ESPP Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan Schedule of Short-term Borrowings Schedule of Short-Term Debt [Table Text Block] Decrease in interest income on swap transactions Interest Income, Interest-Earning Asset, Increase (Decrease) Award Timing Predetermined Award Timing Predetermined [Flag] Fair value of financial assets acquired Fair value of PCD financial assets Business Combination, Recognized Asset Acquired, Financial Asset Amortization of investments in tax-advantaged projects Investment Program, Proportional Amortization Method, Applied, Amortization Expense Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Issuance of treasury stock for the ESPP Proceeds from Issuance of Treasury Stock for Employee Stock Purchase Program The cash inflow from the issuance of an equity stock for employee stock purchase program that has been previously reacquired by the entity. Income tax credits and other tax benefits Investment Program, Proportional Amortization Method, Elected, Income Tax Credit Tabular List, Table Tabular List [Table Text Block] Interest-bearing transaction deposits Interest Bearing Transaction Deposits The aggregate amount of all domestic and foreign interest-bearing transaction deposits liabilities held by the entity. Impact of Recently Adopted Accounting Standards and Recently Issued Accounting Standards Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Finance lease costs: Finance Lease, Liability [Abstract] Schedule of Estimated Fair Values of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Position [Axis] Position [Axis] Measurement Basis [Axis] Measurement Basis [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] 12 months or more Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Amortization of unrecognized losses on securities transferred to held to maturity OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Debt securities held to maturity Debt Securities, Held-to-Maturity, Maturity [Abstract] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Consideration paid Business Combination, Consideration Transferred [Abstract] Stock, Class of Stock [Table] Stock, Class of Stock [Table] Busey Awards Busey Awards [Member] Busey Awards Due after ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost Minimum Capital Requirement Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Due after one year through five years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year One through Five Watch Watch Represents the grade which includes loans on management's watch list and that is intended to be utilized on a temporary basis for a pass grade borrower where a significant risk-modifying action is anticipated in the near future. Adjustment to Compensation, Amount Adjustment to Compensation Amount (Increase) decrease in other assets Increase (Decrease) in Other Operating Assets Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Payment Deferral And Extended Maturity Payment Deferral And Extended Maturity [Member] Payment Deferral And Extended Maturity Dividend equivalents on RSUs/PSUs/DSUs Stock Issued During Period, Value, Dividend Equivalent Stock Issued During Period, Value, Dividend Equivalent Notional Amount Derivative Asset, Notional Amount Employee Stock Option Share-Based Payment Arrangement, Option [Member] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Realized net gains (losses) on securities Debt and Equity Securities, Realized Gain (Loss) Cash dividends on common stock Dividends, Common Stock, Cash Total stockholders’ equity Beginning balance Ending balance Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Insider Trading Policies and Procedures [Line Items] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Bank property held for sale with impairment Bank property held for sale with impairment Bank Property Held for Sale, Fair Value Disclosure The fair value of bank property held for sale. Nature of Operations Nature of Operations [Policy Text Block] Disclosure of accounting policy for nature of operations. Financial assets Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Fair Value, Recurring Fair Value, Recurring [Member] Fair Value Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value Minimum To Be Well Capitalized Banking Regulation, Tier 1 Leverage Capital, Well Capitalized, Minimum Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Gross aggregate fair value of swap assets Cash Flow Hedge Derivative Instrument Assets at Fair Value State and Local Jurisdiction State and Local Jurisdiction [Member] Minimum To Be Well Capitalized Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Well Capitalized, Minimum Deposits Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Deposits Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Deposits Cover [Abstract] Cover [Abstract] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Maximum Maximum [Member] OREO and other repossessed assets acquired in settlement of loans Real Estate Owned, Transfer to Real Estate Owned Debt securities held to maturity Amortized Cost Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Useful life Finite-Lived Intangible Asset, Useful Life Total Debt securities with gross unrealized or unrecognized losses, fair value Debt Securities, Available-for-Sale, Unrealized Loss Position Minimum To Be Well Capitalized Banking Regulation, Tier 1 Risk-Based Capital, Well Capitalized, Minimum Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Unfunded investment obligations Investment-related Liabilities Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Exercisable at end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non Options, Exercisable, Number Share-Based Compensation Arrangement by Share-Based Payment Award, Non Options, Exercisable, Number Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Debt securities available for sale, sold Debt Securities, Available-for-Sale, Sold at Par Value Measurement Input, Comparability Adjustment Measurement Input, Comparability Adjustment [Member] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Other assets Other Assets [Member] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Weighted Average Term Extension Financing Receivable, Modified, Weighted Average Term Increase from Modification Income (loss) before income taxes Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Actual Banking Regulation, Tier 1 Leverage Capital Ratio, Actual Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from disposition of premises and equipment Proceeds from Sale of Property, Plant, and Equipment Amortization of mortgage servicing rights Amortization of Mortgage Servicing Rights (MSRs) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Total interest expense Interest expense Interest Expense, Operating Assumed in business combinations Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Assumed In Acquisition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Assumed In Acquisition Interest expense Finance Lease, Interest Expense Document Fiscal Period Focus Document Fiscal Period Focus Award Timing Method Award Timing Method [Text Block] Non-accrual Financing Receivable, Excluding Accrued Interest, Nonaccrual Award Type [Axis] Award Type [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Schedule of Business Acquisition, Pro Forma Information Business Combination, Pro Forma Information [Table Text Block] Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol 2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Non-taxable interest income Interest Income, Securities, Operating, Tax Exempt Forward Starting SOFR Loan Swap 6 Month Forward Starting SOFR Loan Swap [Member] 6 Month Forward Starting SOFR Loan Swap Business Combination, Contingent Consideration [Table] Business Combination, Contingent Consideration [Table] Entity Address, City or Town Entity Address, City or Town Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Finance leases Finance Lease, Weighted Average Discount Rate, Percent FirsTech FirsTech This member stands for FirsTech. Restricted bank