Document and Entity Information Document Information [Table] Document Information [Line Items] Document Type Document Quarterly Report Document Period End Date Document Transition Report Entity File Number Entity Registrant Name Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Title of 12(b) Security Trading Symbol Security Exchange Name Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Shell Company Entity Common Stock, Shares Outstanding Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Period Focus Entity Central Index Key Amendment Flag Consolidated Balance Sheets Statement [Table] Class of Financing Receivable, Type of Borrower [Axis] Class of Financing Receivable, Type of Borrower [Domain] Represents information pertaining to acquired loans. Acquired loans Acquired loans Represents information pertaining to Acquired - non-purchased credit deteriorated loans. Acquired - non-purchased credit deteriorated loans Acquired - non-purchased credit deteriorated loans Represents information pertaining to Acquired - purchased credit deteriorated loans. Acquired - purchased credit deteriorated loans Acquired - purchased credit deteriorated loans Represents information pertaining to non-acquired loans. Non-acquired loans Non-acquired loans Statement [Line Items] Deposits Accumulated Other Comprehensive Income (Loss) Assets: ASSETS Cash, Cash Equivalents, and Federal Funds Sold [Abstract] Cash and cash equivalents: Cash and Due from Banks Cash and due from banks Federal funds sold and interest-earning deposits with banks. Federal Funds Sold And Interest Earning Deposits With Banks Federal funds sold and interest-earning deposits with banks Interest-bearing Deposits in Banks and Other Financial Institutions Deposits in other financial institutions (restricted cash) Cash, Cash Equivalents, and Federal Funds Sold Total cash and cash equivalents Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). Trading Securities , Fair Value Trading securities, at fair value Marketable Securities [Abstract] Investment securities: Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Amortized Cost Securities held to maturity (fair value of $1,641,042 and $1,732,850) Amortized Cost Debt Securities, Available-for-Sale, Excluding Accrued Interest Securities available for sale Fair Value Securities available for sale, at fair value Other Investments Other investments Carrying Value Investments Total investment securities Carrying amount of the securities pledged to collateralize repurchase agreements Loans held for sale Loans held for sale Notes, Loans and Financing Receivable, Net, Current [Abstract] Loans: Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Total loans Total loans Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Less allowance for credit losses Less allowance for credit losses Balance at end of period Balance at beginning of period Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Loans held for investment, net of allowance for credit losses Loans, net Goodwill Goodwill Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Premises and equipment, net Bank Owned Life Insurance Bank owned life insurance ("BOLI") Deferred Income Tax Assets, Net Deferred tax assets Derivative Asset, Noncurrent Derivatives assets Estimated Fair Value Gain Core Deposit and Other Intangibles Core deposit and other intangibles Servicing Asset Mortgage servicing rights Other Assets. Other assets Assets Total assets Liabilities and Equity [Abstract] LIABILITIES AND SHAREHOLDERS' EQUITY Deposits, Interest-bearing and Noninterest-bearing, Alternative [Abstract] Deposits: Noninterest-bearing Deposit Liabilities Noninterest-bearing Interest-bearing Deposit Liabilities Interest-bearing Deposits. Total deposits Federal Funds Purchased Federal funds purchased Securities Sold under Agreements to Repurchase Securities sold under agreements to repurchase The carrying value as of balance sheet date of corporate and subordinated debentures. Corporate And Subordinated Debentures Corporate and subordinated debentures Advances from Federal Home Loan Banks Outstanding advances Other borrowings The carrying value as of balance sheet date for reserve for unfunded commitments. Reserve For Unfunded Commitments Reserve for unfunded commitments Derivative Liability Estimated Fair Value Loss Derivative liabilities Other Liabilities. Other liabilities Liabilities. Total liabilities Stockholders' Equity Attributable to Parent [Abstract] Shareholders' equity: Common Stock, Value, Issued Common stock - $2.50 par value; authorized 160,000,000 shares; 96,971,142 and 99,138,204 shares issued and outstanding, respectively Additional Paid in Capital Surplus Retained Earnings (Accumulated Deficit) Retained earnings Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Stockholders' Equity Attributable to Parent Balance Balance Total shareholders' equity Liabilities and