owned life insurance fair value disclosure. Derivatives (trading and other assets), fair value Financial liabilities Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts Deposits Excluding Time Deposits Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts, fair value Deposits Excluding Time Deposits Fair Value Disclosure Fair Value of noninterest-bearing demand, savings, interest-bearing demand, and money market deposits Brokered CDs and other time deposits Brokered cds and other time deposits Brokered cds and other time deposits Brokered CDs and other time deposits, fair value Brokered cds and other time deposits fair value Brokered cds and other time deposits fair value Short-term funding Short-term funding, fair value Short-term Debt, Fair Value Other long-term funding Long-term funding, fair value Long-term Debt, Fair Value Standby letters of credit Long-term Line of Credit Derivatives (trading and other liabilities) Derivatives (trading and other liabilities), fair value Commitment on standby letters of credit Letters of Credit Outstanding, Amount Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land Land [Member] Land improvements Land Improvements [Member] Buildings and improvements Building and Building Improvements [Member] Computers Computer Equipment [Member] Furniture, fixtures and other equipment Furniture and Fixtures [Member] Leasehold improvements Leasehold Improvements [Member] Minimum Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Net, by Type [Abstract] Property, Plant and Equipment, Net, by Type [Abstract] Estimated Useful Lives Property, Plant and Equipment, Useful Life Cost Property, Plant and Equipment, Gross Accumulated Depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net Book Value Parent Company Only Financial Information Condensed Financial Information of Parent Company Only Disclosure [Text Block] Alternative Securities Alternative Securities [Member] Other Cash and Cash Equivalents [Member] Total Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Goodwill and Intangible Assets Disclosure [Abstract] Summary of changes in balance of mortgage servicing rights asset and mortgage servicing rights valuation allowance Summary Of Changes In Balance Of Mortgage Servicing Rights Asset And Mortgage Servicing Rights Valuation Allowance [Abstract] Summary of changes in balance of mortgage servicing rights asset and mortgage servicing rights valuation allowance. Mortgage servicing rights: Servicing Asset at Fair Value, Amount [Roll Forward] Mortgage servicing rights at beginning of year Servicing Asset at Amortized Cost Additions from acquisition MSR Addition from Business Combination MSR Addition from Business Combination Additions Servicing Asset at Amortized Cost, Additions Amortization Servicing Asset at Amortized Cost, Amortization Mortgage servicing rights at end of year Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward] Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward] Valuation allowance at beginning of year Valuation Allowance for Impairment of Recognized Servicing Assets, Balance (Additions) recoveries, net Valuation Allowance for Impairment of Recognized Servicing Assets, Additions (Deductions) for Expenses (Recoveries) Valuation allowance at end of year Mortgage servicing rights, net Servicing Asset At Amortized Value Net Net amortized carrying amount (balance) as of the balance sheet date of an asset representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs and allowances related to servicing arrangements. Fair value of mortgage servicing rights Servicing Asset at Amortized Cost, Fair Value Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) Portfolio Of Residential Mortgage Loans Serviced For Others Portfolio of residential mortgage loans serviced for others ("servicing portfolio"). Mortgage servicing rights, net to servicing portfolio Mortgage Servicing Rights Net To Servicing Portfolio Mortgage servicing rights, net to servicing portfolio. Mortgage servicing rights expense (a) Mortgage Servicing Rights Expense Includes the amortization of mortgage servicing rights and additions/recoveries to the valuation allowance of mortgage servicing rights, and is a component of mortgage banking, net in the consolidated statements of income. Preferred shares, par value Preferred Stock, Par or Stated Value Per Share Common shares, par value Common Stock, Par or Stated Value Per Share Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Associated Banc-Corp Associated Bank, N.A. Subsidiaries [Member] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Regulatory Capital [Abstract] Regulatory Capital [Abstract] Total Capital Actual Amount Capital Total Capital Actual Ratio Capital to Risk Weighted Assets Total Capital for Capital Adequacy Purposes Amount Capital Required for Capital Adequacy Total Capital for Adequacy Purposes Ratio Capital Required for Capital Adequacy to Risk Weighted Assets Total Capital to be Well Capitalized Amount Capital Required to be Well Capitalized Total Capital to be Well Capitalized Ratio Capital Required to be Well Capitalized to Risk Weighted Assets Tier 1 Capital Actual Amount Tier One Risk Based Capital Tier 1 Capital Actual Ratio Tier One Risk Based Capital to Risk Weighted Assets Tier 1 Capital for Adequacy Purposes Amount Tier One Risk Based Capital Required for Capital Adequacy Tier 1 Capital for Adequacy Purposes Ratio Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Tier 1 Capital To Be Well Capitalized Amount Tier One Risk Based