stock Federal Home Loan Bank Stock and Federal Reserve Bank Stock Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount RSU Awards Restricted Stock Units (RSUs) [Member] Income Statement Location [Domain] Statement of Income Location, Balance [Domain] ACL recorded for estimated uncollectible contractual cash flows specific to PCD financial assets Business Combination, Acquired Receivable, Purchased without Credit Deterioration, Contractual Cash Flow, Estimated Uncollectible Aggregate amount of time deposits with a minimum denomination that meets or exceeds the FDIC insurance limit of $250,000 Time Deposits, at or Above FDIC Insurance Limit Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Total consideration paid Business Combination, Consideration Transferred Entity Emerging Growth Company Entity Emerging Growth Company Actual Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Actual Net issuance of treasury stock for stock-based compensation plans (in shares) Stock Issued During Period, Shares, Stock Based Compensation Plans, Net Stock Issued During Period, Shares, Stock Based Compensation Plans, Net Net occupancy expense of premises Occupancy Net [Member] Occupancy Net Finance leases Finance Lease, Weighted Average Remaining Lease Term Cash pledged to secure obligations Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Outstanding at beginning of year (in shares) Outstanding at end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Noninterest income Revenue from Contract with Customer, Including Assessed Tax Unamortized debt issuance costs Debt Issuance Costs, Net Unrealized gains (losses) on cash flow hedges, net of tax Net change in fair value of interest rate swaps Net gains (losses) on mortgage banking derivatives Derivative, Gain (Loss) on Derivative, Net Restricted cash and cash equivalents Restricted Cash and Cash Equivalent Total noninterest income Noninterest Income Less: Amounts representing interest Finance Lease, Liability, Undiscounted Excess Amount Common stock outstanding (in shares) Common Stock, Shares, Outstanding Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock, $0.001 par value Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock, $0.001 par value [Member] Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock, $0.001 par value Remainder of 2026 Lessor, Operating Lease, Payment to be Received, Remainder of Fiscal Year Unrecognized gross losses Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss Noninterest expense Noninterest Expense [Abstract] Purchases of interest-bearing time deposits in other banks Purchases of Interest Bearing Time Deposits In Other Banks Purchases of Interest Bearing Time Deposits In Other Banks Cash and due from banks Cash and Due from Banks Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Customer assets held in trust Customer Assets Held in Trust Assets under care held for customers, that are not included in the Company's consolidated financial statements. Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Due after one year through five years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Pledged Status [Domain] Pledged Status [Domain] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income taxes Income Tax Expense (Benefit) Floating interest rate margin (as a percent) Debt Instrument, Basis Spread on Variable Rate Tax effect Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Other assets Other Assets Beginning Balance Ending Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Document Information [Line Items] Document Information [Line Items] Thereafter Time Deposit Maturities, after Year Five Preferred shares issued (in shares) Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Hedging Relationship [Axis] Hedging Relationship [Axis] Net change in unrealized gains (losses) on cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Due in one year or less Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Total Available for Sale and Held to Maturity, Debt Securities in Unrealized Loss Position [Abstract] N/A Proceeds from the redemption of restricted bank stock Proceeds From Redemption Of Federal Home Loan Bank And Federal Reserve Bank Stock Proceeds From Redemption Of Federal Home Loan Bank And Federal Reserve Bank Stock Wealth management fees Asset Management [Member] Balances carried in AOCI Balances carried in AOCI [Abstract] na Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Tier 1 Capital to Risk Weighted Assets, Amount Banking Regulation, Tier 1 Risk-Based Capital [Abstract] Losses reclassified from OCI to interest income, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification to Interest Income, before Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification to Interest Income, after Tax Net cash received in (paid for) acquisitions (see Note 2) Payments to Acquire Businesses, Net of Cash Acquired All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Dividends on preferred stock Dividends on preferred stock Preferred Stock Dividends, Income Statement Impact Other service charges on deposit accounts Other Service Charges On Deposit Accounts [Member] Other Service Charges On Deposit Accounts Other noninterest income Noninterest Income, Other Operating Income Non-vested at beginning of period (in shares) Non-vested at end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Repayment of short-term borrowings Repayments of Short-Term Debt Unrealized (gains) losses recognized on equity securities, net Increase (Decrease) in Equity Securities, FV-NI Total commitments Fair Value Disclosure, off-Balance-Sheet Risks, Face Amount, Liability Proceeds from sales of debt securities available for sale Proceeds from Sale of Debt Securities, Available-for-Sale Debt securities available for sale Fair Value Fair Value Debt Securities, Available-for-Sale, Excluding Accrued Interest Proceeds from maturities of interest-bearing time deposits in other banks Proceeds From Maturities Of Interest Bearing Time Deposits In Other Banks Proceeds From Maturities Of Interest Bearing Time Deposits In Other Banks Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Subsequent Event Subsequent Event [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Net interest income Net interest income Interest Income (Expense), Operating Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Actual Banking Regulation, Tier 1 Risk-Based Capital, Actual Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Transfer of loans held for sale to portfolio loans Loan, Transfer from Held-for-Sale to Held-in-Portfolio 2030 Finance Lease, Liability, to be Paid, Year Four Assets acquired Business Combination, Recognized Asset Acquired, Asset [Abstract] Debt, weighted average maturity period Debt, weighted average maturity period Debt, Weighted Average Maturity Period Debt, Weighted Average Maturity Period Equity Components [Axis] Equity Components [Axis] 2023 2022 Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Standby letters of credit Standby Letters of Credit [Member] Payment technology solutions Technology Service [Member] Schedule of Contractual Amount of Exposure to Off-Balance-Sheet Risk Schedule Of Contractual Amount Of Exposure To Off Balance Sheet Risk [Table Text Block] Tabular disclosure of contractual amount of exposure to off-balance-sheet risk, wherein exposure to credit loss is represented by the contractual amount of those commitments. Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Expired (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Expirations in Period Entity Address, State or Province Entity Address, State or Province Financing cash flows from finance leases Finance Lease, Principal Payments Substandard Substandard [Member] Total interest income Interest and Dividend Income, Operating Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Special Mention Special Mention [Member] Lease liabilities: Lease Liabilities [Abstract] Lease Liabilities Risk participation agreements sold Risk Participation Agreement Sold [Member] Risk Participation Agreement Sold Individual: Individual [Axis] Rents to be received Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Abstract] Income Tax Jurisdiction [Domain] Income Tax Jurisdiction [Domain] Interchange expense Interchange Expense Amount of interchange expenses incurred during the period. Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Minimum Capital Requirement Banking Regulation, Tier 1 Risk-Based Capital, Capital Adequacy, Minimum Entity Interactive Data Current Entity Interactive Data Current Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Loans identified as impaired Financing Receivable, Modified [Line Items] Interest income Interest and Dividend Income, Operating [Abstract] Total noninterest expense Noninterest Expense Schedule of Shares Remaining Available for Issuance Under Busey’s Equity Compensation Plans Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] Payment Deferral Payment Deferral [Member] Count of debt securities Total Count Of Debt Securities, Available For Sale Securities Total count of available for sale debt securities. Deposits Interest Expense, Deposits Noninterest income Noninterest Income [Abstract] Unfunded investment obligations Unfunded investments Represents unfunded investments. Other liabilities Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Other Liabilities Amount of other liabilities assumed at the acquisition date. 2028 Finance Lease, Liability, to be Paid, Year Two Net of accumulated amortization Finance Lease, Right-of-Use Asset, Accumulated Amortization Schedule of Future Minimum Lease Payments Lessor, Operating Lease, Payment to be Received, Maturity [Table Text Block] (Gain) loss on life insurance proceeds Gain Loss on Life Insurance Proceeds Amount of gain (loss) recognized in settlement of life insurance. Noninterest expense Non-interest expense Primary financial statement caption encompassing noninterest expense. Shares received for each share owned (in shares) Business Combination, Shares Received For Each Share Owned Business Combination, Shares Received For Each Share Owned Net decrease in federal funds purchased and securities sold under agreements to repurchase Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net Schedule of Unamortized Stock-Based Compensation Expense Share-Based Payment Arrangement, Nonvested Award, Cost [Table Text Block] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Revenue Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Mortgage loans originated for sale Payment for Origination, Loan, Mortgage, Held-for-Sale Deferred Income Taxes and Other Assets [Abstract] Deferred Income Taxes and Other Assets [Abstract] Minimum Capital Requirement Banking Regulation, Tier 1 Leverage Capital, Capital Adequacy, Minimum Noninterest-bearing Noninterest-bearing demand deposits Noninterest-Bearing Deposit Liabilities Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Fair Values of Derivative Assets and Liabilities Recorded in Consolidated Balance Sheet Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Total, gross write-offs Financing Receivable, Excluding Accrued Interest, Before Allowance for Credit Loss, Writeoff Financing Receivable, Excluding Accrued Interest, Before Allowance for Credit Loss, Writeoff Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Minimum Capital Requirement Banking Regulation, Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Class of Stock [Domain] Class of Stock [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Customer contracts Long [Member] Common Equity Tier 1 Capital to Risk Weighted Assets, Ratio Common Equity Risk Based Ratios [Abstract] No definition available. Unrecognized Gains (Losses) on Debt Securities Held to Maturity AOCI, Accumulated Gain (Loss), Debt Securities, Held-To-Maturity, Parent [Member] AOCI, Accumulated Gain (Loss), Debt Securities, Held-To-Maturity, Parent Short-term borrowings, mature period Federal Funds Maturity Period Period of time between issuance and maturity of federal funds, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. OREO and other repossessed assets with subsequent impairment Real Estate Acquired Through Foreclosure Balance Sheet Location [Axis] Statement of Financial Position Location, Balance [Axis] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Number of states in which entity operates Number of States in which Entity Operates Entity Address, Address Line One Entity Address, Address Line One Income tax examination, number of lawsuits filed Income Tax Examination, Number Of Lawsuits Filed Income Tax Examination, Number Of Lawsuits Filed AOCI Total AOCI Attributable to Parent [Member] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] DERIVATIVE FINANCIAL INSTRUMENTS Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Stock Issuances Schedule of Stock by Class [Table Text Block] Other liabilities Other Liabilities [Member] Fair Value as of Grant Date Award Grant Date Fair Value Realized gains and losses on debt securities Debt Securities, Available-for-Sale, Realized Gain (Loss) [Abstract] 2022 2021 Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Schedule of Long-term Borrowings Schedule of Long-Term Debt Instruments [Table Text Block] Salaries, wages, and employee benefits Labor and Related Expense Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Minimum Capital Requirement Banking Regulation, Tier 1 Leverage Capital Ratio, Capital Adequacy, Minimum Unamortized stock-based compensation Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Document Quarterly Report Document Quarterly Report Less than 12 months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Loans evaluated individually, net of related allowance Financing Receivable, Measurement Input Financing Receivable, Measurement Input Actual Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual Bank Overdrafts Bank Overdrafts [Member] DEPOSITS Deposit Liabilities Disclosures [Text Block] Income on bank owned life insurance Bank Owned Life Insurance Income Long-term borrowings Long-Term Debt, Fair Value Schedule of Quantitative Information About Level 3 Fair Value Measurements Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] 12 months or more Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Counterparty Name [Domain] Counterparty Name [Domain] 2028 Lessee, Operating Lease, Liability, to be Paid, Year Two Investments, All Other Investments [Abstract] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Available for Sale Available for Sale, Debt Securities in Unrealized Loss Position [Abstract] N/A Impairment of fixed assets held for sale Impairment of Long-Lived Assets to be Disposed of DSU Awards Deferred Stock Units [Member] Deferred Stock Units Non-PEO NEO Non-PEO NEO [Member] Other Corporate Reconciling Items And Eliminations [Member] Corporate Reconciling Items And Eliminations Position [Domain] Position [Domain] Preferred stock, dividend rate Preferred Stock, Dividend Rate, Percentage Other interest income Interest Income, Other Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Notional Amount Derivative Liability, Notional Amount Brokered savings deposits and money market deposits Brokered Saving Deposits And Money Market Deposits Represents the amount of brokered saving deposits and money market deposits. Unrealized gross gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Award Type [Domain] Award Type [Domain] 2027 Lessee, Operating Lease, Liability, to be Paid, Year One Net unrealized holding gains (losses) on cash flow hedges Net gains (losses) recognized in OCI, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Compensation Amount Outstanding Recovery Compensation Amount Minimum To Be Well Capitalized Banking Regulation, Total Risk-Based Capital, Well Capitalized, Minimum Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Number of full-service locations Number Of Full-Service Locations Which Entity Operates Number Of Full-Service Locations Which Entity Operates MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] FHLB Assets Pledged As Collateral, Federal Home