Equity Total liabilities and shareholders' equity Held-to-maturity Securities, Fair Value Securities held to maturity, fair value (in dollars) Fair Value Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Balance (in shares) Balance (in shares) Common stock, shares outstanding Consolidated Statements of Income Product and Service [Axis] Product and Service [Domain] Fees on deposit accounts Fees on deposit accounts Mortgage banking income Mortgage banking income Trust and investment services income Trust and investment services income Represents information pertaining to Correspondent banking and capital market income. Correspondent banking and capital markets income Correspondent banking and capital markets income Represents the information pertaining to Small Business Administration Income. SBA income SBA income Interest and Dividend Income, Operating [Abstract] Interest income: Interest and Fee Income, Loans and Leases Loans, including fees Interest and Dividend Income, Securities, by Taxable Status [Abstract] Investment securities: Interest Income, Securities, Operating, Taxable Taxable Interest Income, Securities, Operating, Tax Exempt Tax-exempt Interest Income, Federal Funds Sold and Securities Purchased under Agreements to Resell Federal funds sold, securities purchased under agreements to resell and interest-bearing deposits with banks Interest and Dividend Income, Operating Interest income Total interest income Interest Expense, Operating [Abstract] Interest expense: Interest Expense, Deposits Deposits Interest Expense, Federal Funds Purchased and Securities Sold under Agreements to Repurchase Federal funds purchased and securities sold under agreements to repurchase Interest Expense, Subordinated Notes and Debentures Corporate and subordinated debentures Interest Expense, Other Long-Term Debt Other borrowings Interest Expense, Operating Interest expense Total interest expense Interest Income (Expense), Net Net interest income (a) Net interest income Provision for Loan Losses Expensed Provision for credit losses Interest Income (Expense), after Provision for Loan Loss Net interest income after provision for credit losses Net interest income after provision for credit losses Total noninterest income Noninterest income: Revenue from Contract with Customer, Excluding Assessed Tax Noninterest income Debt and Equity Securities, Realized Gain (Loss) Securities losses, net Securities (losses) gain, net Sale and Leaseback Transaction, Gain (Loss), Net Gain on sale-leaseback, net of transaction costs Gain on sale-leaseback, net of transaction costs Noninterest Income, Other Other income Noninterest Income Total noninterest income Noninterest Expense [Abstract] Noninterest expense: Total noninterest expense Labor and Related Expense Salaries and employee benefits Salaries and employee benefits Information Technology and Data Processing Information services expense This element represents the net gain or loss resulting from sales and other disposals of other real estate owned and write-downs of other real estate owned after acquisition or physical possession. Other Real Estate Owned Expense and Loan Related OREO and loan related expense Occupancy, Net Occupancy expense Business Combination, Integration Related Costs Merger, branch consolidation, severance-related, and other expense Merger and branch consolidation related expense Federal Deposit Insurance Corporation Premium Expense FDIC assessment and other regulatory charges Supplies and Postage Expense Supplies, printing and postage expense Amortization of Intangible Assets Amortization of intangibles Amortization expense Professional Fees Professional fees Marketing and Advertising Expense Advertising and marketing Other Noninterest Expense Other expense Noninterest Expense Total noninterest expense Earnings [Abstract] Earnings: Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income tax provision Income before provision for income taxes Income Tax Expense (Benefit) Provision for income taxes Income tax provision Provision for income taxes Net income (GAAP) Net income Net income Earnings Per Share Earnings per common share: Basic earnings (loss) per common share (in dollars per share) Basic (in dollars per share) Basic earnings per common share (in dollars per share) Earnings Per Share, Diluted Diluted (in dollars per share) Diluted earnings per common share (in dollars per share) Weighted Average Number of Shares Outstanding, Basic [Abstract] Weighted average common shares outstanding: Weighted-average basic common shares Basic (in shares) Weighted-average basic common shares Weighted Average Number of Shares Outstanding, Diluted Diluted (in shares) Weighted-average dilutive shares Consolidated Statements of Comprehensive Income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent [Abstract] Unrealized holding gains (losses) on available for sale