Capital Required to be Well Capitalized Tier 1 Capital To Be Well Capitalized Ratio Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Common Equity Tier One Capital Common Equity Tier One Capital Common Equity Tier One Capital to Risk Weighted Assets Common Equity Tier One Capital to Risk Weighted Assets Common Equity Tier One Capital to Risk Weighted Assets Common Equity Tier One Capital Required for Capital Adequacy Common Equity Tier One Capital Required for Capital Adequacy Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets Tier 1 Equity Capital to be Well Capitalized Amount Common Equity Tier One Capital Required to be Well-Capitalized Tier 1 Equity Capital to be Well Capitalized Ratio Common Equity Tier One Capital Required to be Well Capitalized to Risk Weighted Assets Common Equity Tier One Capital Required to be Well Capitalized to Risk Weighted Assets Tier 1 Leverage Capital Actual Amount Tier One Leverage Capital Tier 1 Leverage Capital Actual Ratio Tier One Leverage Capital to Average Assets Tier 1 Leverage Capital for Adequacy Purposes Amount Tier One Leverage Capital Required for Capital Adequacy Tier 1 Leverage Capital for Adequacy Purposes Ratio Tier One Leverage Capital Required for Capital Adequacy to Average Assets Tier 1 Leverage Capital To Be Well Capitalized Amount Tier One Leverage Capital Required to be Well Capitalized Tier 1 Leverage Capital To Be Well Capitalized Ratio Tier One Leverage Capital Required to be Well Capitalized to Average Assets Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table] Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table] Servicing Contracts [Member] Servicing Contracts [Member] Impaired Finance Receivable [Member] Impaired Finance Receivable [Member] Impaired Finance Receivable [Member] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Discounted Cash Flow [Member] Discounted Cash Flow [Member] Discounted Cash Flow [Member] Appraisals/Discounted Cash Flow [Member] Appraisals/Discounted Cash Flow [Member] Appraisals/Discounted Cash Flow [Member] Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items] Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items] Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Prepayment Speed Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Prepayment Speed Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Weighted average expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Weighted average expected life Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Weighted average per share fair value of options Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Per Share Fair Value Of Stock Options Per share fair value of stock options. Change in assumed health care cost Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract] Effect on total of service and interest cost Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components Effect on total of service and interest cost Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components Effect on postretirement benefit obligation (increase) Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation Effect on postretirement benefit obligation (decrease) Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation Revenue from Contract with Customer [Text Block] Revenue from Contract with Customer [Text Block] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Calculations for basic and diluted earnings per common share Earnings Per Share, Basic and Diluted [Abstract] Preferred stock dividends Common shareholder dividends Dividends, Common Stock Unvested share-based payment awards Unvested Share based Payment Awards Unvested Share based Payment Awards. Undistributed earnings Undistributed Earnings, Basic Undistributed earnings allocated to common shareholders Undistributed Earnings Allocated To Common Shareholders Undistributed earnings allocated to common shareholders Undistributed earnings allocated to unvested share-based payment awards Undistributed Earnings Allocated To Unvested Share Based Payment Awards Undistributed Earnings Allocated To Unvested Share-Based Payment Awards Undistributed earnings UndistributedEarningsAllocations UndistributedEarningsAllocations Basic Earnings Per Share, Basic [Abstract] Distributed earnings to common shareholders Distributed Earnings To Common Shareholders Basic Distributed earnings to common shareholders basic. Undistributed earnings allocated to common shareholders Undistributed Earnings Basic Undistributed Earnings Basic. Total common shareholders earnings, basic Common Shareholders Earnings Basic Common Shareholders Earnings Basic. Diluted Earnings Per Share, Diluted [Abstract] Distributed earnings to common shareholders Distributed Earnings To Common Shareholders Diluted Distributed earnings to common shareholders diluted. Undistributed earnings allocated to common shareholders Undistributed Earnings, Diluted Total common shareholders earnings, diluted Common Shareholders Earnings Diluted Common Shareholders Earnings Diluted. Weighted average common shares outstanding Effect of dilutive common stock awards Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Effect of dilutive common stock warrants Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Diluted weighted average common shares outstanding Basic earnings per common share Diluted earnings per common share Summary of Company's Stock Option Activities Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Stock Options Shares Outstanding, Beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Shares