Loan Bank [Member] Assets Pledged As Collateral, Federal Home Loan Bank Weighted average number of common shares outstanding Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Reclassification adjustment for realized (gains) losses on debt securities available for sale included in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Loans purchased Financing Receivable, Purchase 2030 Time Deposit Maturities, Year Four Remainder of 2026 Finance Lease, Liability, to be Paid, Remainder of Fiscal Year Weighted average discount rates: Weighted Average Discount Rate [Abstract] Weighted Average Discount Rate Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Schedule of Financial Instruments Owned and Pledged as Collateral Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block] Total long-term borrowings Long-Term Debt and Lease Obligation AOCI Accumulated Other Comprehensive Income (Loss), Net of Tax Financial Instruments [Domain] Financial Instruments [Domain] Net change in unrealized/unrecognized gains (losses) on debt securities OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Due after ten years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 PSU Awards Performance Shares [Member] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Pledging Purpose [Domain] Pledging Purpose [Domain] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Banking Regulation, Regulatory Capital Requirement, Compliance [Table] Minimum Minimum [Member] Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Accounts, Notes, Loans and Financing Receivable [Line Items] Distributions of portfolio loans Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Debt securities available for sale sold, tax benefit Debt Securities, Available-For-Sale, Sold At Par Value, Tax Expense (Benefit) Debt Securities, Available-For-Sale, Sold At Par Value, Tax Expense (Benefit) Fair Value Measurement [Domain] Fair Value Measurement [Domain] Net income Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax Minimum Capital Requirement Banking Regulation, Total Risk-Based Capital, Capital Adequacy, Minimum BORROWINGS Debt Disclosure [Text Block] (Gain) loss on sales of debt securities, net Gain (Loss) on Sale of Investments Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Operating cash flows from operating leases Operating Lease, Payments Loans evaluated individually, net of related allowance Financing Receivable, Individually Evaluated for Credit Loss, Average Recorded Investment Financing Receivable, Individually Evaluated for Credit Loss, Average Recorded Investment SSARs Stock Appreciation Rights (SARs) [Member] 90+ days past due and still accruing Financing Receivable, 90 Days or More Past Due, Still Accruing OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES Commitments and Contingencies Disclosure [Text Block] Interest rate swaps: receive-fixed, pay-floating Interest rate swaps - pay floating, receive fixed Represent Interest rate swaps, pay floating, receive fixed. Secured borrowings Secured Borrowings [Member] Secured Borrowings Gross aggregate fair value of the swaps Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract] Weighted average number of common shares outstanding, diluted (in shares) Weighted average number of common shares outstanding, diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] Proceeds from life insurance Proceeds from Life Insurance Policy Entity Small Business Entity Small Business Common stock issuance costs Payments of Stock Issuance Costs Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity [Abstract] Weighted average maturity Derivative, Average Remaining Maturity Preferred shares outstanding (in shares) Preferred Stock, Shares Outstanding SOFR Loan Swaps SOFR Loan Swap [Member] SOFR Loan Swap Document Transition Report Document Transition Report Total undiscounted cash flows Finance Lease, Liability, to be Paid Preferred stock, value, outstanding Preferred Stock, Value, Outstanding Underlying Securities Award Underlying Securities Amount Schedule of Securities Sold Under Agreements to Repurchase Schedule of Securities Financing Transactions and Short-term Debt [Table Text Block] Tabular disclosure of distributions of securities sold under agreements to repurchase and short-term borrowings and related weighted average interest rates. Aggregate amount of time deposits with a minimum denomination of $100,000 Time Deposits, $100,000 or More Gross gains on debt securities Debt Securities, Available-for-Sale, Realized Gain Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Net amortization (accretion) of premium (discount) on time deposits Accretion of Premiums and Discounts on Time Deposits Represents the accretion of premiums and discounts on time deposits. Subsequent Events Subsequent Events, Policy [Policy Text Block] Weighted average remaining lease terms: Weighted Average Remaining Lease Terms [Abstract] Weighted Average Remaining Lease Terms Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Short-term lease costs Short-Term Lease, Cost Saving deposits and money market deposits Deposits, Interest-bearing Transaction Deposits, Saving Deposits and Money Market Deposits The aggregate of saving and money market deposit liabilities held by the entity. Fair Value Debt Securities, Held-To-Maturity, Unrealized Loss Position, Fair Value [Abstract] Debt Securities, Held-To-Maturity, Unrealized Loss Position, Fair Value Long-term borrowings Other Long Term Debt [Member] Other Long Term Debt Document Type Document Type Level 3 Inputs Fair Value, Inputs, Level 3 [Member] Outstanding at beginning of year (in shares) Outstanding at end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Number EARNINGS PER COMMON SHARE Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Additional paid-in capital Additional Paid in Capital Product and Service [Axis] Product and Service [Axis] Revolving Loans, charge-off Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Variable lease costs Variable Lease, Cost Amount of interest collected and recognized on a cash basis Financing Receivable, Nonaccrual And Equal To Or Greater Than 90 Days Past Due, Cash Basis Interest Income Financing Receivable, Nonaccrual And Equal To Or Greater Than 90 Days Past Due, Cash Basis Interest Income Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses Held For Maturity Securities in Unrealized Loss Positions as Percentage of Aggregate Carrying Value Represents the total number of securities in the investment portfolio which are in an unrealized loss position as a percentage of the aggregate carrying value. Wealth Management Wealth Management Represents information pertaining to Wealth management segment. Statistical Measurement [Axis] Statistical Measurement [Axis] 2025, charge-off 2024, charge-off Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Cash paid for withholding taxes on stock-based payments Payment, Tax Withholding, Share-Based Payment Arrangement Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Leverage Ratio of Tier 1 Capital to Average Assets, Ratio Banking Regulation, Leverage Ratio [Abstract] Due after one year through five years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Net income (loss) available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Replacement awards Replacement Awards [Member] Replacement Awards OCI OCI, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Schedule of Net Gains (Losses) Relating to these Derivative Instruments Derivative Instruments, Gain (Loss) [Table Text Block] Current Financing Receivable, Excluding Accrued Interest, Modified, after 12 Months Level 1 Inputs Fair Value, Inputs, Level 1 [Member] PCD Financial Assets Purchased with Credit Deterioration, Financial Assets [Abstract] Purchased with Credit Deterioration, Financial Assets Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding Interest-bearing time deposits in other banks Interest Bearing Time Deposits In Other Banks Interest Bearing Time Deposits In Other Banks Preferred stock redemption price per share (in dollars per