Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Subordinated notes, net of unamortized debt issuance costs Subordinated Debt Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Title of 12(b) Security Title of 12(b) Security Carrying Amount Reported Value Measurement [Member] Weighted average interest rate during the period Debt, Weighted Average Interest Rate Net loans (charged-off) recovered Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery) Adjustment to Compensation, Amount Adjustment to Compensation Amount Pledged Status [Axis] Pledged Status [Axis] Financial Instrument [Axis] Financial Instrument [Axis] Employee Benefit Plans Retirement Benefits [Text Block] Derivative Instrument [Axis] Derivative Instrument [Axis] Measurement Frequency [Axis] Measurement Frequency [Axis] Accrued interest receivable on our loan portfolio Financing Receivable, Accrued Interest, before Allowance for Credit Loss Current income tax expense Current Income Tax Expense (Benefit) Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] Number of outstanding letters of credit Number of outstanding letters of credit Number of Outstanding Letters of Credit Unsettled Issuances of Brokered CDs Unsettled Issuances of Brokered CDs Amount of brokered CDs sold that were not settled by the end of the period. The amount recorded is the selling price including any accrued interest. Doubtful Doubtful [Member] HELD TO MATURITY Debt Securities, Held-to-Maturity, Maturity [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Interest Rate Reduction Contractual Interest Rate Reduction [Member] Financing receivable, modified in prior period, subsequent payment received Financing Receivable, Modified In Prior Period, Subsequent Payment Received Financing Receivable, Modified In Prior Period, Subsequent Payment Received Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year, Writeoff Total unrealized loss Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year AVAILABLE FOR SALE Available-for-Sale Securities, Debt Maturities [Abstract] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Reclassification out of accumulated other comprehensive income Reclassification out of Accumulated Other Comprehensive Income [Member] Exchange [Domain] Exchange [Domain] Other intangible assets, net Intangible Asset, Excluding Goodwill, after Accumulated Amortization Restructured loans and type of modification Financing Receivable, Modified [Table Text Block] Retirement Benefits [Abstract] Retirement Benefits [Abstract] 3-4 Years Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Four Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Four Maximum amount outstanding during the period Borrowings, Maximum Month-end Outstanding Amount Borrowings, Maximum Month-end Outstanding Amount Securities premium amortization (discount accretion), net Accretion (Amortization) of Discounts and Premiums, Investments Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Construction Real Estate Loans Construction Loans [Member] Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Securities AFS, at estimated fair value Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Entity Address, City or Town Entity Address, City or Town FHLB stock, at cost Federal Home Loan Bank Stock Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Receivables [Abstract] Receivables [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Writeoff Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount FHLB borrowings Federal Home Loan Bank Borrowings, Fair Value Disclosure Less than 1 Year Borrowed Funds, Maturities, Repayments of Principal in the Next Rolling Twelve Months Borrowed Funds, Maturities, Repayments of Principal in the Next Rolling Twelve Months Significant Other Observable Inputs (Level 2) Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Commercial Real Estate, Owner Occupied Real Estate Commercial Real Estate, Owner Occupied Real Estate Commercial Real Estate, Owner Occupied Real Estate Other comprehensive income (loss), net of tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Greater than 90 Days Past Due Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Total held-to-maturity investment securities Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration] Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration] Gross proceeds from sales of loans held for sale Proceeds from Sale, Loan, Mortgage, Held-for-Sale Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] 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 securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities and of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity. Net current-period other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Less: Allowance for loan losses Less: Allowance for loan losses Balance at beginning of period Balance at end of period Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Document Period End Date Document Period End Date Maturity of repurchase agreements (less than) Repurchase Agreement Counterparty, Maturity of Agreements Repurchase Agreement Counterparty, Maturity of Agreements Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Debt face amount Debt Instrument, Face Amount Basic earnings per share: Earnings Per Share, Basic [Abstract] Investments, All Other Investments [Abstract] Investments, All Other Investments [Abstract] Debt term Debt Instrument, Term Net realized losses on AFS securities Debt Securities, Available-for-Sale, Realized Loss Interest rate at end of the period Debt Instrument, Interest Rate, Effective Percentage Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Brokerage services Brokerage Commissions Revenue Securities sold under repurchase agreements Securities Sold under Agreements to Repurchase AOCI Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Percent of Total Class Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Due after five years through ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost Earnings Per Share Earnings Per Share [Text Block] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Total liabilities Liabilities Trading Symbol Trading Symbol Securities AFS, at estimated fair value (amortized cost of $1,579,607 and $1,456,986, respectively) Securities AFS, at estimated fair value Total Debt Securities, Available-for-Sale, Excluding Accrued Interest Allowances for Loan Losses [Roll Forward] Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward] Purchases of premises and equipment Payments to Acquire Property, Plant, and Equipment Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Proceeds from FHLB borrowings Proceeds from FHLBank Borrowings, Financing Activities Company Selected Measure Name Company Selected Measure Name Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Fair Value, Cumulative Increase (Decrease) Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Fair Value, Cumulative Increase (Decrease) Purchases Payments to Acquire Debt Securities, Available-for-Sale Change in unrealized holding gain (loss) on AFS securities during the period OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment and Tax Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Deposits Interest Expense, Deposits Diluted earnings per share: Earnings Per Share, Diluted [Abstract] Line of credit, capacity available for issuance of letters of