securities: Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Unrealized holding gains (losses) arising during period Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Tax effect Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Reclassification adjustment for net loss included in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Tax effect Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Net of tax amount Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Net comprehensive income (loss) Other comprehensive income (loss), net of tax Other comprehensive income (loss), net of tax effects Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income Consolidated Statements of Changes in Shareholders' Equity Equity Components [Axis] Equity Component [Domain] Common Stock Common Stock Surplus Surplus Retained Earnings Retained Earnings AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Income (Loss) Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity Accumulated Other Comprehensive Income (Loss) Dividends, Common Stock, Cash Cash dividends declared on common stock per share Dividend, Share-based Payment Arrangement, Cash Cash dividend equivalents paid on restricted stock units Stock Issued During Period, Value, Employee Stock Purchase Plan Employee stock purchases Stock Issued During Period, Shares, Employee Stock Purchase Plans Employee stock purchases (in shares) Stock Issued During Period, Value, Stock Options Exercised Stock options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercised (in shares) Stock options exercised (in shares) Reflects the value of stock issued pursuant to restricted stock units. Value Of Stock Issued Pursuant To Restricted Stock Units Stock issued pursuant to restricted stock units Reflects the number of stock issued pursuant to restricted stock units. Number Of Stock Issued Pursuant To Restricted Stock Units Stock issued pursuant to restricted stock units (in shares) Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Stock issued in lieu of cash - directors fees Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Stock issued in lieu of cash - directors fees (in shares) Stock Redeemed or Called During Period, Value Common stock repurchased - buyback plan Stock Redeemed or Called During Period, Shares Common stock repurchased - buyback plan (in shares) Stock Repurchased During Period, Value Common stock repurchased - equity plans Cost of shares repurchased under other arrangements Stock Repurchased During Period, Shares Common stock repurchased - equity plans (in shares) Number of shares repurchased Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Share-based compensation expense Amount of decrease in the additional paid in capital as a result of excise tax on share repurchased during the period. Adjustments To Additional Paid In Capital, Share Repurchase, Excise Tax Excise tax on repurchase of common stock Stock Issued During Period, Value, Acquisitions Common stock issued for Independent Bank Group, Inc. ("Independent") acquisition Stock Issued During Period, Shares, Acquisitions Common stock issued for Independent Bank Group, Inc. ("Independent") acquisition (in shares) Common Stock, Dividends, Per Share, Declared Common stock cash dividends declared, per share (in dollars per share) Cash dividends declared (in dollars per share) Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Cash flows from operating activities: Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by (used in) operating activities: The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets other than amortization of debt discount or (premium). Depreciation, Depletion and Amortization, Other Than Amortization of Debt Discount (Premium) Depreciation and amortization Deferred Income Taxes and Tax Credits Deferred income taxes Gain (Loss) on Sale of Investments Losses on sale of securities, net Share-based Compensation. Share-based compensation expense The accretion on loans covered under FDIC loss share agreements that is recognized in earnings over the term of the FDIC loss-sharing agreement. Accretion on Loans Covered under Fdic Loss Share Agreements Accretion of discount related to acquired loans Gain (Loss) on Disposition of Property Plant Equipment Losses (gains) on disposal of premises and equipment Gains (Losses) on Sales of Other Real Estate Gains on sale of bank properties held for sale and repossessed real estate Accretion (Amortization) of Discounts and Premiums, Investments Net amortization of premiums and discounts on investment securities Represents the amount of other real estate write downs adjusted back to net income. Other Real Estate Write Downs Bank properties held for sale and repossessed real estate write downs Represents the fair value adjustment for loans held for sale during the period. Fair Value Adjustment For Loans Held For Sale Fair value adjustment for loans held for sale