share) Preferred Stock, Redemption Price Per Share Diluted earnings (loss) per common share (in dollars per share) Diluted earnings (loss) per common share (in dollars per share) Earnings Per Share, Diluted FDIC insurance Federal Deposit Insurance Corporation Premium Expense Schedule of Lease-Related Balances Schedule of Lease Related Balances [Table Text Block] Tabular disclosure of lease-related balances reported in the consolidated balance sheets. Non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Schedule of Gains and Losses on Debt Securities Available for Sale Schedule of Realized Gain (Loss) [Table Text Block] AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Amortized cost basis Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Less: Treasury (in shares) Treasury Stock, Common, Shares Interest rate swaps: receive-floating, pay-fixed Interest rate swaps - pay fixed, receive floating Represent Interest rate swaps, pay fixed, receive floating. Consolidation Items [Domain] Consolidation Items [Domain] Long-term borrowings Interest Expense, Other Long-Term Debt Derivative liability, statement of financial position [Extensible Enumeration] Derivative Liability, Statement of Financial Position [Extensible Enumeration] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] Term Extension Extended Maturity [Member] Unrealized/Unrecognized gains (losses) on debt securities: Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent [Abstract] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Federal Domestic Tax Jurisdiction [Member] Vested and outstanding at end of period (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Outstanding The number of equity-based payment instruments, excluding stock (or unit) options, that validly exist and are vested and outstanding, as of the balance sheet date. Financial Instruments Owned and Pledged as Collateral [Line Items] Financial Instruments Owned and Pledged as Collateral [Line Items] Estimated amount due, penalties (approximately) Income Tax Examination, Estimate of Possible Loss, Penalties Income Tax Examination, Estimate of Possible Loss, Penalties Business Combination, Contingent Consideration [Line Items] Business Combination, Contingent Consideration [Line Items] Less: Amounts representing interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Proceeds from sales of equity securities Proceeds from Sale of Equity Securities, FV-NI 2027 Time Deposit Maturities, Year One Commitments to extend credit Commitments to Extend Credit [Member] Limit where loans are processed through an expedited underwriting process Loans and Leases Receivable Limit above which Loans are Processed Through an Expedited Underwriting Process Represents the limit of loan where loans are processed through an expedited underwriting process. Total long-term borrowings Long-Term Debt, Gross Total undiscounted cash flows Lessee, Operating Lease, Liability, to be Paid Premises and equipment, net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Schedule of Regulatory Capital Requirements Applicable to Busey and Busey Bank Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Due after five years through ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value Total portfolio loans Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Provision for loan losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Excluding Business Acquisition Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Excluding Business Acquisition Securities sold under agreements to repurchase Securities sold under agreements to repurchase Securities Sold under Agreements to Repurchase Schedule of Revenue Recorded in Connection with Leases Operating Lease, Lease Income [Table Text Block] Schedule of Debt Securities in an Unrealized or Unrecognized Loss Position Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block] Expiration Date Trading Arrangement Expiration Date Decrease in other liabilities Increase (Decrease) in Other Operating Liabilities Minimum To Be Well Capitalized Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Unrealized net gains (losses) recognized on equity securities Equity Securities, FV-NI, Unrealized Gain (Loss) Impairment of mortgage servicing rights Mortgage Servicing Rights (MSR) Impairment (Recovery) Weighted average variable interest rates Derivative, Average Variable Interest Rate Schedule of Investments Equity Method Investments [Table Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Real estate construction Real estate construction Construction Loans [Member] Entity Current Reporting Status Entity Current Reporting Status Treasury management services Treasury Management Services [Member] Treasury Management Services Derivative [Line Items] Derivative [Line Items] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract] Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract] Consolidated Entities [Domain] Consolidated Entities [Domain] Cash paid for premiums on bank-owned life insurance Payment to Acquire Life Insurance Policy, Investing Activities (Gain) loss on sales of premises and equipment Gain (Loss) on Disposition of Property Plant Equipment Gross unrealized or unrecognized losses on debt securities Debt Securities Accumulated Gross Unrealized Loss Before Tax Gross total of unrealized losses on debt securities. Financial Instrument [Axis] Financial Instrument [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Foreign currency exchange forward contracts Foreign Exchange Forward [Member] 12 months or more Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Busey Bank Busey Bank Represents the information pertaining to Busey Bank. M&M Merchants And Manufacturers Bank Corporation [Member] Merchants And Manufacturers Bank Corporation Appraisal of collateral Valuation, Market Approach [Member] Current Fiscal Year End Date Current Fiscal Year End Date Less than 12 months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Total deposits Deposits OREO and other repossessed assets with subsequent impairment Other Real Estate Owned, Measurement Input Schedule of Distribution of Portfolio Loans Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Shares Remaining Available for Issuance Pursuant to the Plan (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Professional fees Professional Fees Fair Value Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Fair value recorded in other liabilities Derivative liabilities Derivative Liability Salaries, wages, and employee benefits Labor and Related Expense [Member] Labor and Related Expense Other noninterest expense Other Noninterest Expense Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Pass Pass [Member] Collateral held to secure obligations under derivative contracts Interest Rate Contract Interest Rate Contract [Member] Time deposits Time Deposits, at Carrying Value Total Gross unrealized or unrecognized losses on debt securities Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Equity securities Equity securities Equity Securities, FV-NI, Current Stock issued in acquisition, net of stock issuance costs Stock Issued During Period, Value, Acquisitions Net assets acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less) Anti-dilutive equity-based awards (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Leases not yet commenced commitments Unrecorded Unconditional Purchase Obligation Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Schedule of Held-to-Maturity Securities [Line Items] Schedule of Held-to-Maturity Securities [Line Items] Other servicing rights Other Servicing Asset at Fair Value Amount Represents the other servicing asset Collateral Pledged Collateral Pledged [Member] Schedule of Past Due and Non-accrual Loans and Non-Accrual Status Financing Receivable, Past Due [Table Text Block] Interest-bearing Interest-Bearing Deposit Liabilities Commitments [Table] Other Commitments [Table] LEASES Lessee, Operating Leases [Text Block] Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Measure: Measure [Axis] Provision for credit losses