used in acquisition Shares used in acquisition Shares used in acquisition Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Forfeited or expired (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Stock Options Shares Outstanding, Ending balance (in shares) Options exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Stock Options Outstanding, Weighted Average Exercise Price, Beginning balance (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted, Weighted Average Exercise Price (in usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Ex Share Price at Acquisition Ex Share Price at Acquisition Ex Share Price at Acquisition Exercised, Weighted Average Exercise Price (in usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Forfeited or expired, Weighted Average Exercise Price (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Stock Options Outstanding, Weighted Average Exercise Price, Ending balance (in usd per share) Options Exercisable, Weighted Average Exercise Price (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Stock Options Outstanding, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options exercisable, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Stock Options Outstanding, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options exercisable, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Acquisition Business Combination Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Change in Benefit Obligation Schedule of Defined Benefit Plans Disclosures [Table Text Block] AOCI Components Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block] Changes in OCI Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Net period benefit cost for the pension plans Schedule of Net Benefit Costs [Table Text Block] Net period benefit cost for postretirement plan Net period benefit cost for postretirement plan [Table Text Block] [Table Text Block] for Net period benefit cost for postretirement plan [Table] Weighted Average Benefit Assumptions Schedule of Assumptions Used [Table Text Block] Plan Asset Allocation Percentages Schedule of Allocation of Plan Assets [Table Text Block] Pension Plan Investments Schedule Of Pension Plan Investments [Table Text Block] Schedule of Fair Value of Pension Plan Assets Schedule of Changes in Fair Value of Plan Assets Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] One Percentage Point Change in Assumed Health Care Cost Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] BKMU Goodwill Acquired Adjustments [Member] BKMU Goodwill Acquired Adjustments [Member] BKMU Goodwill Acquired Adjustments [Member] BKMU Assets Acquired Liabilities Assumed IncreaseDecrease [Member] BKMU Assets Acquired Liabilities Assumed IncreaseDecrease [Member] BKMU Assets Acquired Liabilities Assumed IncreaseDecrease [Member] Anderson Insurance Investment Agency [Domain] Anderson Insurance Investment Agency [Domain] Anderson Insurance Investment Agency [Domain] Diversified Insurance [Member] Diversified Insurance [Member] Diversified Insurance [Member] Huntington National Bank [Domain] Huntington National Bank [Domain] Huntington National Bank [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Consideration shares transferred Business Combination, Consideration Shares Transferred Shares transferred at acquisition-date in consideration of business combination. Stock Issued During Period, Shares, Acquisitions Goodwill acquired during period Goodwill, Acquired During Period Premises and equipment, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Business Combination, Acquired Receivables, IncreaseDecrease Business Combination, Acquired Receivables, IncreaseDecrease Business Combination, Acquired Receivables, Increase Decrease Business Combination, Consideration Transferred Business Combination, Consideration Transferred Additions to finite-lived intangible assets Finite-lived Intangible Assets Acquired Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Estimate Acquired Deposits Estimate Acquired Deposits Estimate Acquired Deposits Estimate Acquired Loans Estimate Acquired Loans Estimate Acquired Loans Estimate Acquired Net Branches Estimate Acquired Net Branches Estimate Acquired Net Branches Hedge impact on Financial Position [Abstract] Hedge impact on Financial Position [Abstract] Balance Sheet Recording of Fair Value Hedge [Table] Balance Sheet Recording of Fair Value Hedge [Table] Balance Sheet Recording of Fair Value Hedge [Table] Valuation [Axis] Valuation [Axis] Valuation [Axis] Valuation [Domain] Valuation [Domain] [Domain] for Valuation [Axis] adjustment [Member] adjustment [Member] adjustment [Member] Carrying Value [Member] Carrying Value [Member] Carrying Value [Member] Balance Sheet Recording of Fair Value Hedge [Line Items] Balance Sheet Recording of Fair Value Hedge [Line Items] [Line Items] for Balance Sheet Recording of Fair Value Hedge [Table] Derivative Asset, Amortized Cost Basis Derivative Asset, Amortized Cost Basis Derivative Asset, Amortized Cost Basis Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Time Deposits, $100,000 or More Time Deposits, $100,000 or More Time Deposits, $250,000 Or More Time Deposits, $250,000 Or More Time Deposits, $250,000 Or More Loans and Leases Receivable, Related Parties [Roll Forward] Balance at beginning of year Loans and Leases Receivable, Related Parties New loans Loans and Leases Receivable, Related Parties, Additions Repayments Loans and Leases Receivable, Related Parties, Proceeds Changes due to