credit Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Equity investments Equity Securities, FV-NI, Cost Credit Facility [Domain] Credit Facility [Domain] Cash dividends paid per common share (in dollars per share) Cash dividends paid on common stock (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Net issuance of common stock under employee stock plans Stock Issued During Period Value Share Based Compensation Including Effects Of Retained Earnings Stock Issued During Period Value Share Based Compensation Including Effects Of Retained Earnings Line of Credit Facility [Table] Line of Credit Facility [Table] Interest income recognized on securities Investment Income [Table Text Block] Investment securities: Investments, Fair Value Disclosure [Abstract] Commitments to extend credit Commitments to Extend Credit [Member] Proceeds from (purchases of) BOLI Payments for (Proceeds from) Life Insurance Policies Total unrealized loss Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss MBS: Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost Award Timing Predetermined Award Timing Predetermined [Flag] Interest income: Interest and Dividend Income, Operating [Abstract] Subordinated notes, remaining maturity, greater than Subordinated Notes, Remaining Maturity Subordinated Notes, Remaining Maturity Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Stock compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Quoted Prices in Active Markets for Identical Assets (Level 1) Level 1 Fair Value, Inputs, Level 1 [Member] Due after ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Effective income tax rate, percent Effective Income Tax Rate Reconciliation, Percent Accelerated amortization of debt issuance costs and discounts Accelerated Amortization Of Debt Issuance Costs And Discounts Accelerated Amortization Of Debt Issuance Costs And Discounts Add: Stock awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Available-for-sale [Abstract] Securities AFS: Debt Securities, Available-for-Sale [Abstract] Off-Balance Sheet, Credit Loss, Liability [Roll Forward] Off-Balance-Sheet, Credit Loss, Liability [Roll Forward] Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Residential Residential MBS Residential Mortgage-Backed Securities [Member] Scenario [Domain] Scenario [Domain] Total available-for-sale investment securities Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Operating lease ROU assets Operating Lease, Right-of-Use Asset AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Securities Investment in Debt and Equity Securities and Other Trading Assets [Text Block] Cash dividends paid Payments of Ordinary Dividends, Common Stock Expiration Date Trading Arrangement Expiration Date Hedging Relationship [Axis] Hedging Relationship [Axis] Gross unrealized gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Deferred Loss on Discontinuation of Fair Value Hedge Deferred (Gain) Loss on Discontinuation of Fair Value Hedge Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Interest bearing Interest-Bearing Deposit Liabilities Deposits Deposits, Fair Value Disclosure INVESTING ACTIVITIES: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Asset Derivative Derivative Asset [Abstract] Interest rate swap derivatives Interest Rate Swap Interest Rate Swap [Member] Borrowing Arrangements Debt Disclosure [Text Block] Scenario [Axis] Scenario [Axis] Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Loans held for sale Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Available for sale, Fair Value Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Loans to individuals Consumer Loan [Member] Total held-to-maturity investment securities Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Cash dividends paid on common stock Dividends, Common Stock, Cash Total shareholders’ equity Beginning balance, net of tax Ending balance, net of tax Equity, Attributable to Parent Federal funds sold Federal Funds Sold Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] ASSETS Assets [Abstract] Number of credit lines maintained by the Company Line of Credit Facility, Number of Credit Lines Maintained by the Company Line of Credit Facility, Number of Credit Lines Maintained by the Company Summary of loans by credit quality indicators and origination year Financing Receivable Credit Quality Indicators [Table Text Block] Fair Value, Nonrecurring Fair Value, Nonrecurring [Member] Professional fees Professional Fees Insider Trading Policies and Procedures [Line Items] Nonperforming Assets Nonperforming Financial Instruments [Member] Deferred tax expense (benefit) Deferred income tax expense (benefit) Deferred Income Tax Expense (Benefit) Commercial Real Estate Loans Commercial Real Estate Portfolio Segment [Member] Realized net (loss) gain on interest rate swap derivatives Interest Income (Expense), Nonoperating Number of antidilutive shares (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Federal Home Loan Bank borrowings interest rates Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Interest Rate at Period End Entity Central Index Key Entity Central Index Key Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Paid-in capital Additional Paid in Capital, Common Stock Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Reversal of interest income on nonaccrual loans Financing Receivable, Nonaccrual, Interest Income Reversal Financing Receivable, Nonaccrual, Interest Income Reversal Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Derivatives designated as hedging instruments Designated as Hedging Instrument [Member] Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Total Borrowed Funds, Maturities, Repayments of Principal Borrowed Funds, Maturities, Repayments of Principal Magnolia Trust Company I Magnolia Trust Company I [Member] Debt obligation for Magnolia Trust Company I. Basis on variable rate Debt Instrument, Basis Spread on Variable Rate Nonaccrual loans, no allowance Financing Receivable, Excluding Accrued Interest, Nonaccrual, No Allowance Gross originations of loans held for sale Payment for Origination and Purchase, Loan, Held-for-Sale Accumulated Other Comprehensive Income (Loss) Total AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Amortized cost of hedged assets Hedged Asset, Fair Value Hedge Due in one year or less Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Statement [Line Items] Statement [Line Items] Total assets Assets Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Amortization Period Extension Extended Maturity [Member] Total interest expense Interest Expense, Operating Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Corporate bonds and other Interest Income, Securities, Corporate Debt, Operating Reclassification adjustment for net (gain) loss on sale of AFS securities, included in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Gross unrealized gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax MBS: Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Fair Value Net occupancy Occupancy, Net PEO PEO [Member] Noninterest bearing Noninterest-Bearing Deposit Liabilities Goodwill Goodwill Retirement Plan Type [Axis] Retirement Plan Type [Axis] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Thereafter Borrowed Funds, Maturities, Repayments of Principal in Rolling after Year Five Borrowed Funds, Maturities, Repayments of Principal in Rolling after Year Five