Financing Receivable, Credit Loss, Expense (Reversal) Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Fair value Derivative, Fair Value, Net Leverage Ratio of Tier 1 Capital to Average Assets, Amount Banking Regulation, Tier 1 Leverage Capital [Abstract] 5.000% Notes Maturing June 15, 2032 Fixed-to-floating rate notes due 2032 Represents the fixed-to-floating rate notes due 2032. Junior subordinated debt owed to unconsolidated trusts Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Liabilities, Junior Subordinated Notes Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Liabilities, Junior Subordinated Notes Debt securities held to maturity Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract] Retail loans Consumer Portfolio Segment [Member] Schedule of Reclassification of Unrealized Gains and Losses from OCI Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Total Capital to Risk Weighted Assets, Amount Banking Regulation, Total Capital [Abstract] Due after ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Entity Tax Identification Number Entity Tax Identification Number 2023, charge-off 2022, charge -off Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Derivative Derivative [Member] Interest income Interest And Dividend Income, Operating, Adjusted Interest And Dividend Income, Operating, Adjusted Net issuance of treasury stock for stock-based compensation plans Stock Issued During Period, Value, Stock Based Compensation Plans, Net Stock Issued During Period, Value, Stock Based Compensation Plans, Net Third-party dealer contracts Short [Member] Common shares issued (in shares) Common Stock, Shares, Issued Derivative asset, statement of financial position [Extensible Enumeration] Derivative Asset, Statement of Financial Position [Extensible Enumeration] Operating leases Operating Lease, Weighted Average Remaining Lease Term Commercial mortgage-backed securities Commercial mortgage-backed securities Commercial Mortgage-Backed Securities [Member] Card services and ATM fees Card Services And ATM Fees [Member] Card Services And ATM Fees Dividend equivalents earned (in shares) Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options, Dividend Equivalent Earned in Period Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options, Dividend Equivalent Earned in Period Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Number of risk participation agreements Number of Risk Participation Agreements Number of Risk Participation Agreements Security Exchange Name Security Exchange Name Rental income Lease Income 30-89 Days Financial Asset, 30 to 89 Days Past Due [Member] Financial Asset, 30 to 89 Days Past Due Mortgage banking derivative assets Interest rate lock commitments and forward sales commitments Represents interest rate lock commitments and forward sales commitments. 2028 Lessor, Operating Lease, Payment to be Received, Year Two PORTFOLIO LOANS Financing Receivables [Text Block] Line of credit maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Cash dividends on preferred stock Dividends, Preferred Stock Pledging Purpose [Axis] Pledging Purpose [Axis] Asset Class [Domain] Asset Class [Domain] (Gain) loss on sales of loans, net Gain Loss on Sale of Loans Net It represents the (gain) loss on sale of loans, net. Gains (losses) recognized in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Unrealized gains (losses) on cash flow hedges: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent [Abstract] Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Total cash and cash equivalents Cash and Cash Equivalent Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Provision for deferred income taxes expense (benefit) Increase (Decrease) in Deferred Income Taxes Common Common Stock Common Stock [Member] Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Finance Leases Finance Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Short-term borrowings Other Short-Term Borrowings Net increase in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Dilutive effect of outstanding equity-based awards (in shares) Weighted Average Number of Shares Outstanding, Diluted, Adjustment Statistical Measurement [Domain] Statistical Measurement [Domain] Prime Loan Swap Prime Loan Swap [Member] Prime Loan Swap Premises and equipment Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Collateral dependent loans secured by real estate or business assets Collateral Dependent Loans Represents collateral dependent loans secured by real estate or business assets. Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Short-term borrowings Short-Term Debt, Fair Value Remainder of 2026 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Gross interest income that would have been recorded if impaired loans had been current Financing Receivable, Nonaccrual, Interest Income OREO and other repossessed assets with subsequent impairment Real Estate Acquired in Satisfaction of Debt [Member] Asset Class [Axis] Asset Class [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Cash pledged to secure obligations under derivative contracts Interest Rate Swap Interest Rate Swap [Member] Leases [Abstract] Leases [Abstract] Total Debt securities with gross unrealized or unrecognized losses, fair value Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 2030 Lessor, Operating Lease, Payment to be Received, Year Four Schedule of Risk Grades of Portfolio Loans, Further Sorted by Origination Financing Receivable Credit Quality Indicators By Origination [Table Text Block] Tabular disclosure of financing receivables by credit quality indicator and origination. The credit quality indicator is a statistic about the credit quality of financing receivables. Examples include, but not limited to, consumer credit risk scores, credit-rating-agency ratings, an entity's internal credit risk grades, loan-to-value ratios, collateral, collection experience and other internal metrics. Non-Accrual Loans with No Allowance for Credit Losses Financing Receivable, Excluding Accrued Interest, Nonaccrual, No Allowance Pledged Status [Axis] Pledged Status [Axis] Limit above which loans are annually reviewed Loans and Leases Receivable, Limit Above Which Loans are Annually Reviewed Represents the limit of loan above which loans are reviewed annually. Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses Securities in Unrealized Loss Positions as Percentage of Aggregate Carrying Value Represents the total number of securities in the investment portfolio which are in an unrealized loss position as a percentage of the aggregate carrying value. Proceeds from other borrowings, net of debt issuance costs Proceeds from Other Debt Unrealized gross losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Remainder of 2026 Time Deposit Maturities, Remainder of Fiscal Year Basic earnings (loss) per common share (in dollars per share) Basic earnings (loss) per common share (in dollars per share) Earnings Per Share, Basic Common Stock, $0.001 par value Common Stock, $0.001 par value [Member] Common Stock, $0.001 par value Schedule of Information Relating to Operating Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Total short-term borrowings Short-Term Debt 2031 Time Deposit Maturities, Year Five C&I and other commercial Commercial And Industrial And Other Commercial [Member] Commercial And Industrial And Other Commercial Variable rate, commercial loans that are supported by the interest rate swap contracts Derivative Swap Type Variable Rate Amount of variable rate, commercial loans that are supported by the interest rate swap contracts. Unrecognized gross gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Measurement Input Type [Domain] Measurement Input Type [Domain] Schedule of Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis Fair Value Measurements, Nonrecurring [Table Text Block] 2029 Finance Lease, Liability, to be Paid, Year Three Charged-off Charged-off Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Obligations of U.S. government corporations and agencies Obligations of