status of executive officers and directors Change Due To Status of Officers And Directors Changes due to status of executive officers and directors Balance at end of year Fair Value Of Plan Assets As A Percentage Of Net Benefit Obligation fairvalueofplanassetsasapercentageofnetbenefitobligation Change in Fair Value of Plan Assets Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Fair value of plan assets at beginning of year Fair value of Bank Mutual plan assets at February 1, 2018 Defined Benefit Plan, Plan Assets, Business Combination Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Gross benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Bank Mutual plan assets transferred at December 31, 2018 Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan Fair value of plan assets at end of year (a) Change in Benefit Obligation Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Net benefit obligation at beginning of year Defined Benefit Plan, Benefit Obligation Net Bank Mutual benefit obligation at February 1, 2018 Defined Benefit Plan, Benefit Obligation, Business Combination Actuarial (gain) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Gross benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Lump sums paid Lump Sum Benefits Paid Lump Sum Benefits Paid Bank Mutual benefit obligations transferred at December 31, 2018 Defined Benefit Plan Transferred to from Plan, Obligation Defined Benefit Plan Transferred to from Plan, Obligation Net benefit obligation at end of year (a) Funded (unfunded) status Defined Benefit Plan, Funded (Unfunded) Status of Plan Noncurrent assets Assets for Plan Benefits, Defined Benefit Plan Current liabilities Liability, Defined Benefit Plan, Current Noncurrent liabilities Liability, Defined Benefit Plan, Noncurrent Asset (Liability) Recognized in the Consolidated Balance Sheets Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State and Local Jurisdiction State and Local Jurisdiction [Member] Internal Revenue Service (IRS) Internal Revenue Service (IRS) [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards Operating Loss Carryforwards Operating tax loss carryforwards from acquisitions Operating Loss Carryforwards By Tax Authority From Acquisitions Operating tax loss carryforwards from acquisitions Tax Credit Carryforward, Amount Tax Credit Carryforward, Amount Deferred Other Tax Expense (Benefit) Deferred Other Tax Expense (Benefit) Other Tax Expense (Benefit) Other Tax Expense (Benefit) Bad debt from acquired savings banks Bad Debt Reserve Of Qualified Thrift Lender Allowance for bad debt acquired from thrifts deducted from taxable income Deferred tax on bad debt from acquired savings banks No deferred tax liability for aquired allowance for bad debt from savings banks Allowance for bad debt acquired from thrifts tax liability if not deductible from taxable income Unrecognized tax benefit impact on effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Interest and penalty expense (benefit) Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Accrued interest and penalties Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Parent Company Balance Sheet Condensed Balance Sheet of Parent Company Only [Table Text Block] Condensed Balance Sheet of Parent Company Only Parent Company Income Statement Condensed Income Statement of Parent Company Only [Table Text Block] Condensed Income Statement of Parent Company Only Parent Company Statement of Cash Flows Condensed Statement of Cash Flows of Parent Company Only [Table Text Block] Condensed Statement of Cash Flows of Parent Company Only Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Lease Breakage Cost [Member] Lease Breakage Cost [Member] Lease Breakage Cost [Member] Depreciation and amortization Depreciation Rental expense under leases Operating Leases, Rent Expense, Net Variable Lease, Cost Variable Lease, Cost Summary of Restricted Stock Awards Activity (Excluding Salary Shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Outstanding Shares, Beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Outstanding Shares, Ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Outstanding, Weighted Average Grant Date Fair Value, Beginning balance (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted, Weighted Average Grant Date Fair Value (in usd 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, Weighted Average Grant Date Fair Value (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited, Weighted Average Grant Date Fair Value (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Outstanding Weighted Average Grant Date Fair Value, Ending balance (in usd per share) Assets and liabilities measured on recurring basis at fair value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Assets and liabilities measured at fair value using significant unobservable inputs (level 3) Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Assets and liabilities measured on nonrecurring basis at fair value Fair Value Measurements, Nonrecurring [Table Text Block] Schedule of assumptions for fair value as of balance sheet date of assets or liabilities that relate to transferor's continuing involvement Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table Text Block] Estimated fair values of financial instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Postretirement Plan Health Care Trend Rate [Table] Postretirement Plan Health Care Trend Rate [Table] Maximum [Member] Health Care Trend Rate by Age [Axis] Health Care Trend Rate by Age [Axis] Health Care Trend Rate [Domain] Health Care Trend Rate [Domain] Pre-65 Health Care Trend Rate [Member] Pre-65 Health Care Trend Rate [Member] Post-65 Health Care Trend [Member] Post-65 Health Care Trend [Member] Asset Allocation Porfolio Segments [Axis] Asset Allocation Porfolio Segments [Axis] Asset Allocation Portfolio Segments [Domain] Asset Allocation Portfolio Segments [Domain] Equity Securities Cash and Cash Equivalents Retirements Plans [Line Items] Retirements Plans [Line Items] Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year Expected long-term rate of return on plan assets Actual return on plan assets percentage Defined Benefit Plan Actual Return on Plan Assets Percentage Defined benefit plan actual percentage return on plan assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Health care trend rate assumption Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Minimum Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Minimum Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Maximum Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Maximum Defined Benefit Plan, Health Care Cost Trend, Reduction in Trend Rate Maximum Ultimate future rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Defined Benefit Plan Health Care Cost Rate Change Defined Benefit Plan Health Care Cost Rate Change Defined Benefit Plan Health Care Cost Rate Change - Actual Value From Previous Time Period Total expense related to 401(k) Defined Contribution Plan, Cost BKMU Assets Acquired Liabilities Assumed Adjustments [Member] BKMU Assets Acquired Liabilities Assumed Adjustments [Member] BKMU Assets Acquired Liabilities Assumed Adjustments [Member] Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Investment securities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities Federal Home Loan Bank stock, at cost Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, FHLB Stock Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, FHLB Stock Loans Business Combination, Acquired Receivable, Fair Value Bank owned life insurance Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Bank Owned Life Insurance Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Bank Owned Life Insurance Goodwill Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Other real estate owned (included in other assets on the face of the Consolidated Balance Sheet) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, OREO Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, OREO Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Income and Other Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Income and Other Assets Total assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Including Goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Including Goodwill Deposits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits Other borrowings Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Borrowings Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Borrowings Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Liabilities and Other Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Liabilities and Other Liabilities Total liabilities Total consideration paid Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Schedule Of Financing Receivable Restructuring [Table] Schedule Of Financing Receivable Restructuring [Table] Financing Receivable Restructurings [Axis] Financing Receivable Restructurings [Axis] Financing Receivable Restructurings [Domain] Financing Receivable Restructurings [Domain] Financing Receivable Restructurings [Domain] Other consumer Performing Restructured Loans Performing Restructured Loans Restructured loans that are accruing Nonaccrual Restructured Loans Nonaccrual Restructured Loans Restructured loans that are on nonaccrual Segment Reporting Segment Reporting Disclosure [Text Block] Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Detail Texuals) [Table] Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Detail Texuals) [Table] Investment Secondary Categorization [Axis] Investment Secondary Categorization [Axis] Investments by Secondary Categorization [Domain] Investments by Secondary Categorization [Domain] UnconsolidatedProjectsLowIncomeHousing [Member] UnconsolidatedProjectsLowIncomeHousing [Member] UnconsolidatedProjectsLowIncomeHousing [Member] Low-income housing, new market tax credits projects and historic tax credit projects. PrincipalInvestmentCommitment [Member] PrincipalInvestmentCommitment [Member] PrincipalInvestmentCommitment [Member] Provided to capital based financing to private and public companies Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items] Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items] Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities. Unfunded commitments Carrying value of investments Other Investments Expense Related to Qualified Affordable Housing Projects Expense Related to Qualified Affordable Housing Projects Expense Related to Qualified Affordable Housing Projects Remaining Investment in Qualified Affordable Housing Projects Remaining Investment in Qualified Affordable Housing Projects Remaining Investment in Qualified Affordable Housing Projects Variable Interest Entity Reporting Entity Involvement Unfunded Obligation Amount Variable Interest Entity Reporting Entity Involvement Unfunded Obligation Amount Variable Interest Entity Reporting Entity Involvement Unfunded Obligation Amount Loans repurchased under make whole requests Loans Repurchased Under Make Whole