Retained Earnings Retained Earnings [Member] Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] Net actuarial loss Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Award Timing Disclosures [Line Items] Financial assets, financial liabilities, and unrecognized financial instruments at carrying amount and fair value Fair Value, by Balance Sheet Grouping [Table Text Block] Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Corporate bonds and other Corporate Debt Securities [Member] Earnings per common share - diluted (in dollars per share) Earnings per common share - diluted (in dollars per share) Earnings Per Share, Diluted Held-to-maturity Securities, Other Disclosure Items [Abstract] Debt Securities, Held-to-Maturity, Parenthetical Disclosure [Abstract] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] FDIC insurance Federal Deposit Insurance Corporation Premium Expense Net gains (losses) recognized during the period on equity investments Unrealized Gain (Loss) on Investments Amortization of intangibles Intangible Asset, Finite-Lived, Amortization Expense Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Tax (expense) benefit Reclassification from AOCI, Current Period, Tax Investment Investment [Table Text Block] Securities transferred, Unrealized Loss, Net of Tax Securities Transferred, Unrealized Loss, Net Of Tax Securities Transferred, Unrealized Loss, Net Of Tax Other borrowings Federal Funds Purchased and Securities Sold under Agreements to Repurchase Financial assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Reclassification adjustment for amortization related to AFS and HTM debt securities Amortization of unrealized gains and losses Amortization of Unrealized Gains (Losses) on Securities Transferred Between Available-for-Sale And Held to Maturity Debt Securities, Before Tax Amortization of Unrealized Gains (Losses) on Securities Transferred Between Available-for-Sale And Held to Maturity Debt Securities, Before Tax Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Interest payable Increase (Decrease) in Interest Payable, Net HELD TO MATURITY Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss [Abstract] Noncash Adjustment To Pension Liability Noncash Adjustment To Pension Liability Noncash Adjustment to pension liability during the period related to benefit plans, before tax. Due after one year through five years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Loss on redemption of subordinated notes Gain (Loss) on Repurchase of Debt Instrument Asset Pledged As Collateral, Excess Amount Asset Pledged As Collateral, Excess Amount [Member] Asset Pledged As Collateral, Excess Amount Due after one year through five years Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Total nonperforming assets Financing Receivable, Nonperforming And Repossessed Assets Financing Receivable, Nonperforming And Repossessed Assets MBS Interest Income, Securities, Mortgage-Backed Collateral Held [Axis] Collateral Held [Axis] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Financing Receivable, Excluding Accrued Interest, Revolving Financing Receivable, Excluding Accrued Interest, Revolving Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract] Debt Securities, Available-for-Sale, Realized Gain (Loss) [Abstract] Allowance for loan losses activity by portfolio segment Financing Receivable, Allowance for Credit Loss [Table Text Block] Common stock, shares issued (in shares) Common Stock, Shares, Issued Due after ten years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years More than 12 Months, unrealized Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Principal amount repaid Debt Instrument, Repaid, Principal Due after ten years Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Federal Home Loan Bank borrowings, additional funding available Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds Net (gain) loss on OREO Gains (Losses) on Sales of Other Real Estate Noninterest expense: Noninterest Expense [Abstract] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Commercial Real Estate Portfolio Segment, Owner-Occupied Loans Commercial Real Estate Portfolio Segment, Owner-Occupied Loans [Member] Commercial Real Estate Portfolio Segment, Owner-Occupied Loans Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Financing Receivable, Modified, Subsequent Default Financing Receivable, Modified, Subsequent Default Advertising, travel & entertainment Marketing and Advertising Expense Termination Date Trading Arrangement Termination Date Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Fair Value as of Grant Date Award Grant Date Fair Value Collateral Pledged Collateral Pledged [Member] Redemption percentage Debt Instrument, Redemption Price, Percentage Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Less than 12 Months, unrealized loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Financing Receivable, Excluding Accrued Interest, Modified, Accumulated Financing Receivable, Excluding Accrued Interest, Modified, Accumulated Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Other borrowings Interest Expense, Other FHLB borrowings Interest Expense, Federal Home Loan Bank and Federal Reserve Bank Advances, Short-Term 4-5 Years Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Five Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Five Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Total available-for-sale investment securities Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value All Award Types Award Type [Domain] Fair Value Measurement Fair Value Disclosures [Text Block] NYSE Texas NYSE TEXAS, INC. [Member] Significant Unobservable Inputs (Level 3) Level 3 Fair Value, Inputs, Level 3 [Member] Asset Pledged as Collateral Asset Pledged as Collateral [Member] Common stock purchased (in shares) Treasury Stock, Shares, Acquired Derivatives: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax [Abstract] Less: Allowance for Credit Losses Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest Equity investments Equity investments Equity Securities, FV-NI and without Readily Determinable Fair Value Other assets Other Assets ATM expense ATM Expense Expenses associated with ATMs. 30-59 Days Past Due Financial Asset, 30 to 59 Days Past Due [Member] Purchase of common stock Treasury Stock, Value, Acquired, Cost Method Noninterest income: Noninterest Income [Abstract] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation 3.875% Subordinated Notes 3.875% Subordinated Notes [Member] 3.875% Subordinated Notes Reclassifications out of accumulated other comprehensive income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Non-NEOs Non-NEOs [Member] Due after ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost Held to maturity, Fair Value Debt Securities, Held-to-Maturity, Fair Value, Maturity [Abstract] Less: Net gains recognized during the period on equity investments sold during the period Equity Securities, Realized Gain Equity Securities, Realized Gain Schedule of Debt Schedule of Debt [Table Text Block] Collateral-dependent loans Financing Receivable, Collateral Dependent Financing Receivable, Collateral Dependent Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Purchase of common stock Payments for Repurchase of Common Stock Statistical Measurement [Axis] Statistical Measurement [Axis] Derivative Instruments, Gain (Loss) Derivative Instruments, Gain (Loss) [Table Text Block] Award Type Award Type [Axis] Change in net unrealized gain (loss) on effective cash flow hedge interest rate swap derivatives Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Retained earnings Retained Earnings (Accumulated Deficit) Retirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Foreclosed assets Repossessed Assets Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Retirement Plan Pension Plan [Member] Common Stock Common Stock [Member] Schedule of Fair Value, Off-balance Sheet Risks [Table] Fair Value, off-Balance-Sheet Risk [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Sale of HTM portfolio Proceeds from Sale of Held-to-Maturity Securities Derivative Contract [Domain] Derivative Contract [Domain] Financial Asset, Past Due Financial Asset, Past Due [Member] Net gain (loss) on sale of securities AFS Net (gain) loss on sale of AFS securities Realized net gain (loss) on sale of securities Net gain (loss) on sale of securities AFS Debt Securities, Available-for-Sale, Realized Gain (Loss) Total liabilities and shareholders’ equity Liabilities and Equity Unrealized gains (losses) recognized during the reporting period on equity investments held at the reporting date Realized Investment Gains (Losses) Employee Stock Option Share-Based Payment Arrangement, Option [Member] Reclassification adjustments included in net income Reclassified from accumulated other comprehensive income Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Asset Class [Axis] Asset Class [Axis] FHLB stock with other-than-temporary impairment Federal Home Loan Bank Stock With Other-Than-Temporary Impairment Federal Home Loan Bank Stock With Other-Than-Temporary Impairment Tabular List, Table Tabular List [Table Text Block] Amortized cost and estimated fair value of investment and mortgage-backed securities Unrealized Gain (Loss) on Investments [Table Text Block] Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Due after one year through five years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Loans transferred to other repossessed assets and real estate through foreclosure Real Estate Owned, Transfer to Real Estate Owned Preferred stock: (no par value, 8,000,000 shares authorized, none issued or outstanding) Preferred Stock, Value, Issued Adjustment to Compensation: Adjustment to Compensation [Axis] Total reclassifications for the period, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax FHLB stock, at cost Investment in Federal Home Loan Bank Stock, Fair Value Disclosure Average amount outstanding during the period Borrowings, Average Amount Outstanding Borrowings, Average Amount Outstanding Net change in deposits Net Change Interest and Noninterest-Bearing Deposits, Domestic 7.0% Subordinated Notes Due 2035 7.0% Subordinated Notes Due 2035 [Member] 7.0% Subordinated Notes Due 2035 Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity FHLB borrowings Federal Home Loan Bank, Advance, Branch of FHLBank, Amount Hedging Designation [Axis] Hedging Designation [Axis] 60-89 Days Past Due Financial Asset, 60 to 89 Days Past Due [Member] Earnings allocated to participating securities, basic Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Debt Security Category [Axis] Debt Security Category [Axis] Credit Facility [Axis] Credit Facility [Axis] Total asset fair value measurements Assets, Fair Value Disclosure Proceeds from sales of repossessed assets Proceeds from Sale of Foreclosed Assets Retirement Plan Acquired Other Pension Plan [Member] Name Measure Name Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Financial instruments with off-balance-sheet risk, at fair value Fair Value Disclosure, off-Balance-Sheet Risks, Amount, Liability Debt Instrument [Line Items] Debt Instrument [Line Items] Loans Interest and Fee Income, Financing Receivable Paid In Capital Additional Paid-in Capital [Member] Schedule of unused commitments Schedule of Fair Value, off-Balance-Sheet Risks [Table Text Block] Interest receivable Interest Receivable Name Trading Arrangement, Individual Name Total cash and cash equivalents Cash and Cash Equivalent Subordinated notes Interest Expense, Subordinated Notes and Debentures Company Selected Measure Amount Company Selected Measure Amount Weighted Average Pay Rate Derivative, Weighted Average Pay Rate Derivative, Weighted Average Pay Rate Depreciation and net amortization Depreciation, Depletion and Amortization Loan (discount accretion) premium amortization, net Investment Income, Net, Amortization of Discount and Premium Commercial Owner Occupied Commercial Owner Occupied [Member] Commercial Owner Occupied Net issuance of common stock under employee stock plans (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] State and political subdivisions Interest Income, Securities, State and Municipal Non-PEO NEO Non-PEO NEO [Member] Proceeds from sales of premises and equipment Proceeds From Sale Of Property, Plant And Equipment, Net Proceeds From Sale Of Property, Plant And Equipment, Net Total noninterest expense Noninterest Expense Award Timing Method Award Timing Method [Text Block] Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forecast Forecast [Member] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Debt Securities, Available-for-Sale, Accrued Interest Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss Net loss amortization Defined Benefit Plan, Amortization of Gain (Loss) Mortgage-backed securities Debt Securities, Held-to-Maturity, Maturity, without Single Maturity Date, Fair Value Net income Net income Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Restatement Determination Date: Restatement Determination Date [Axis] Schedule of accumulated other comprehensive income (loss) by component Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] 1-2 Years Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Two Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Two Net of tax Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Federal funds purchased Federal Funds Purchased Off-balance-sheet, Allowance for off-balance-sheet credit exposures Off-balance-sheet, Allowance for off-balance-sheet credit exposures [Table Text Block] Off-balance-sheet, Allowance for off-balance-sheet credit exposures [Table Text Block] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] OPERATING ACTIVITIES: Payments for Operating Activities [Abstract] Frost Bank Frost Bank [Member] Frost Bank [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Document Fiscal Year Focus Document Fiscal Year Focus Offsetting derivative liabilities Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Cash collateral received/posted Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Offset Preferred Stock, No Par Value Preferred Stock, No Par Value Total deposits Deposits Common stock:  ($1.25 par value, 80,000,000 shares authorized, 38,124,707 shares issued at June 30, 2026 and 38,110,078 shares issued at December 31, 2025) Common Stock, Value, Issued Cash paid to tax authority related to tax withholding on share-based awards Payment, Tax Withholding, Share-Based Payment Arrangement Schedule of Long-term Debt Instruments Schedule of Long-Term Debt Instruments [Table Text Block] Communications Communication Restatement Determination Date Restatement Determination Date Cash collateral received/posted Cash