U.S. government corporations and agencies US Government Corporations and Agencies Securities [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Taxable interest income Interest Income, Securities, Operating, Taxable Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Other assets Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Other Assets Amount of other assets acquired at the acquisition date. Schedule of Foreign Currency Forward Contracts Schedule of Derivative Assets and Derivative Liabilities at Fair Value [Table Text Block] Schedule of Derivative Assets and Derivative Liabilities at Fair Value Unrealized holding gains (losses), net OCI, before Reclassifications, Net of Tax, Attributable to Parent Total stock-based compensation expense Share-Based Payment Arrangement, Expense Short-term borrowings Interest Expense, Short-Term Borrowings Excluding Federal Funds and Securities Sold under Agreements to Repurchase Hedging Designation [Domain] Hedging Designation [Domain] Count of debt securities Total Count Of Debt Securities, Held To Maturity Total count of held to maturity debt securities. Loans held for sale Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Range (Weighted Average) Fair Value Measurement Inputs and Valuation Techniques [Abstract] Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Total liabilities and stockholders’ equity Liabilities and Equity Stock issued in acquisition, net of stock issuance costs (in shares) Stock Issued During Period, Shares, Acquisitions Loss, receive-floating, pay-fixed Derivative, Gain (Losses) On Derivative Pay Fixed, Receive Floating Amount of increase (decrease) in the fair value of derivatives pay fixed receive floating recognized in the income statement. 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Ratio, Capital Adequacy, Minimum Fair Value Fair Value Debt securities held to maturity Debt Securities, Held-to-Maturity, Fair Value 2027 Finance Lease, Liability, to be Paid, Year One Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Right of use assets obtained in exchange for operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Lease costs Lease, Cost [Abstract] Debt Securities, Available-for-Sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Total assets acquired Business Combination, Recognized Asset Acquired, Asset Level 2 Inputs Fair Value, Inputs, Level 2 [Member] Short-term borrowings Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Short-Term Debt Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Short-Term Debt Credit Commitments and Contingencies Fair Value, off-Balance-Sheet Risks, Disclosure Information [Line Items] Investments in unconsolidated entities Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] Operating Leases Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Total pledged loans Asset Pledged as Collateral [Member] Plan Name [Axis] Plan Name [Axis] Document Information [Table] Document Information [Table] PEO PEO [Member] Actual Banking Regulation, Tier 1 Leverage Capital, Actual Schedule of Maturities of Debt Securities Investments Classified by Contractual Maturity Date [Table Text Block] Due in one year or less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Financial Asset Acquired with Credit Deterioration Financial Asset Acquired with Credit Deterioration [Member] Actual Banking Regulation, Common Equity Tier 1 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amount Derivative, Notional Amount Intersegment interest income Intersegment Interest Income Intersegment Interest Income Cash flows related to leases Cash Flow, Operating Activities, Lessee [Abstract] Revolving Loans Financing Receivable, Excluding Accrued Interest, Revolving Schedule of Estimated Acquisition-Date Fair Values of the Assets Acquired and Liabilities Assumed Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] Fair Value Fair Value Measurements, Nonrecurring Value Measurement [Abstract] Junior subordinated debt owed to unconsolidated trusts Interest Expense, Junior Subordinated Debentures City Area Code City Area Code Schedule of Loans Evaluated Individually, Segregated by Loan Category and Class Financing Receivable, Allowance for Credit Loss [Table Text Block] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock [Member] 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES Investment [Text Block] Other expense Other Noninterest Expense [Member] Other Noninterest Expense Junior subordinated debt owed to unconsolidated trusts Junior subordinated debt owed to unconsolidated trusts Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust Cash flows provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Accrued interest receivable Interest Receivable Estimated amount due Income Tax Examination, Estimate of Possible Loss Total lease cost Lease, Cost Cash Flow Hedging Cash Flow Hedging [Member] Other liabilities Other Liabilities Goodwill Goodwill Schedule of Lease Costs and Other Lease Information Lease, Cost [Table 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[Axis] Restricted cash Restricted Cash Fair Value Measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Financial liabilities Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Credit Loss Status [Axis] Credit Loss Status [Axis] Entity [Domain] Entity [Domain] Net cash provided by investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Financial Statement Presentation Basis of Accounting, Policy [Policy Text Block] Operating leases Operating Lease, Right-of-Use Asset Premises and Equipment rent expense Operating Lease, Cost Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Carrying Amount Reported Value Measurement [Member] Plan Name [Domain] Plan Name [Domain] Pre-tax acquisition expenses Business Combination, Acquisition-Related Cost, Expense Weighted average period over which expense is to be recognized on awards issued under Busey's 2020 Equity Plan Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Fair Value Debt Securities, Held-to-Maturity, Fair Value, Maturity [Abstract] Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Intersegment noninterest expense Intersegment Noninterest Expense Intersegment Noninterest Expense Day 1 PCD Financing Receivable, Excluding Accrued Interest, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date Non-Accrual Loans Financing Receivable, Nonaccrual OPERATING SEGMENTS AND RELATED INFORMATION Segment Reporting Disclosure [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Other Commitments [Line Items] Other Commitments [Line Items] Increase (decrease) in shareholders' equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Data processing Information Technology and Data Processing Unrealized Losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Substandard Non-accrual Doubtful [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Comprehensive Income (Loss) Note [Text Block] Weighted Average Weighted Average [Member] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Net deferred loan origination costs Financing Receivable, Unamortized Loan Cost (Fee) Amortization of intangible assets Amortization of intangible assets Amortization of Intangible Assets Tax credit investments Tax Credit Investments [Member] Tax Credit Investments Unrealized Gains (Losses) on Debt Securities Available For Sale and Unrealized Gains (Losses) on Cash Flow Hedges AOCI, Accumulated Gain (Loss, Debt Securities, Available-For-Sale, Parent And Accumulated Gain (loss), Net, Cash Flow Hedge, Parent [Member] AOCI, Accumulated Gain (Loss, Debt Securities, Available-For-Sale, Parent And Accumulated Gain (loss), Net, Cash Flow Hedge, Parent Total lease liabilities Leases, Liability Leases, Liability Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization of premises and equipment Depreciation, Depletion and Amortization Count of debt securities in an unrealized or unrecognized loss position Debt Securities, Held To Maturity, Unrealized Loss Position, Number of Positions Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (held to maturity), in