Requests Loans repurchased under make whole requests Loans sold to outside investors original amount Loans Sold To Outside Investors Original Amount Loans sold to outside investors original amount Loans sold to outside investors remaining outstanding amount Loans Sold To Outside Investors Remaining Outstanding Amount Loans sold to outside investors remaining outstanding amount Residential mortgage loans sold with recourse risk Residential Mortgage Loans Sold With Recourse Risk Residential mortgage loans sold with recourse risk. Residential mortgage loans sold with credit recourse risk Residential Mortgage Loans Sold With Credit Recourse Risk Residential mortgage loans sold with credit recourse risk. Mortgage Servicing Rights Mortgage Service Rights [Member] Mortgage service rights. Estimated future amortization expense Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Year ending December 31, 2019 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Year ending December 31, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two Year ending December 31, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three Year ending December 31, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four Year ending December 31, 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Beyond 2023 Finite-Lived Intangible Assets, Amortization Expense, after Year Five Net book value Finite-Lived Intangible Assets, Net Common Stock, per share Common Stock, Dividends, Per Share, Cash Paid Goodwill, Impairment Loss Goodwill, Impairment Loss FFELP asset backed securities Asset-backed Securities, Securitized Loans and Receivables [Member] Available for Sale Available-for-sale Securities, Debt Maturities [Abstract] Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten 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, Amortized Cost Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten 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 Investment securities available for sale, amortized cost Ratio of Fair Value to Amortized Cost Ratio of Fair Value to Amortized Cost, AFS Ratio of Fair Value to Amortized Cost, AFS Held to Maturity Debt Securities, Held-to-maturity, Maturity [Abstract] Amortized Cost Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Due in one year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due after five years through ten years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Amortized Cost Total debt securities Held-to-maturity Debt Securities, Amortized Cost Basis Held-to-maturity Debt Securities, Amortized Cost Basis Amortized Cost Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due in one year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due after five years through ten years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Total debt securities Held-to-maturity Securities, Debt Securities Held-to-maturity Securities, Debt Securities Total debt securities Ratio of Fair Value to Amortized Cost Ratio of Fair Value to Amortized Cost, HTM Ratio of Fair Value to Amortized Cost, HTM Fair Value, Measurements, Nonrecurring Fair Value, Measurements, Nonrecurring [Member] Assets and Liabilities Measured at Fair Value on a Non-recurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract] Commercial loans held for sale Mortgage loans held for sale Impaired loans Loans Receivable, Fair Value Disclosure Provision for Credit Losses, Impaired Loans Provision for Credit Losses, Impaired Loans Provision for Credit Losses, Impaired Loans Other real estate owned (c) Other Real Estate Owned Fair Value Disclosure Other real estate owned fair value disclosure. Foreclosure / OREO expense, net SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Write-down or Reserve, Amount Mortgage servicing rights Mortgage Servicing Rights (MSR) Impairment (Recovery) Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Pension Plan Investments Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract] Money market account Defined Benefit Plan Fair Value of Plan Assets Money Market Accounts Common /collective trust funds Defined Benefit Plan Fair Value of Plan Assets Mutual Funds Mutual funds Defined Benefit Plan Fair Value of Plan Assets Common/Collective Trust Funds Group annuity contracts Total Retirement Account Plan Investments Summary of core deposit intangibles and other intangibles Schedule of Finite-Lived Intangible Assets [Table Text Block] Summary of changes in balance of mortgage servicing rights asset and mortgage servicing rights valuation allowance Summary Of Changes In Balance Of Mortgage Servicing Rights Asset And Mortgage Servicing Rights Valuation Allowance [Table Text Block] Summary of changes in balance of mortgage servicing rights asset and mortgage servicing rights valuation allowance. Summary of estimated future amortization expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Statement of Comprehensive Income [Abstract] Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax [Abstract] Investment securities available for sale Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax [Abstract] Net unrealized gains (losses) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Net unrealized gain (loss) on available for sale securities transferred to held to maturity securities Other Comprehensive Income (Loss), Transfers from Available-for-Sale Securities to Held-to-maturity, before Tax Other Comprehensive Income (Loss), Transfers from Available-for-Sale Securities to Held-to-maturity, before Tax Amortization of net