Consolidated Entities [Axis] Consolidated Entities [Axis] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Proceeds from sales of securities available-for-sale Proceeds from Sale of Debt Securities, Available-for-Sale Entity Voluntary Filers Entity Voluntary Filers Allowance for credit losses on loans: Financing Receivable, Allowance for Credit Loss [Roll Forward] Amortization expense, rolling year five Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Five C&I C&I [Member] C&I [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Award Type [Domain] Award Type [Domain] Noninterest-bearing Noninterest-Bearing Deposit Liabilities Schedule of Stock Appreciation Right Activity Share-Based Payment Arrangement, Stock Appreciation Right, Activity [Table Text Block] Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Tier I capital (to average assets), requirement to be well-capitalized, amount Banking Regulation, Tier 1 Leverage Capital, Well Capitalized, Minimum Pension Plans Pension and Other Postretirement Plans, Policy [Policy Text Block] Unused Available Lines of Credit Debt Disclosure [Text Block] Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Payments to acquire assets Asset acquisition of TouchPoint Payments to Acquire Businesses, Gross Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] 401(k) employer contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Data processing services Information Technology and Data Processing Accounts and drafts payable Accounts and drafts payable Accounts And Drafts Payable, Carrying Amount Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business and includes carrying value of amounts due on drafts payable on the balance sheet date. $250 or more Interest Expense Time Deposits 250000 or More Interest expense incurred on time deposits, including certificates of deposits, of $250,000 or more in domestic offices. Taxable Interest Income, Securities, Operating, Taxable Real Estate, Faith-Based, Mortgage Real Estate Faith-based Mortgage [Member] Real Estate Faith-based Mortgage [Member] Performance-based Restricted Stock Performance Shares [Member] Segment Reporting [Abstract] Segment Reporting [Abstract] Real estate investment trusts Real Estate Defined Benefit Plan, Real Estate [Member] Amortization expense, next rolling twelve months Finite-Lived Intangible Assets, Amortization Expense, Next Rolling 12 Months Net (decrease) increase in noninterest-bearing demand deposits Net Increase (Decrease) In Noninterest-Bearing Demand Deposits Net change during the reporting period in noninterest-bearing demand deposits. Equipment Equipment Expense Lease liability Deferred Tax Asset, Lease Liability Deferred Tax Asset, Lease Liability Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Tier I capital (to risk-weighted assets), capital requirements, ratio Tier I capital (to risk-weighted assets), capital requirements ratio The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Common equity tier I capital (to risk-weighted assets), requirement to be well-capitalized, ratio Common Equity Tier I Capital (to risk-weighted assets), requirement to be well capitalized ratio The Common Equity Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. 4-5 years Lessee, Operating Lease, Liability, to be Paid, Year Five Construction Construction [Member] Current Financial Asset, Not Past Due [Member] Accounting Policies [Line Items] Accounting Policies [Line Items] Accounting Policies Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Income Taxes Income Tax Disclosure [Text Block] Industry Sector [Domain] Industry Sector [Domain] 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Five Total capital (to risk-weighted assets), capital requirements, amount Banking Regulation, Total Risk-Based Capital, Capital Adequacy, Minimum Issuance of common shares pursuant to stock-based compensation plan, net (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, before Forfeiture Expenses paid from plan assets Defined Benefit Plan, Plan Assets, Administration Expense Geographic Distribution [Domain] Geographic Distribution [Domain] Federal Deferred Federal Income Tax Expense (Benefit) Nonperforming Loans Subject To Special Monitoring Nonperforming Loans Subject To Special Monitoring [Member] Nonperforming Loans Subject To Special Monitoring [Member] Opportunistic Opportunistic [Member] Opportunistic [Member] Preferred stock, par or stated value per share (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, par value $0.50 per share; 2,000,000 shares authorized and no shares issued Preferred Stock, Value, Issued PPP Paycheck protection program ("PPP") [Member] Paycheck protection program ("PPP") [Member] Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Cash dividends paid Payments of Ordinary Dividends, Common Stock Diluted Earnings Per Share (in dollars per share) Earnings Per Share, Diluted Loans, net Loans, net Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Common shares in treasury, at cost (1,923,397 shares at December 31, 2023 and 1,836,116 shares at December 31, 2022, respectively) Treasury Stock, Value Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Foreclosed Assets Financing Receivable, Held-for-Investment, Foreclosed Asset [Policy Text Block] Treasury stock (in shares) Treasury Stock, Common, Shares Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] 2024 Defined Benefit Plan, Expected Future Benefit Payment, Year One Total Time Deposits, Weighted Average Interest Rate, Aggregate Aggregate percentage of weighted average interest rate for time deposits held by the entity with maturities from one to five years. Securities available-for-sale, at fair value Fair Value Total Debt Securities, Available-for-Sale, Excluding Accrued Interest Due after 5 years through 10 years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Exercise of SARs Stock Issued During Period, Value, Stock Options Exercised Interest Income: Interest and Dividend Income, Operating [Abstract] Trading Symbol Trading Symbol Cass Commercial Bank Cass Commercial Bank [Member] Cass Commercial Bank [Member] Net income Net income Net Income (Loss) Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] 90 Days and Over Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Due after 1 year through 5 years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Leases Lessee, Operating Leases [Text Block] Benefits paid Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Corporate bonds Corporate Bond Securities [Member] Liabilities and Shareholders’ Equity Liabilities and Equity [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Interest on federal funds sold and other short-term investments Interest on federal funds sold and other short-term investments Interest income on federal funds sold and other short-term investments. Condensed Financial Information of Parent Company Condensed Financial Information of Parent Company Only Disclosure [Text Block] Investment Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Shareholders’ Equity: Equity, Attributable to Parent [Abstract] Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Schedule of Unrecognized Tax Benefits Roll Forward Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Allowance for unfunded commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Other Other Intangible Assets [Member] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Service cost Service cost – benefits earned during the year Defined Benefit Plan, Service Cost Award vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Restricted securities Debt Securities, Available-for-Sale, Restricted Performance-based stock vested Performance Based Stock Performance-based stock. Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Emerging Markets Emerging Markets [Member] Emerging Markets [Member]. Two years Time Deposits, Weighted Average Interest Rate, Maturities Year Two Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Other Commitments [Table] Other Commitments [Table] Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Total deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Patent Patents [Member] Interest Expense: Interest Expense [Abstract] One year Time Deposits, Weighted Average Interest Rate, Maturities Year One Carrying Amount Reported Value Measurement [Member] Number of troubled debt restructured loans subsequently defaulted Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts Time deposits: Interest Expense, Time Deposits [Abstract] Performing Loans Subject To Special Monitoring Performing Loans Subject To Special Monitoring [Member] Performing Loans Subject To Special Monitoring [Member] Goodwill Goodwill Changes in unrecognized tax benefits as a result of tax positions taken during a prior year Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Equity Components [Axis] Equity Components [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Allowance for Credit Losses Credit Loss, Financial Instrument [Policy Text Block] Measurement Basis [Axis] Measurement Basis [Axis] Amortization of restricted stock bonus Amortization of restricted stock bonus Amount of amortization of the restricted stock bonus. Less allowance for credit losses Beginning balance Ending balance Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Entity Small Business Entity Small Business (Reductions) increases resulting from: (Reductions) increases resulting from: (Reductions) increases resulting from: Local Phone Number Local Phone Number Increase in accounts receivable Increase (Decrease) in Accounts Receivable Fair Value Measurement [Domain] Fair Value Measurement [Domain] Estimated Forecast [Member] Collateral Held [Axis] Collateral Held [Axis] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Extended Maturity Extended Maturity [Member] Funded status: Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Common equity tier I capital (to risk-weighted assets), capital requirements, ratio Common Equity Tier I Capital (to risk-weighted assets), capital requirements ratio The minimum Common Equity Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. Schedule of Restricted Stock Activity Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Depreciation Depreciation Share-based compensation adjustment Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-Based Payment Arrangement, Amount Retirement Benefits [Abstract] Retirement Benefits [Abstract] Purchase of common shares (in shares) Stock Issued During Period, Shares, Purchase of Assets Processing fees Processing Fees [Member] Processing Fees Type of Borrower [Axis] Type of Borrower [Axis] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Balance sheet assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] Schedule of Plan's Pension Costs Schedule of Plan's Pension Costs [Table Text Block] Tabular disclosure of net periodic pension costs. Total intangible assets, net Intangible Assets, Net (Including Goodwill) Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Effect of dilutive restricted stock, performance based restricted stock (“PBRS”), and SARs (in shares) Weighted Average Number of Shares Outstanding, Diluted, Adjustment Projected benefit obligation: Benefit obligation: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Information Services Information Services [Member] Information Services [Member] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Due after 10 years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Total net revenue Revenues Prepaid expenses Deferred Tax Liabilities, Prepaid Expenses Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Product and Service [Domain] Product and Service [Domain] Other Other Expenses Shares forfeited Shares Issued, Shares, Share-Based Payment Arrangement, Forfeited Standby letters of credit Standby Letters of Credit [Member] Loans Excluding Unfunded Commitments Loans Excluding Unfunded Commitments [Member] Loans Excluding Unfunded Commitments Cash Flows From Investing Activities: Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Award Type [Axis] Award Type [Axis] Capital Requirements and Regulatory Restrictions Regulatory Capital Requirements under Banking Regulations [Text Block] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Real Estate, Faith-based, Construction Real Estate Faith-based Construction [Member] Real Estate Faith-based Construction [Member] Tax-equivalized pre-tax income Income (Loss) from Continuing Operations Including Tax Equivalent Adjustment, Before Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations Including Tax Equivalent Adjustment, Before Income Taxes, Noncontrolling Interest Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Less than $100 Time Deposits, Less than $100,000 Total capital (to risk weighted assets), requirement to be well-capitalized, ratio Total capital (to risk-weighted assets), requirement to be well capitalized ratio The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action. Total interest expense Interest expense Interest Expense Tier I capital (to risk-weighted assets), capital requirements, amount Banking Regulation, Tier 1 Risk-Based Capital, Capital Adequacy, Minimum Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Number of shares authorized (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Premises and equipment, gross Property, Plant and Equipment, Gross Loans Financing Receivable [Policy Text Block] Discount on cash flows Lessee, Operating Lease, Liability, Undiscounted Excess Amount Employer contribution Defined Benefit Plan, Plan Assets, Contributions by Employer Savings deposits Interest Expense, Savings Deposits Schedule of Performance Shares Activity Share-Based Payment Arrangement, Performance Shares, Outstanding Activity [Table Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Tier I capital (to average assets), capital requirements, ratio Tier I capital (to average assets), capital requirements ratio The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations. Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Four years Time Deposits, Weighted Average Interest Rate, Maturities Year Four Uninsured scheduled maturities, year one Time Deposit Liability Uninsured, Maturity, Within Year One Time Deposit Liability Uninsured, Maturity, Within Year One Schedule of Other Operating Cost and Expense, by Component Schedule of Other Operating Cost and Expense, by Component [Table Text Block] Entity File Number Entity File Number Net (decrease) increase in interest-bearing demand and savings deposits Net Increase (Decrease) In Interest-Bearing Demand And Savings Deposits Net change during the reporting period in interest-bearing demand and savings deposits. Deposits Deposits, by Type [Abstract] Commercial and standby letters of credit, remaining duration, term Commercial And Standby Letters Of Credit, Remaining Duration, Term Commercial And Standby Letters Of Credit, Remaining Duration, Term Software Software Computer Software, Intangible Asset [Member] One year Time Deposit Maturities, Year One Changes in unrecognized tax benefits as a result of tax positions taken during a prior year Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Auditor Firm ID Auditor Firm ID Financial fees Bank Service Fees [Member] Bank Service Fees Amortization of intangible assets Amortization of Intangible Assets Entity Shell Company Entity Shell Company 2-3 years Lessee, Operating Lease, Liability, to be Paid, Year Three Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Impact of New and Not Yet Adopted Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Other income (out-of-scope of ASC 606) Other fees Revenue Not from Contract with Customer (Decrease) increase in current income tax liability Increase (Decrease) in Income Taxes Payable Changes in unrecognized tax benefits as a result of tax position taken during the current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Increase (Decrease) in Other Operating Liabilities Increase (Decrease) in Other Operating Liabilities Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Plan assets, measurement input Defined Benefit Plan, Plan Assets, Measurement Input Defined Benefit Plan, Plan Assets, Measurement Input Accumulated Amortization Total intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization 1-2 years Lessee, Operating Lease, Liability, to be Paid, Year Two Time deposits: Time Deposits [Abstract] Operating lease, cost Operating Lease, Cost Unamortized intangible assets: Unamortized intangible assets: Unamortized Intangible Asset AFS, 12 months or more, Estimated Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Common stock, shares issued (in shares) Common Stock, Shares, Issued Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Net actuarial loss (gain) Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Unrealized Gain (Loss) on Investments Unrealized Gain (Loss) on Investments [Table Text Block] Security Exchange Name Security Exchange Name Total Assets, Fair Value Disclosure AFS, Total Unrealized Losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Stock-Based Compensation Share-Based Payment Arrangement [Policy Text Block] Available-for-sale securities, number of positions, greater than one year Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Percentage of shares vested Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Lease payments due Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Unrecognized compensation expense, period for recognition Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Other financing activities, net Proceeds from (Payments for) Other Financing Activities Maximum Maximum [Member] Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent U.S. Large Cap Passive U.S. Large Cap Passive [Member] United States Large Cap Passive [Member]. Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Unrecognized compensation expense Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Document Type Document Type Schedule of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Accrued pension liability Defined Benefit Plan, Funded (Unfunded) Status of Plan Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Number Short-term lease, cost Short-Term Lease, Cost Accounts and drafts receivable from customers Receivables from Customers Entity Address, Address Line One Entity Address, Address Line One Purchase of common shares Treasury Stock, Value, Acquired, Cost Method Entity Address, Address Line Two Entity Address, Address Line Two Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Exempt from federal income taxes Interest Income, Securities, Operating, Tax Exempt Common equity tier I capital (to risk-weighted assets), requirement to be well-capitalized, amount Common Equity Tier I Capital (to risk-weighted assets), requirement to be well capitalized amount The amount of Common Equity Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. Balance sheet liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Summary of ACL by Category Summary of Allowance For Credit Loss by Category [Table Text Block] Summary of ACL by Category. Number of loans individually evaluated for impairment Number Of Loans Individually Evaluated for Impairment Number Of Loans Individually Evaluated for Impairment Losses (gains) on sales of securities Debt and Equity Securities, Gain (Loss) Schedule of Assumed Long-term Rate of Return on Assets Schedule of Assumed Long-term Rate of Return on Assets [Table Text Block] Tabular disclosure for assumed long term rate of return on assets. Stock-based Compensation Share-Based Payment Arrangement [Text Block] Federal Current Federal Tax Expense (Benefit) Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Purchases of securities available-for-sale Proceeds from sales of securities available-for-sale Payments to Acquire Debt Securities, Available-for-Sale Unfunded Loan Commitment Unfunded Loan Commitment [Member] Business Acquisition [Axis] Business Acquisition [Axis] Accrued interest payable Accrued Liabilities, Fair Value Disclosure Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Total capital (to risk-weighted assets), actual, amount Banking Regulation, Total Capital, Actual Total Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Schedule of Line of Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] State Deferred State and Local Income Tax Expense (Benefit) Income Statement [Abstract] Income Statement [Abstract] $100 to less than $250 Time Deposits, More than $100,000 Less than $250,000 The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more and total to less than $250,000. Shares issued (in shares) Stock Issued During Period, Shares, New Issues Title of 12(b) Security Title of 12(b) Security Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Goodwill, gross carrying amount Goodwill, Gross Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss Two years Time Deposit Maturities, Year Two Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Six Corresponding Banks Six Corresponding Banks [Member] Six Corresponding Banks Actuarial gain Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Class of Financing Receivable, Type of Borrower [Domain] Class of Financing Receivable, Type of Borrower [Domain] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Three years Time Deposits, Weighted Average Interest Rate, Maturities Year Three Operating Segments Operating Segments [Member] Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Issuance of common shares pursuant to stock-based compensation plan, net Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Expected income tax expense Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Diluted: Earnings Per Share, Diluted [Abstract] Tax effect OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Amortization [Abstract] Amortization [Abstract] Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Entity Tax Identification Number Entity Tax Identification Number Two Corresponding Banks Two Corresponding Banks [Member] Two Corresponding Banks Land Land [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Industry Sector [Axis] Industry Sector [Axis] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Financial Instrument [Axis] Financial Instrument [Axis] CRE CRE [Member] CRE [Member] Unappropriated retained earnings Retained Earnings, Unappropriated Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Entity Interactive Data Current Entity Interactive Data Current Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Total loans Total Loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss, Current Product Product [Member] Outside service fees Outside service fees Outside service fees. Purchase of common shares for treasury Payments for Repurchase of Common Stock Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Condensed Balance Sheet Condensed Balance Sheet [Table Text Block] Core Fixed Income Fixed Income Funds [Member] Tax effect Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Segments [Domain] Segments [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Four years Time Deposit Maturities, Year Four Retained earnings Retained Earnings (Accumulated Deficit) Employee restricted stock grants Stock Issued During Period, Shares, Restricted Stock Award, Gross Collateral Held [Domain] Collateral Held [Domain] Cass Information Systems, Inc. Cass Information Systems Inc. [Member] Cass Information Systems Inc. [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Plan assets: Plan assets: Plan assets: Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Over 5 years Lessee, Operating Lease, Liability, to be Paid, Due after Year Four Lessee, Operating Lease, Liability, to be Paid, Due after Year Four Deferred tax liabilities: Deferred Tax Liabilities, Net [Abstract] Leases [Abstract] Leases [Abstract] Other Commitments [Line Items] Other Commitments [Line Items] Total fee revenue and other income Fee income Noninterest Income Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Entity Address, State or Province Entity Address, State or Province Cash Flows From Operating Activities: Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Faith-based CRE Faith-based CRE [Member] Faith-based CRE [Member] Operating lease, payments Operating Lease, Payments SERP Supplemental Executive Retirement Plan [Member] Supplemental Executive Retirement Plan [Member]. Common stock, shares, outstanding (in shares) Common Stock, Shares, Outstanding Proceeds from maturities of securities available-for-sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Basic: Earnings Per Share, Basic [Abstract] Interest cost Interest cost on projected benefit obligations Defined Benefit Plan, Interest Cost Treasury Stock Treasury Stock [Policy Text Block] Disclosure of accounting policy for an entity's treasury stock, including the average cost per share, carrying basis for each class of treasury stock, description of share repurchase program authorized by an entity's board of directors, the number of shares repurchased, the cost of the shares repurchased, the remaining maximum dollar value of shares available for repurchase under the program, the treatment of the purchase price in excess of the current market value, number of shares held for each class of treasury stock, and other information necessary to a fair presentation. Other Income and Expenses [Abstract] Other Income and Expenses [Abstract] Auditor Location Auditor Location Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Employee Benefit Plans Retirement Benefits [Text Block] Condensed Income Statement Condensed Income Statement [Table Text Block] Schedule of Common Stock Outstanding Roll Forward Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Customer lists Customer Lists [Member] Shares outstanding at January 1 Shares outstanding at December 31 Shares, Outstanding Other operating activities, net Other, net Other Operating Activities, Cash Flow Statement Interest and dividends on securities: Interest and Dividend Income, Securities, by Taxable Status [Abstract] State taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Common stock, par or stated value (in dollars per share) Common Stock, Par or Stated Value Per Share Tax effect Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Percentage of target opportunity for awards to vest Percentage of target opportunity for awards to vest Percentage of target opportunity for awards to vest. Finance receivable, related parties Loans and Leases Receivable, Related Parties Available-for-sale securities, percentage of total securities Available-For-Sale, Securities In Unrealized Loss Positions, Percentage Of Total Securities The percentage of the number of investment positions in the available-for-sale investments determined to be temporarily impaired. Profit sharing expense Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Available-for-sale securities, number of positions Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Supplemental executive retirement plan accrual Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits Effective tax rate Effective Income Tax Rate Reconciliation, Percent Operating lease, liability Total lease liability Operating Lease, Liability Measurement Input Type [Domain] Measurement Input Type [Domain] Amortization expense, rolling year two Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Two FASB ASC 715 pension adjustment Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Credit Facility [Axis] Credit Facility [Axis] Net unrealized gain (loss) on securities available-for-sale OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax Total liabilities Total liabilities Liabilities Service Service [Member] Tier I capital (to risk-weighted assets), actual, ratio Tier I capital (to risk-weighted assets), actual ratio Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework. Adjusted Balance Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] AFS, Total Estimated Fair Value Debt Securities, Available-for-Sale, Unrealized Loss Position Cash and cash equivalents Cash, Cash Equivalents, and Short-Term Investments Premises and Equipment Property, Plant and Equipment Disclosure [Text Block] Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Total operating expense Noninterest Expense Total Time Deposits Other Other Loan [Member] Other Loan Research and development expenses Deferred Tax Assets, in Process Research and Development Debt Disclosure [Abstract] Debt Disclosure [Abstract] Common equity tier I capital (to risk-weighted assets), actual, ratio Common Equity Tier I Capital (to risk-weighted assets), actual ratio Common Equity Tier 1 capital divided by risk weighted assets as defined by regulations. Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Tier I capital (to risk-weighted assets), requirement to be well-capitalized, ratio Tier I capital (to risk-weighted assets), requirement to be well capitalized ratio The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. Interest-Bearing Deposits [Abstract] Interest-Bearing Deposits [Abstract] Interest-Bearing Deposits [Abstract] Number of reportable segments Number of Reportable Segments Earnings Per Share [Abstract] Earnings Per Share [Abstract] SARs Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] 2025 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Reduction of tax benefits over the next twelve months Decrease in Unrecognized Tax Benefits is Reasonably Possible AFS, Less than 12 months, Estimated Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Due after 1 year through 5 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Interest and fees on loans Interest and Fee Income, Loans and Leases Trade Name Trade Names [Member] Global Equity International (Developed) [Member] Foreign Equity Securities Developed [Member] Tier I capital (to average assets), requirement to be well-capitalized, ratio Tier I capital (to average assets), requirement to be well capitalized ratio The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action. Operating Expense: Noninterest Expense [Abstract] Payments in advance of funding Payments In Advance Of Funding The normal cycle for payment of Transportation invoices to a carrier, on behalf of the company's customer, is: the customer provides the funds to the company prior to the payment of the invoice by the company to the carrier. Payments in excess of funding are generated when, according to a service agreement with a few selected carriers, the company pays the carrier prior to receipt of the funds from the customer. The company receives a fee from the carrier for making this accelerated payment. State Current State and Local Tax Expense (Benefit) Investments in subsidiaries Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other intangible assets, net Other Intangible Assets, Net Schedule of Maturities of Time Deposits Schedule of Maturities of Time Deposits [Table Text Block] Schedule of maturities of time deposits. Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Net increase (decrease) in time deposits Increase (Decrease) in Time Deposits Savings deposits Deposits, Savings Deposits Mortgage-backed securities issued or guaranteed by U.S. government agencies or sponsored enterprises Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Extended Maturity and Interest Rate Reduction Extended Maturity and Interest Rate Reduction [Member] Supplemental information: Supplemental Cash Flow Information [Abstract] Release of credit losses for unfunded commitments Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Entity Filer Category Entity Filer Category Statement [Table] Statement [Table] Other liabilities Other Liabilities Current Fiscal Year End Date Current Fiscal Year End Date Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Acquired Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Shares repurchased Stock Repurchased During Period, Shares Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Balance at January 1 Balance at December 31 Unrecognized Tax Benefits One-Year Nominal Return One-Year Nominal Return The expected percentage of one-year nominal return on assets. Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Condensed Financial Information Disclosure [Abstract] Condensed Financial Information Disclosure [Abstract] Intangible assets Deferred Tax Liabilities, Other Finite-Lived Assets Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Granted in period, weighted average fair value (in dollars per share) Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value 2029-2033 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Buildings Building [Member] Participating Mortgage Loans [Table] Participating Mortgage Loans [Table] Asset backed securities issued or guaranteed by U.S. Government agencies or sponsored enterprises Asset-Backed Securities [Member] Banking Services Banking Services [Member] Banking Services [Member] Marketable Securities [Line Items] Marketable Securities [Line Items] Stock compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-Based Compensation Cost Summary of Loan Categories Summary of Loan Categories [Table Text Block] Tabular disclosure for loan categories. Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Tier I capital (to risk-weighted assets), actual, amount Common Equity Tier I Capital (to risk-weighted assets), actual amount Common Equity Tier 1 Risk Based Capital as defined in the regulations. Net amortization and deferral Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Accrued interest receivable Accrued Interest Receivable, Fair Value Disclosure Accrued Interest Receivable, Fair Value Disclosure ASC 715 pension funding liability Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Furniture, fixtures and equipment Furniture and Fixtures [Member] Pension Deferred Tax Liabilities Pension Costs Deferred tax liabilities, pension costs. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Total shareholders’ equity Beginning balance Ending balance Total shareholders’ equity Equity, Attributable to Parent Available-for-sale securities, gross realized gains Debt Securities, Available-for-Sale, Realized Gain Consolidation Items [Axis] Consolidation Items [Axis] Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate First Seven Years Of Service SERP, Year One Through Seven [Member] SERP, Year One Through Seven Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Restricted Stock Restricted Stock [Member] Leasehold improvements Leaseholds and Leasehold Improvements [Member] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Promotional expense Marketing and Advertising Expense Finite Lived Intangible Assets Major Class Name Domain Finite-Lived Intangible Assets, Major Class Name [Domain] Foreign currency translation adjustments, net of tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Expenses: Expenses: Expenses: Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] U.S. Small/Mid Cap Growth U.S. Small/Mid Cap Growth [Member] United States Small And Mid Cap Growth [Member]. Subsequent Events [Abstract] Subsequent Events [Abstract] Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Condensed Cash Flow Statement Condensed Cash Flow Statement [Table Text Block] Pension Plan, Year One Through Seven Pension Plan, Year One Through Seven [Member] Pension Plan, Year One Through Seven Geographic Distribution [Axis] Geographic Distribution [Axis] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Net decrease (increase) in loans Payments for (Proceeds from) Loans and Leases Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] State and political subdivisions US States and Political Subdivisions Debt Securities [Member] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Entity Emerging Growth Company Entity Emerging Growth Company Fair Value Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Allowance for credit losses Deferred Tax Asset, Tax Deferred Expense, Reserve and Accrual, Financing Receivable, Allowance for Credit Loss Non-U. S. Core Non-U.S. Core [Member] Non United States Core [Member]. Other intangible assets, net Other intangible assets, net Intangible Assets, Net (Excluding Goodwill) Corporate, Eliminations and Other Corporate, Reconciling Items, And Eliminations [Member] Corporate, Reconciling Items, And Eliminations Condensed Income Statement [Table] Condensed Income Statement [Table] Five years Time Deposits, Weighted Average Interest Rate, Maturities Year Five Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Parent Company Parent Company [Member] Document Fiscal Period Focus Document Fiscal Period Focus Interest-Bearing Deposits Deposit Liabilities Disclosures [Text Block] Less than 1 year Lessee, Operating Lease, Liability, to be Paid, Year One Finite-lived, intangible assets, useful life Finite-Lived Intangible Asset, Useful Life Average funding sources Average Funding Sources Average Funding Sources 3-4 years Lessee, Operating Lease, Liability, to be Paid, Year Four Non-option equity instruments, granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted Schedule of Interest on Deposits Schedule of Interest on Deposits [Table Text Block] Tabular disclosure of interest expense on deposit accounts. Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Net interest income after (release of) provision for credit losses Net interest income after provision for (release of) credit losses Interest Income (Expense), after Provision for Loan Loss Common Stock Common Stock [Member] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Interest Bearing Deposits Schedule of Interest Bearing Deposits [Table Text Block] Tabular disclosure of interest bearing deposits. City Area Code City Area Code Entity Address, Postal Zip Code Entity Address, Postal Zip Code Asset acquisition of TouchPoint Payments for Asset Acquisitions Payments for Asset Acquisitions Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Common Stock and Earnings per Share Earnings Per Share [Text Block] Product and Service [Axis] Product and Service [Axis] Reductions to unrecognized tax benefits as a result of a lapse of the applicable statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Commitments to extend credit Commitments to Extend Credit [Member] Other operating Total other operating expense Other Noninterest Expense Employee SARs exercised Employee SARs exercised Number of share options and stock appreciation rights exercised during the current period. Document Fiscal Year Focus Document Fiscal Year Focus Tax-exempt income Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Weighted Average Exercise Price Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Marketable Securities [Table] Marketable Securities [Table] Total capital (to risk-weighted assets), capital requirements, ratio Total capital (to risk-weighted assets), capital requirements ratio The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. Total deposits Deposits Interest-bearing Total Interest-Bearing Deposit Liabilities Minimum Minimum [Member] Premises and equipment, net Total premises and equipment, net Property, Plant and Equipment, Net Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Tier I capital (to average assets), capital requirements, amount Banking Regulation, Tier 1 Leverage Capital, Capital Adequacy, Minimum Receivables [Abstract] Receivables [Abstract] Annual Standard Deviation Annual Standard Deviation The expected percentage of annual standard deviation on assets. Percent of Total Weighted Average Rate of Time Deposits [Abstract] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Cash dividends (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Beginning balance Ending balance Defined Benefit Plan, Benefit Obligation Tier I capital (to average assets), actual, amount Banking Regulation, Tier 1 Leverage Capital, Actual Cash dividends Dividends, Common Stock, Cash Assets Assets [Abstract] Due after 10 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Total Liabilities, Fair Value Disclosure 2026 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Deferred tax assets: Deferred Tax Assets, Net [Abstract] Other Deferred Tax Assets, Other Common equity tier I capital (to risk-weighted assets), capital requirements, amount Common Equity Tier I Capital (to risk-weighted assets), capital requirements amount The minimum amount of Common Equity Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action. Liabilities: Liabilities [Abstract] Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Interest-bearing demand deposits Demand Deposit Accounts Treasury securities US Treasury Securities [Member] Cash paid for income taxes Income Taxes Paid, Net Available-for-sale, securities in unrealized loss positions, greater than one year, percentage Available-For-Sale, Securities In Unrealized Loss Positions, Greater Than 12 Months, Percentage Of Total Securities Available-For-Sale, Securities In Unrealized Loss Positions, Greater Than 12 Months, Percentage Of Total Securities Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Retirement Plan Type [Axis] Retirement Plan Type [Axis] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Interest income Interest and Dividend Income, Including Tax Equivalent Adjustment, Operating Interest and Dividend Income, Including Tax Equivalent Adjustment, Operating Retained Earnings Retained Earnings [Member] Credit Exposure Of Loan Portfolio [Axis] Credit Exposure Of Loan Portfolio [Axis] Credit exposure Of Loan Portfolio [Domain] Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price Net amortization of premium/discount on investment securities Accretion (Amortization) of Discounts and Premiums, Investments Occupancy Occupancy, Net Total liabilities and shareholders’ equity Liabilities and Equity Processing Fees Processing Fees [Policy Text Block] The accounting policy for processing fees. Operating lease, right-of-use asset Operating Lease, Right-of-Use Asset Basic Earnings Per Share (in dollars per share) Earnings Per Share, Basic Cash and due from banks Cash and Due from Banks Accounting Policies [Abstract] Accounting Policies [Abstract] Issuance of common stock: Shares Granted or Issued, Share-Based Payment Arrangement [Abstract] Net deferred tax assets Deferred Tax Assets, Net Fair value, January 1 Fair value, December 31 Total plan assets Defined Benefit Plan, Plan Assets, Amount Percentage holding required to account investments under non-marketable equity investments Percentage holding required to account investments under non-marketable equity investments The percentage holding required to account investments under non-marketable equity investments. Loans Subject To Normal Monitoring Loans Subject To Normal Monitoring [Member] Loans Subject To Normal Monitoring [Member] Weighted average discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Entity Address, City or Town Entity Address, City or Town Net increase in accounts and drafts payable Increase (Decrease) in Accounts Payable and Other Operating Liabilities Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Time Deposits, Fiscal Year Maturity [Abstract] Time Deposits, Fiscal Year Maturity [Abstract] Federal tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Accounting Policies [Table] Accounting Policies [Table] Accounting Policies Tier I capital (to risk-weighted assets), requirement to be well-capitalized, amount Banking Regulation, Tier 1 Risk-Based Capital, Well Capitalized, Minimum Document Transition Report Document Transition Report Increase (decrease) in pension liability Increase (Decrease) in Obligation, Pension Benefits Dividends from Subsidiaries and Equity in Undistributed Subsidiary Income Dividends from Subsidiaries and Equity in Undistributed Subsidiary Income Dividends from Subsidiaries and Equity in Undistributed Subsidiary Income Common stock, shares authorized (in shares) Common Stock, Shares Authorized Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Total capital (to risk weighted assets), requirement to be well-capitalized, amount Banking Regulation, Total Risk-Based Capital, Well Capitalized, Minimum Federal Home Loan Bank Federal Home Loan Bank [Member] Federal Home Loan Bank [Member] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] Entity Public Float Entity Public Float Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Financing Receivable, Excluding Accrued Interest, Modified, after 12 Months Financing Receivable, Excluding Accrued Interest, Modified, after 12 Months Financing Receivable, Excluding Accrued Interest, Modified, after 12 Months Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Exercised Gross Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Other Operating Expense Other Operating Income and Expense [Text Block] Summary of Operations Summary of Operations [Policy Text Block] Summary of Operations. Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Other Bank Service Fees and Other Revenue Not From Contract With Customer Bank Service Fees and Other Revenue Not From Contract With Customer Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Measurement Input, Long Term Rate Of Return Measurement Input, Long Term Rate Of Return [Member] Measurement Input, Long Term Rate Of Return Non-U.S. Equity Securities Non-U.S. Equity Securities [Member] Foreign Equity Securities [Member]. Measurement Input Type [Axis] Measurement Input Type [Axis] Contractual Interest Rate Reduction Contractual Interest Rate Reduction [Member] Due in 1 year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Interest on short-term borrowings Interest Expense, Short-Term Borrowings Common stock, par value $0.50 per share; 40,000,000 shares authorized; 15,505,772 shares issued at December 31, 2023 and 2022; 13,582,375 and 13,669,656 shares outstanding at December 31, 2023 and 2022, respectively. Common Stock, Value, Outstanding Commercial letters of credit Commercial letters of credit [Member] Commercial letters of credit member. Fair value of shares vested Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Commercial and industrial Commercial and Industrial [Member] Commercial And Industrial Loan Due after 5 years through 10 years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Loans, net Loans Receivable, Fair Value Disclosure Right of use asset Deferred Tax Liabilities, Leasing Arrangements Deferred income tax benefit Deferred Income Tax Expense (Benefit) Loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Accounts and drafts payable Accounts Payable, Fair Value Disclosure Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Income Taxes Income Tax, Policy [Policy Text Block] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] Aggregate intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding Forfeitures (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Weighted average interest rate Weighted average interest rate The weighted average interest rate of interest bearing deposits. Non-marketable Equity Investments Equity Method Investments [Policy Text Block] Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Schedule of Intangible Assets and Goodwill Schedule of Intangible Assets and Goodwill [Table Text Block] Participating Mortgage Loans [Line Items] Participating Mortgage Loans [Line Items] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Financial Fees Financial Fees [Policy Text Block] Financial Fees Other assets Other Assets Directors’ stock grants Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Entity Registrant Name Entity Registrant Name Net change in other assets Increase (Decrease) in Other Operating Assets Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Auditor Name Auditor Name Document Period End Date Document Period End Date Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Summary of the Fair Value Measurements by Type of Asset Summary of the Fair Value Measurements by Type of Asset [Table Text Block] Tabular disclosure for fair value of plan assets by type of asset. Treasury Stock Treasury Stock, Common [Member] Entity Central Index Key Entity Central Index Key Line of Credit Facility, Fair Value of Amount Outstanding Line of Credit Facility, Fair Value of Amount Outstanding Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Purchase of bank-owned life insurance Payment to Acquire Life Insurance Policy, Investing Activities Real Estate, Commercial, Mortgage Real Estate Commercial Mortgage [Member] Real Estate Commercial Mortgage Net increase in accounts and drafts payable Increase (Decrease) In Accounts and Drafts Payable Net change during the reporting period in the carrying amount of accounts and drafts payable. Gross Carrying Amount Finite-Lived Intangible Assets, Gross Income tax expense Total income tax expense Income Tax Expense (Benefit) Average remaining contractual terms Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Disclosures about Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Schedule of Credit Exposure of the Loan Portfolio Schedule of Credit Exposure of the Loan Portfolio [Table Text Block] Tabular disclosure for credit exposure of loan portfolio by internally assigned credit grade. Other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent (Release of) provision for credit losses (Release of) provision for credit losses Financing Receivable, Credit Loss, Expense (Reversal) Schedule Of Net Periodic Pension Cost Related To SERP Schedule Of Net Periodic Pension Cost Related To SERP [Table Text Block] Schedule Of Net Periodic Pension Cost Related To SERP Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Audit Information [Abstract] Audit Information [Abstract] Lender Name [Axis] Lender Name [Axis] AFS, 12 months or more, Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Noncontributory Profit Sharing Program Noncontributory Profit Sharing Program [Member] Noncontributory Profit Sharing Program [Member] Operating lease, weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Unrealized loss on investment securities available-for-sale (1) Deferred Tax Asset, Debt Securities, Available-for-Sale, Unrealized Loss U.S. Core U.S. Core Opportunistic [Member] United States Core Opportunistic [Member]. 60-89 Days Financial Asset, 60 to 89 Days Past Due [Member] Fee revenues Fee revenues Revenue from Contract with Customer, Excluding Assessed Tax Entity [Domain] Entity [Domain] Payment Deferral Payment Deferral [Member] Interest on deposits Total Interest Expense, Deposits Amendment Flag Amendment Flag Legal Entity [Axis] Legal Entity [Axis] Net actuarial loss in accumulated other comprehensive loss Defined Benefit Plan, Amortization of Gain (Loss) Reclassification adjustments for losses (gains) included in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year Cash and Cash Equivalents, at Carrying Value AFS, Less than 12 Months, Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Shares exercised, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Exercised Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Exercised Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Net interest income Intersegment income (expense) Interest Income (Expense), Net Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Expected long-term rate of return on assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets Due in 1 year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Credit Facility [Domain] Credit Facility [Domain] Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Non- accrual Financing Receivable, Excluding Accrued Interest, Nonaccrual Premises, useful life Property, Plant and Equipment, Useful Life Exercised (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercises in Period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercises in Period, Weighted Average Exercise Price $100 to less than $250 Interest Expense Time Deposits 100000 or More and Less Than 250000 Interest expense incurred on time deposits, including certificates of deposits, $100,000 or more and less than $250,000 in domestic offices. Credit Exposure Of Loan Portfolio [Domain] Credit Exposure Of Loan Portfolio Domain [Domain] Credit Exposure Of Loan Portfolio Domain Leasehold Improvements Leasehold Improvements [Member] Total deferred tax liabilities Deferred Tax Liabilities, Net Actual investment return Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Weighted average discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Deposits Deposits, Fair Value Disclosure Weighted average common shares outstanding assuming dilution (in shares) Weighted Average Number of Shares Outstanding, Diluted Amortization expense, rolling year four Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Four Total interest income Interest and Dividend Income, Operating Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Available-for-sale securities, gross realized losses Debt Securities, Available-for-Sale, Realized Loss Purchases of premises and equipment, net Payments to Acquire Property, Plant, and Equipment Interest-bearing demand deposits Interest Expense, Demand Deposit Accounts Additional paid-in capital Additional Paid in Capital, Common Stock Additional Paid-in Capital Additional Paid-in Capital [Member] Net (increase) decrease in accounts and drafts receivable from customers Net (Increase) Decrease In Accounts And Drafts Receivable From Customers Net (Increase) Decrease In Accounts And Drafts Receivable From Customers Document Annual Report Document Annual Report Employee restricted stock units vested Stock Issued During Period, Shares, Conversion of Units 30-59 Days Financial Asset, 30 to 59 Days Past Due [Member] 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Total assets Total assets Assets Equity in undistributed income of subsidiaries Equity in undistributed income of subsidiaries Income (Loss) from Equity Method Investments Real Estate, Commercial, Construction Real Estate Commercial Construction [Member] Real Estate Commercial Construction Loan Summary of Projected Benefit Obligation Summary of Projected Benefit Obligation [Table Text Block] Tabular disclosure for projected benefit obligation, assets, funded status and amounts recognized. Cover [Abstract] Income from subsidiaries – management fees Investment Income, Nonoperating Subsequent Events Subsequent Events [Text Block] Loans Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Personnel Salaries and employee benefits Labor and Related Expense Financial fees Financial Fees [Member] Financial Fees Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Total undiscounted cash flows Lessee, Operating Lease, Liability, to be Paid Short-term investments Short-Term Investments Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Pension Plan The Plan Pension Plan [Member] Schedule of Pretax Amounts in Accumulated Other Comprehensive Loss Schedule of Pretax Amounts in Accumulated Other Comprehensive Loss [Table Text Block] Tabular disclosure for pre-tax amounts in accumulated other comprehensive loss. Industry Segment Information Segment Reporting Disclosure [Text Block] Revenue, Performance Obligation [Abstract] Revenue, Performance Obligation [Abstract] Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Income before income tax expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Cash Flows From Financing Activities: Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Plan assets, target allocation percentage % of Total Portfolio Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Equity Component [Domain] Equity Component [Domain] Investments in bank-owned life insurance Bank Owned Life Insurance Schedule of Assumptions used to Determine Net Pension Cost Schedule of Assumptions used to Determine Net Pension Cost [Table Text Block] Tabular disclosure for Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost. Other Deferred Tax Liabilities, Other Scenario [Axis] Scenario [Axis] Weighted average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Entity Current Reporting Status Entity Current Reporting Status Premises and equipment Deferred Tax Liabilities, Property, Plant and Equipment Common equity tier I capital (to risk-weighted assets), actual, amount Banking Regulation, Tier 1 Risk-Based Capital, Actual Amortization expense, rolling year three Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Three Property, Plant and Equipment, Other Types Property, Plant and Equipment, Other Types [Member] Pension Plan, Service After Year Seven Pension Plan, Service After Year Seven [Member] Pension Plan, Service After Year Seven Fee Revenue and Other Income: Revenues [Abstract] Cash Cash and Cash Equivalents [Member] Consolidated Entities [Domain] Consolidated Entities [Domain] $250 or more (1) Time Deposits, More than $250,000 The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more. Provision for (release of) credit losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Tier I capital (to average assets), actual, ratio Tier I capital (to average assets), actual ratio Tier 1 Leverage Capital divided by average assets as defined in the regulations. Five years Time Deposit Maturities, Year Five Comprehensive Income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Three years Time Deposit Maturities, Year Three Less than $100 Interest Expense, Time Deposits, Less than $100,000 Schedule of Assumptions used to Determine Projected Benefit Obligation Schedule of Assumptions used to Determine Projected Benefit Obligation [Table Text Block] Tabular disclosure for assumptions used calculating benefit obligation. Uninsured scheduled maturities, year one through three Time Deposit Liability Uninsured, Maturity, Year One Through Three Time Deposit Liability Uninsured, Maturity, Year One Through Three Segments [Axis] Segments [Axis] Statement [Line Items] Statement [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Unrecognized tax benefit, interest on income taxes accrued Unrecognized Tax Benefits, Interest on Income Taxes Accrued Premises and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Decrease (increase) in payments in advance of funding Net decrease (increase) in payments in advance of funding (Increase) Decrease In Payments In Excess Of Funding Net change during the reporting period in the carrying amount of payments in excess of funding. After Year Seven SERP, Service After Year Seven [Member] SERP, Service After Year Seven Scenario [Domain] Scenario [Domain] Investment in Debt Securities Investment in Debt Securities [Policy Text Block] Disclosure of accounting policy for investments in debt securities. Schedule of Debt Schedule of Debt [Table Text Block] Long-term line of credit Long-Term Line of Credit Schedule of Investment Securities Debt Securities, Available-for-Sale [Table Text Block] Total capital (to risk-weighted assets), actual, ratio Total capital (to risk-weighted assets), actual ratio Total Capital divided by risk weighted assets as defined in the regulations. Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Individually Evaluated Loans Impairment of Loans [Policy Text Block] Disclosure of accounting policy for impairment of loans.