collateral received from counterparties under master netting agreements Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash, Offset Against Derivative Asset Restoration Plan Other Pension, Postretirement and Supplemental Plans [Member] Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Due after five years through ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value Other Other Noninterest Expense Unsettled trades to purchase securities Unsettled Trades to Purchase Securities Liability Amount of securities purchased that were not settled by the end of the period. The amount recorded is the purchase price including any accrued interest. This asset is collected upon delivery of the securities. Loans and Allowance for Loan Losses Financing Receivables [Text Block] Amendment Flag Amendment Flag Loans: Loans and Leases Receivable, Net Amount [Abstract] Gross unrealized losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps Weighted Average Maturity And Interest Rates On Risk Management Interest Rate Swaps [Table Text Block] [Table Text Block] for Weighted average remaining maturity of the notional amount of risk management interest rate swaps and weighted average interest rates. Standby letters of credit Standby Letters of Credit [Member] Unsettled trades to repurchase common stock Unsettled Trades to Repurchase Common Stock Unsettled Trades to Repurchase Common Stock Weighted Average Receive Rate Derivative, Weighted Average Receive Rate Derivative, Weighted Average Receive Rate FHLB borrowings: Federal Home Loan Bank Advances [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Financing Receivable, Troubled Debt Restructuring, Restructured Financing Receivable, Troubled Debt Restructuring, Restructured Financing Receivable, Troubled Debt Restructuring, Restructured Entity Address, State or Province Entity Address, State or Province Nonaccrual loans Financing Receivable, Excluding Accrued Interest, Nonaccrual PEO Total Compensation Amount PEO Total Compensation Amount Derivative, Notional Amount Derivative, Notional Amount Basic weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Securities AFS and transferred securities: OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax [Abstract] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Interest earning deposits Interest-Bearing Deposits in Banks and Other Financial Institutions Total interest income on securities Interest and Other Income Interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Total noninterest income Noninterest Income Purchases of FHLB stock and equity investments Payments to Acquire Federal Home Loan Bank Stock Available for sale, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Document Information [Line Items] Document Information [Line Items] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Net income available to common stockholders, basic Net Income (Loss) Available to Common Stockholders, Basic Number of third party sources used to validate prices, in some cases Number of Third Party Sources Used to Validate Prices Number of Third Party Sources Used to Validate Prices Issuance of common stock for dividend reinvestment plan Stock Issued During Period, Value, Dividend Reinvestment Plan Line of credit, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Net loans Total loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Treasury stock: (shares at cost, 8,321,665 at June 30, 2026 and 8,387,077 at December 31, 2025) Treasury Stock, Value Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax Total long-term debt Long-Term Debt Issuance of common stock for dividend reinvestment plan (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Net change in: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Less than 12 months, unrealized loss Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Net cash provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] 1-4 Family Residential Real Estate Loans Residential Real Estate [Member] Security Exchange Name Security Exchange Name Amortized Cost Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Federal Reserve Discount Window Federal Reserve Discount Window [Member] Federal Reserve Discount Window [Member] Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Amount Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Amount TIB - The Independent Bankers Bank TIB - The Independent Bankers Bank [Member] TIB - The Independent Bankers Bank [Member] More than 12 Months, fair value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Repurchase Agreements Repurchase Agreements [Member] Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] HTM, at carrying value Debt Security, Mortgage-Backed, Held-to-Maturity, Fair Value Disclosure Held to maturity, Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity [Abstract] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Schedule of Investments [Table] Schedule of Investments [Table] Total fair value Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value Southside Statutory Trust III Southside Statutory Trust III, net of unamortized debt issuance costs [Member] Debt obligations for Southside Statutory Trust III. SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES: Noncash Investing and Financing Items [Abstract] Net change in other borrowings Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net Retirement Plans Amortization of pension plan Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Securities AFS Debt Securities [Member] Asset Class [Domain] Asset Class [Domain] Repayment of FHLB borrowings Payments of FHLBank Borrowings, Financing Activities Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Diluted weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Southside Statutory Trust V Southside Statutory Trust V [Member] Debt obligation for Southside Statutory Trust V. Mortgage Loans in Process of Foreclosure, Amount Mortgage Loans in Process of Foreclosure, Amount General Loan Term General Loan Term General Loan Term Loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Underlying Security Market Price Change Underlying Security Market Price Change, Percent Derivative Financial Instruments and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Gross unrealized losses Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss Credit exposure related to interest rate swaps Fair Value, Concentration of Risk, Derivative Instruments, Assets Gross derivatives Derivative Liability, Subject to Master Netting Arrangement, before Offset Financial Asset, Closed Portfolio, Portfolio Layer Method, Amortized Cost Financial Asset, Closed Portfolio, Portfolio Layer Method, Amortized Cost Provision for (reversal of) off-balance-sheet credit exposures Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) Debt Securities, Held-to-Maturity, Accrued Interest Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss Treasury Stock Treasury Stock, Common [Member] Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Commercial loans Commercial Loan [Member] Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Collateral Held [Domain] Collateral Held [Domain] All Executive Categories All Executive Categories [Member] Commercial Real Estate, Non-Owner Occupied Real Estate Commercial Real Estate, Non-Owner Occupied Real Estate Commercial Real Estate, Non-Owner Occupied Real