unrealized gain (loss) on available for sale securities transferred to held to maturity securities Amortization of Net Unrealized Gain on Available-for-Sale Securities Transfered to Held-to-maturity Securities Amortization of Net Unrealized Gain on Available-for-Sale Securities Transfered to Held-to-maturity Securities Reclassification adjustment for net losses (gains) realized in net income (a) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Reclassification from OCI due to change in accounting principle Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax Reclassification of certain tax effects from OCI Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI Reclass Tax Effect, before Tax, Total Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI Reclass Tax Effect, before Tax, Total Income tax (expense) benefit Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax Other comprehensive income (loss) on investment securities available for sale Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Defined benefit pension and postretirement obligations Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract] Amortization of prior service cost Net actuarial (loss) gain Amortization of actuarial loss (gain) Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax Reclassification of certain tax effects from OCI Other Comprehensive Income Loss Reclassification Adjustment From AOCI Defined Benefits Tax Effect BeforeTax Other Comprehensive Income Loss Reclassification Adjustment From AOCI Defined Benefits Tax Effect BeforeTax Income tax (expense) benefit Total other comprehensive income (loss) Summary of lending-related and other commitments Lending Related And Other Commitments [Table Text Block] Lending related and other commitments. Summary of changes in the residential mortgage repurchase reserve Schedule of Representation and Warranty Reserve [Table Text Block] Schedule of Representation and Warranty Reserve [Table Text Block] Adjustments to Core Deposits [Member] Adjustments to Core Deposits [Member] Adjustments to Core Deposits [Member] Summary of core deposit intangibles and other intangibles Finite-Lived Intangible Assets, Net [Abstract] Gross carrying amount Finite-Lived Intangible Assets, Gross Reductions due to sale Finite-Lived Intangible Assets, Period Increase (Decrease) Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Additions during the period Balance Sheet Offsetting of Derivative Assets and Liabilities Balance Sheet Offsetting of Derivative Assets and Liabilities [Table Text Block] Financial assets and liabilities offset on the Balance Sheet or subject to master netting agreements. Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Investment Securities Available for Sale Securities (Assets) [Member] Derivative Financial Instruments Derivatives [Member] Derivatives. Available-for-sale Securities [Member] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Mortgage derivative gain (loss) Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Net Mortgage Derivative Gain (Loss) Included In Earnings Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Net Mortgage Derivative Gain (Loss) Included In Earnings. Fair Value, Assets, Level 3 to Level 2 Transfers, Amount Fair Value, Assets, Level 3 to Level 2 Transfers, Amount Fair Value, Assets, Level 3 to Level 2 Transfers, Amount Ending Balance Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Beginning Balance Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Fair Value, Assets, Level 3 to Level 2 Transfers, Amount Ending Balance Securities Sold [Member] Securities Sold [Member] Securities Sold [Member] Reinvestment [Member] Reinvestment [Member] Reinvestment [Member] Collateral [Axis] Collateral [Axis] Collateral [Domain] Collateral [Domain] Investment Securities Class [Domain] Investment Securities Class [Domain] Investment Securities Taxable Equivalent Yield Taxable Equivalent Yield Taxable Equivalent Yield is the return that is required on a taxable investment to make it equal to the return on a tax-exempt investment. Debt Securities, Available-for-sale, Sold at Par Value Debt Securities, Available-for-sale, Sold at Par Value Securities Received as Collateral Securities Received as Collateral Investment Securities (Textuals) [Abstract] Investment Securities Textuals [Abstract] Investment securities. Proceeds from Sale of Available-for-sale Securities Debt Securities, Held-to-maturity, Sold, Amount Debt Securities, Held-to-maturity, Sold, Amount Debt Securities, Held-to-maturity, Sold, Realized Gain (Loss) Debt Securities, Held-to-maturity, Sold, Realized Gain (Loss) Proceeds from Sale of Securities Proceeds from Sale of Securities The cash inflow associated with the sale of securities that had been designated as either held-to-maturity or available-for-sale. Excludes proceeds from maturities, prepayments and calls by the issuer. Marketable Securities, Gain (Loss) Federal Home Loan Bank Stock Federal Home Loan Bank Stock Federal Reserve Bank Stock Federal Reserve Bank Stock Deferred Tax Assets, Valuation Allowance [Roll Forward] Deferred Tax Assets, Valuation Allowance [Roll Forward] Deferred Tax Assets, Valuation Allowance [Roll Forward] Valuation allowance for deferred tax assets, beginning of year (Increase) decrease in current year Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation allowance for deferred tax assets, end of year Debt Disclosure [Abstract] Long-term Debt, Fiscal Year Maturity [Abstract] Long-term Debt, Fiscal Year Maturity [Abstract] 2019 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2020 Long-term Debt, Maturities, Repayments of Principal in Year Two 2021 Long-term Debt, Maturities, Repayments of Principal in Year Three 2022 Long-term Debt, Maturities, Repayments of Principal in Year Four 2023 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Loan composition Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Loans to Related Parties Loans And Leases Receivable Related Parties [Table Text Block] Table showing loans loans receivable from related parties and the activity during the period. Commercial and consumer loans by credit quality indicator Financing Receivable Credit Quality Indicators [Table Text Block] Summarized details of Loans Past Due Financing Receivables [Table Text Block] Summarized details of impaired Loans Impaired Financing Receivables [Table Text Block] Nonaccrual and performing restructured loans Troubled Debt Restructurings Performing and Nonaccrual [Table Text Block] Troubled Debt Restructurings Performing and Nonaccrual [Table Text Block] Summary of restructured loans Troubled Debt Restructurings on Financing Receivables [Table Text Block] Troubled debt restructurings subsequent redefault Troubled Debt Restructurings Subsequent Default [Table Text Block] Table showing troubled debt restructurings that subsequently redefaulted during the period Changes in the allowance for loan losses by portfolio segment Allowance for Credit Losses on Financing Receivables [Table Text Block] Changes in the allowance for loan losses by oil and gas segment us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlockOilandGas [Table Text Block] us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock [Table Text Block] Changes in the allowance for unfunded commitments Schedule Of Unfunded Commitments [Table Text Block] Schedule of allowance for loans and lease losses table text block. Changes In Accretable Yield For Purchased Credit Impaired asb_ScheduleOfChangesInAccretableYieldForPurchasedCreditImpairedLoansTableTextBlock [Table Text Block] asb_ScheduleOfChangesInAccretableYieldForPurchasedCreditImpairedLoansTableTextBlock [Table Text Block] (Increase) decrease in equity in undistributed net income (loss) of subsidiaries Increase decrease in equity in undistributed net income loss of subsidiaries (Increase) decrease in equity in undistributed net income (loss) of subsidiaries Net increase in notes receivable from subsidiaries Increase (Decrease) in Notes Receivable, Related Parties Purchase of other assets, net of disposals Proceeds from Sale of Productive Assets Net increase (decrease) in short-term funding Repayment of long-term funding Proceeds from issuance of preferred stock Redemption of preferred stock Common stock warrants exercised Issuance of Treasury Stock for Acquisition Cash dividends on common stock Cash dividends on preferred stock Net cash used in financing activities Net increase (decrease) in cash, cash equivalents, and restricted cash Cash and Cash Equivalents, Period Increase (Decrease) Cash, cash equivalents, and restricted cash at beginning of period Cash and Cash Equivalents, at Carrying Value Cash, cash equivalents, and restricted cash at end of period Commercial and industrial Real estate construction Real Estate Construction Port Folio Segment [Member] Real estate construction portfolio segment. Other consumer Installment and Credit Cards Portfolio Segment [Member] Installment portfolio segment. Changes in the allowance for loan losses by portfolio segment Provision for loan losses Allowance for loan losses: Individually evaluated for impairment Collectively evaluated for impairment Acquired and accounted for under ASC 310-30(a) Allowance Attributable to Financing Receivable Acquired and Accounted under Modification of Impaired Loans This element represents the allowance attributable to financing receivables that were acquired and accounted for under ASC 310-30. Loans: Individually evaluated for impairment Collectively evaluated for impairment Acquired and accounted for under ASC 310-30(a) Financing Receivable Acquired and Accounted under Modification of Impaired Loans This element represents the financing receivables that were acquired and accounted for under ASC 310-30. Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Investments Securities Available For Sale Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Defined Benefit Pension and Postretirement Obligations Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Roll Forward] Accumulated Other Comprehensive Income (Loss) [Roll Forward] Accumulated Other Comprehensive Income (Loss) [Roll Forward] Beginning Balance Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, before Tax Investment securities losses (gains), net Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Other Comprehensive Income (Loss), Transfers from Available-for-Sale Securities to Held-to-maturity, before Tax Personnel expense Other Expenses Adjustment for adoption of ASU 2016-01 Adjustment for adoption of ASU 2018-02 Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) Income tax (expense) benefit Other Comprehensive Income (Loss), Tax Ending Balance Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Fair value assumptions of stock options Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Company's Stock Option Activities Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of Restricted Stock Awards Activity (Excluding Salary Shares) Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]