Estate Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] The components of net periodic benefit cost Schedule of Net Benefit Costs [Table Text Block] Accruing loans past due more than 90 days Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing Software and data processing Information Technology and Data Processing Earnings per share on a basic and diluted basis Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Maturities, calls and principal repayments Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Minimum Minimum [Member] Less than 12 months, fair value Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Redemption of subordinated notes Repayments of Subordinated Debt Equity investments Investments, Fair Value Disclosure Other borrowings Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure Location, Statement of Income, Balance [Axis] Location, Statement of Income, Balance [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Total liability fair value measurements Financial Liabilities Fair Value Disclosure Derivative Derivative [Member] Other liabilities Other Liabilities Net periodic benefit cost (income) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Other Noninterest Income, Other Operating Income Proceeds from redemption of FHLB stock and equity investments Proceeds from Sale of Federal Home Loan Bank Stock Securities HTM: Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract] Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Accumulated Other Comprehensive Income by Component, Changes [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Gross realized gains on AFS securities Debt Securities, Available-for-Sale, Realized Gain Due after five years through ten years Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value Exercise Price Award Exercise Price Schedule of Maturities of Borrowings Schedule of Maturities of Borrowings [Table Text Block] [Table Text Block] for Tabular disclosure of the combined aggregate amount of maturities for all borrowings for each of the five years following the date of the latest balance sheet date presented. Trust preferred subordinated debentures Interest Expense, Junior Subordinated Debentures Securities HTM (estimated fair value of $1,075,537 and $1,103,304, respectively) Net Carrying Amount Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss Fair Value, Recurring Fair Value, Recurring [Member] Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] State and political subdivisions US States and Political Subdivisions Debt Securities [Member] Lender Name [Axis] Lender Name [Axis] Special Mention Special Mention [Member] Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Sales Proceeds from sale of AFS securities Proceeds from Sale of Debt Securities, Available-for-Sale Liability Derivative Derivative Liability [Abstract] Amegy Bank Amegy Bank [Member] Amegy Bank [Member} Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] Collateral-dependent loans Loans, net of allowance for loan losses Loans Receivable, Fair Value Disclosure Adoption Date Trading Arrangement Adoption Date Subordinated notes, net of unamortized debt issuance costs Subordinated Debt Obligations, Fair Value Disclosure Counterparty Name [Domain] Counterparty Name [Domain] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Proceeds from the issuance of common stock for dividend reinvestment plan Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Remaining Maturity Derivative, Average Remaining Maturity Operating lease liabilities Operating Lease, Liability Securities held-to-maturity, fair value Estimated Fair Value Total Debt Securities, Held-to-Maturity, Fair Value Taxable investment securities Interest Income, Securities, Operating, Taxable Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Loans Loans Receivable [Member] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Off-Balance-Sheet Arrangements, Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] All Adjustments to Compensation All Adjustments to Compensation [Member] Net cash provided by (used in) operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Due in one year or less Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling within One Year Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling within One Year Substandard Substandard [Member] Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition Report Deferred tax asset, net Deferred Income Tax Assets, Net Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Nonperforming Assets [Table] Nonperforming Assets [Table] Nonperforming Assets [Table] City Area Code City Area Code Document Information [Table] Document Information [Table] Trust preferred subordinated debentures, net of unamortized debt issuance costs Debt Instrument, Fair Value Disclosure Name Forgone Recovery, Individual Name Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Trust fees Fees And Commissions Fiduciary And Trust Activity Income from services rendered by trust departments or by any consolidated subsidiaries acting in a fiduciary capacity, including fees earned for (1) acting as an agent for fiduciary placement and loans and (2) custody or investment advisory services when such fees are not separately billed to the customer. This item excludes commissions and fees received for the accumulation or disbursement of funds deposited to Individual Retirement or Keogh plan accounts when such are not handled by the reporting entity's trust department. Pass Watch Pass Watch [Member] A category of financing receivables not considered to be special mention, substandard, doubtful, and loss receivables. Total interest and dividend income Interest and Dividend Income, Operating Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, before Tax Other assets Increase (Decrease) in Other Operating Assets New York Stock Exchange NEW YORK STOCK EXCHANGE, INC. [Member] Measurement Basis [Axis] Measurement Basis [Axis] Offsetting derivative assets Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Unrealized Gains (Losses) on Securities Unrealized gains (losses) AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Summary of fair value measurement on recurring and nonrecurring basis segregated by level of valuation inputs within fair value hierarchy utilized to measure fair value Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Due after five years through ten years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years Accumulated Other Comprehensive Income by Component, Changes [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Cash flow hedging Cash Flow Hedging Cash Flow Hedging [Member] Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Nonaccrual Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Nonaccrual Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Adjustments to reconcile net income to net cash provided by operations: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] More than 12 months, unrealized loss Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss FINANCING ACTIVITIES: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Premises and equipment, net Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization FHLB stock and equity investments Other Interest and Dividend Income Interest cost Defined Benefit Plan, Interest Cost Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Investments, Debt Securities [Abstract] Investments, Debt Securities [Abstract] Investments, Debt Securities [Abstract] Financial Instruments [Domain] Financial Instruments [Domain] Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Net derivatives included in the consolidated balance sheets Derivative assets Derivative Asset Underlying Securities Award Underlying Securities Amount Estimated Fair Value Estimate of Fair Value Measurement [Member] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Combination Extended Maturity and Interest Rate Reduction [Member] Modified in period, amount Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Provision for (reversal of) credit losses Provision for Loan, Lease, and Other Losses Balance at beginning of period Balance at end of period Off-Balance-Sheet, Credit Loss, Liability Repossessed assets Other Repossessed Assets Fair value of securities transferred from AFS to HTM Securities Transferred From Available for Sale to Held to Maturity Securities Transferred From Available for Sale to Held to Maturity Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Less than 12 Months, fair value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Amortization of net actuarial loss, included in net periodic benefit cost Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) and Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) and Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Current Fiscal Year End Date Current Fiscal Year End Date Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Provision for (reversal of) loan losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Derivative [Line Items] Derivative [Line Items] AVAILABLE FOR SALE Debt Securities, Available-for-Sale, Unrealized Gain (Loss) [Abstract] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Entity File Number Entity File Number Due in one year or less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Amortized cost, carrying value and fair value of securities presented by contractual maturity Investments Classified by Contractual Maturity Date [Table Text Block] Transferred Securities, Unrealized Loss, Before Tax Transferred Securities, Unrealized Loss, Before Tax Transferred Securities, Unrealized Loss, Before Tax Deposit services Fee And Commissions Depositor Account Includes amounts charged depositors for: (1) maintenance of their accounts (maintenance charges); (2) failure to maintain specified minimum balances on account; (3) exceeding the number of checks or transactions allowed to be processed in a given period; (4) checks drawn on no minimum balance deposit accounts; (5) withdrawals from nontransaction deposit accounts; (6) closing savings accounts before a specified minimum period of time has elapsed; (7) accounts which have remained inactive for extended periods of time or which have become dormant; (8) use of automated teller machines or remote service units; (9) checks drawn against insufficient funds that the bank assesses regardless of whether it decides to pay, return or hold the check; (10) issuing stop payment orders; (11) certifying checks; and (12) accumulating or disbursing funds deposited in IRAs or Keogh Plan accounts when not handled by the bank's trust department. This item does not include penalties assessed on the early withdrawal of time deposits. Reclassification adjustment of net (gain) loss related to derivatives designated as cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Measure: Measure [Axis] Shares purchased (in shares) Treasury Stock, Common, Shares Nonperforming Assets [Line Items] Nonperforming Assets [Line Items] [Line Items] for Nonperforming Assets [Table] Tax-exempt investment securities Interest Income, Securities, Operating, Tax Exempt Equity Components [Axis] Equity Components [Axis] Debt instrument repurchase Debt Instrument, Repurchase Amount Deferred tax assets, valuation allowance Deferred Tax Assets, Valuation Allowance Entity Interactive Data Current Entity Interactive Data Current Unrealized gains and losses on available for sale securities Available-for-sale Securities Available-for-Sale Securities [Member] HELD TO MATURITY Debt Securities, Held-to-Maturity, Transfer, Unrealized Gain (Loss) [Abstract] Entity Small Business Entity Small Business Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net interest income Interest Income (Expense), Operating MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Document Type Document Type 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] Loss on redemption of subordinated notes Gain (Loss) on Extinguishment of Debt Less: Allowance for Credit Losses Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Net proceeds from sales of OREO Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans Schedule of Subordinated Borrowing Schedule of Subordinated Borrowing [Table Text Block] Debt [Table] Debt [Table] Debt [Table] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Pledged Status [Domain] Pledged Status [Domain] Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Off-balance-sheet arrangements, commitments and contingencies (Note 12) Commitments and Contingencies Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Other borrowings: Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] Reclassifications out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Executive Category: Executive Category [Axis] Income tax (expense) benefit related to items of other comprehensive income (loss) Income tax (expense) benefit Other Comprehensive Income (Loss), Tax Counterparty Name [Axis] Counterparty Name [Axis] LIABILITIES AND SHAREHOLDERS’ EQUITY LIABILITIES AND EQUITY Liabilities and Equity [Abstract] MBS: Mortgage Backed And Related Securities [Abstract] Mortgage Backed And Related Securities [Abstract] U.S. Treasury Interest Income, Securities, US Treasury Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Financing Receivable, Modified, Subsequent Default, Number Of Contracts Financing Receivable, Modified, Subsequent Default, Number Of Contracts Financing Receivable, Modified, Subsequent Default, Number Of Contracts Gain (loss) on sale of loans Gain (Loss) on Sales of Loans, Net SUPPLEMENTAL DISCLOSURES FOR CASH FLOW INFORMATION: Supplemental Cash Flow Information [Abstract] HTM, at net carrying value Investment Securities Held-to-maturity Securities, Fair Value Disclosure Investment Securities Held-to-maturity Securities, Fair Value Disclosure PEO Name PEO Name 2-3 Years Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Three Borrowed Funds, Maturities, Repayments of Principal in Rolling Year Three Unrealized Gains (Losses) on Derivatives Realized net gain (loss) on interest rate swap derivatives Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Financial liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] More than 12 months, fair value Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Income taxes paid Income Tax Paid, before Refund Received Municipal loans Municipal Loans [Member] Class of financing receivables related to state, city or local governments or the agencies operated by state, city or local governments. Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Cash and due from banks Cash and Due from Banks Aging of past due loans by class of loan Financing Receivable, Past Due [Table Text Block] Financial Asset, Current Financial Asset, Not Past Due [Member] Debt Securities Debt Securities Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code BOLI Bank Owned Life Insurance Income Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Measurement Frequency [Domain] Measurement Frequency [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Stock compensation expense Share-Based Payment Arrangement, Noncash Expense Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] Fair Value, off-Balance-Sheet Risks, Disclosure Information [Line Items] Interest expense: Interest Expense, Operating and Nonoperating [Abstract] Salaries and employee benefits Labor and Related Expense Net loan paydowns (originations) Payments for (Proceeds from) Loans and Leases Net loss on premises and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Financing Receivable, Modified, Number Of Loans Financing Receivable, Modified, Number Of Loans Financing Receivable, Excluding Accrued Interest, Modified, Number Of Loans Modified in Nonaccrual Maturities, calls and principal repayments Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Earnings per common share - basic (in dollars per share) Earnings per common share - basic (in dollars per share) Earnings Per Share, Basic Insider Trading Arrangements [Line Items] BOLI Bank Owned Life Insurance Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Recoveries of loans charged-off Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] FHLB FHLB [Member] FHLB Cover [Abstract] Cover [Abstract] Accounting Changes and Reclassifications Reclassification, Comparability Adjustment [Policy Text Block] Loans and Leases Receivable Disclosure [Abstract] Loans and Leases Receivable Disclosure [Abstract] Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Equity Awards Adjustments Equity Awards Adjustments [Member] Hedging Relationship [Domain] Hedging Relationship [Domain] Mortgage-backed securities Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, without Single Maturity Date Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, without Single Maturity Date Deferred tax assets, net Deferred Tax Assets, Net Other interest earning assets Interest Income, Other Southside Statutory Trust IV Southside Statutory Trust IV [Member] Debt obligation for Southside Statutory Trust IV. Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Loans secured by farmland Commercial Real Estate, Farm Land Commercial Real Estate, Farm Land Other liabilities Increase (Decrease) in Other Operating Liabilities Pass Pass [Member] Loans by Portfolio Segment Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Unrealized gains and losses on securities transferred Securities Transferred Between Held-to-Maturity And Available-for-Sale Securities [Member] Securities Transferred Between Held-to-Maturity And Available-for-Sale Securities [Member] Trust preferred subordinated debentures, net of unamortized debt issuance costs Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust Other long-term debt Other Long-Term Debt Long-term Debt Long-Term Debt [Text Block] Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Items Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Demand Deposit Overdrafts Demand Deposit Overdrafts [Member] Demand Deposit Overdrafts Shareholders’ equity: Shareholders' equity: Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Federal Home Loan Bank borrowings maturities Federal Home Loan Bank, Advances, Maturities Summary, Maturity Range Represents the range of years until maturity from lowest to highest that are applicable to Federal Home Loan Bank outstanding as of the balance sheet date. Nonperforming assets by asset class Summary of nonperforming assets for the period [Table Text Block] Tabular disclosure of nonperforming assets. Commercial Commercial MBS Commercial Mortgage-Backed Securities [Member] Hedging Designation [Domain] Hedging Designation [Domain] Customer Counterparties Customer Counterparties [Member] Customer Counterparties [Member] Unsettled trades to sell securities Unsettled Trades to Sell Securities Amount of securities sold that were not settled by the end of the period. The amount recorded is the selling price including any accrued interest. This asset is collected upon delivery of the securities. Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Credit Loss Expense (Reversal) Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Credit Loss Expense (Reversal) Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Number of Loans Financing Receivable, Excluding Accrued Interest, Modified In Period, Number Of Contracts Financing Receivable, Excluding Accrued Interest, Modified In Period, Number Of Contracts Income Taxes Income Tax Disclosure [Text Block] OREO Real Estate Acquired Through Foreclosure Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Entity Filer Category Entity Filer Category Total fair value Debt Securities, Available-for-Sale, Unrealized Loss Position Federal Funds Purchased Federal Funds Purchased [Member] Due in one year or less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost Debt Securities, Held-to-maturity, Sale or Transfer of Investment [Abstract] Debt Securities, Held-to-Maturity, Sale or Transfer of Investment [Abstract] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] Derivatives designated as non-hedging instruments Not Designated as Hedging Instrument [Member] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Deposits: Deposits [Abstract] Unrealized and realized gains (losses) recognized in net income on equity investments Gain (Loss) on Securities [Table Text Block] Net derivatives included in the consolidated balance sheets Derivative liabilities Derivative Liability Entity Address, Address Line One Entity Address, Address Line One Operating lease right-of-use assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Other borrowings Line of Credit Facility, Fair Value of Amount Outstanding Income tax expense Tax benefit (expense) Income tax expense Income Tax Expense (Benefit) Fair Value Hedging Fair Value Hedging [Member] Loans charged-off Loans charged-off Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Basic and Diluted Earnings: Net Income (Loss) Attributable to Parent [Abstract] Loans secured by multi-family properties Commercial Real Estate, Multifamily Commercial Real Estate, Multifamily AOCI Attributable to Parent, Net of Tax AOCI Attributable to Parent, Net of Tax [Roll Forward] Unamortized Debt Issuance Expense Unamortized Debt Issuance Expense Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Statement [Table] Statement [Table] Proceeds from stock option exercises Proceeds from Stock Options Exercised Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Gross derivatives Derivative Asset, Subject to Master Netting Arrangement, before Offset Financial Institution Counterparties Financial Institution Counterparties [Member] Financial Institution Counterparties [Member] Debt Instruments [Abstract] Debt Instruments [Abstract] Loans held for sale Loan, Held-for-Sale, Fair Value Disclosure Due after one year through five years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after One through Five Years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, Before Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after One through Five Years Summary of Significant Accounting and Reporting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Secured Overnight Financing Rate (SOFR) [Member]