unrealized loss position. Residential mortgage-backed securities Residential mortgage-backed securities Residential Mortgage-Backed Securities [Member] Revolving Credit Facility Revolving Credit Facility [Member] Finance leases Present value of net future minimum lease payments Finance lease liabilities Finance Lease, Liability Arrangement Duration Trading Arrangement Duration Intersegment interest expense Intersegment Interest Expense Intersegment Interest Expense Segments [Axis] Segments [Axis] Common Equity Tier 1 Capital to Risk Weighted Assets, Amount Common Equity Tier One Risk Based Capital [Abstract] No definition available. Tier 1 Capital to Risk Weighted Assets, Ratio Banking Regulation, Risk-Based Information [Abstract] Intersegment noninterest income Intersegment Noninterest Income Intersegment Noninterest Income Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] STOCK-BASED COMPENSATION Share-Based Payment Arrangement [Text Block] Other intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill Cash and cash equivalents Business Combination, Recognized Asset Acquired, Cash and Cash Equivalent Assets Assets [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent CrossFirst CrossFirst Bankshares, Inc [Member] CrossFirst Bankshares, Inc Debt Instrument [Axis] Debt Instrument [Axis] FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Banking and Thrift, Other Disclosures [Abstract] Banking and Thrift, Other Disclosure [Abstract] Business Combination [Line Items] Business Combination [Line Items] Stockholders’ equity Equity, Attributable to Parent [Abstract] Proceeds from short-term borrowings Proceeds from Short-Term Debt Schedule of Loan Modifications for Borrowers Experiencing Financial Difficulty Financing Receivable, Modified [Table Text Block] Repurchase of stock, including excise tax Treasury Stock, Value, Acquired, Cost Method Investment, Name [Axis] Investment, Name [Axis] Interest rate Debt Instrument, Interest Rate, Stated Percentage 30 to 59 days past due and still accruing Financial Asset, 30 to 59 Days Past Due [Member] Number of leases not yet commenced Number Of Leases Not Yet Commenced Number Of Leases Not Yet Commenced Commitment to lend Financing Receivable, Modified, Commitment to Lend Entity Registrant Name Entity Registrant Name Unrealized gains expected to be reclassified from OCI to interest income Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months 2020 Equity Plan 2020 Equity Plan [Member] 2020 Equity Plan Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Minimum To Be Well Capitalized Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum Total Capital to Risk Weighted Assets, Ratio Capital to Risk Based Ratios [Abstract] Capital to Risk Based Ratios [Abstract] Bank property held for sale with impairment Alternative Investment, Measurement Input Count of debt securities in an unrealized or unrecognized loss position Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Deposits: Deposits [Abstract] Number of operating segments Number of Operating Segments Mortgage servicing rights Servicing Asset at Fair Value, Amount Net amortization (accretion) of premium (discount) on investment securities Accretion (Amortization) of Discounts and Premiums, Investments Purchases of equity securities Payments to Acquire Equity Securities, FV-NI Banking Banking Represents information pertaining to Banking segment. Restatement Determination Date: Restatement Determination Date [Axis] Repayment of other borrowings Repayments of Other Debt Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Schedule of the Interest-Rate Swaps Designated as Cash Flow Hedges Schedule of Interest Rate Derivatives [Table Text Block] Due after five years through ten years Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost Liabilities assumed Business Combination, Recognized Liability Assumed, Liability [Abstract] Name Trading Arrangement, Individual Name Schedule of Short-term Debt [Table] Short-Term Debt [Table] Loans held for sale Loan, Held-for-Sale, Fair Value Disclosure Issuance of debt Principal balance Debt Instrument, Face Amount Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position Fair Value [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position Fair Value Common stock, preferred stock and replacement awards Business Combination, Consideration Transferred, Equity Interest Interest- Bearing Time Deposits in Other Banks Interest- Bearing Time Deposits In Other Banks, Policy [Policy Text Block] Interest- Bearing Time Deposits In Other Banks, Policy Preferred Preferred stock Preferred Stock [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Interest premium (discount) specific to PCD financial assets Business Combination, Interest (Premium) Discount Specific To PCD Financial Assets Business Combination, Interest (Premium) Discount Specific To PCD Financial Assets Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Treasury stock at cost Treasury Stock, Value Tax effect OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Other investments in unconsolidated entities Other Investments In Unconsolidated Entities [Member] Other Investments In Unconsolidated Entities Segments [Domain] Segments [Domain] Credit Loss Status [Domain] Credit Loss Status [Domain] Income Statement Location [Axis] Statement of Income Location, Balance [Axis] DEBT SECURITIES Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Balance Sheet Location [Domain] Statement of Financial Position Location, Balance [Domain] Derivative assets not designated as hedging instruments Mortgage banking derivative assets Derivative Asset [Abstract] Unrealized Gains (Losses) on Debt Securities Available For Sale AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Interest expense Interest Expense, Operating and Nonoperating [Abstract] Purchases of debt securities available for sale Payments to Acquire Debt Securities, Available-for-Sale Preferred stock, $0.001 par value, liquidation preference $222,750 at March 31, 2026, and December 31, 2025 Preferred stock, value, issued Preferred Stock, Value, Issued Obligations of states and political subdivisions Obligations of states and political subdivisions US States and Political Subdivisions Debt Securities [Member] Accrued interest payable Interest Payable Subordinated notes, net of unamortized issuance costs Subordinated Debt 2025 2024 Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Total liabilities assumed Business Combination, Recognized Liability Assumed, Liability Subordinated Debt Subordinated Debt [Member] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] All Executive Categories All Executive Categories [Member] Series A Non-Cumulative Perpetual Preferred Stock Series A Non-Cumulative Perpetual Preferred Stock [Member] Series A Non-Cumulative Perpetual Preferred Stock Common stock, $0.001 par value Common Stock, Value, Issued Time deposits by schedule of maturities Time Deposits, Fiscal Year Maturity [Abstract] Finance leases Finance Lease, Right-of-Use Asset, after Accumulated Amortization Interest and fees on loans Interest and Fee Income, Loans and Leases Net amortization (accretion) of premium (discount) on FHLB advances and other borrowings Amortization of Discount on Federal Home Loan Bank, Advances Amount of amortized discount on outstanding advances and other borrowings (including trust preferred securities) made and reported by Federal Home Loan Bank (FHLBank). Schedule of Unamortized Debt Issuance Cost Schedule of Unamortized Debt Issuance Cost [Table Text Block] Tabular disclosure of unamortized debt issuance cost. Outstanding commitments and contingent liabilities (see Notes 5 and 11) Commitments and Contingencies Preferred stock, liquidation preference Preferred Stock, Liquidation Preference, Value 2026, charge-off 2025, charge-off Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Writeoff All other noninterest expense Other Noninterest Expense, Adjusted Other Noninterest Expense, Adjusted Count of debt securities Total Count Of Debt Securities Total count of debt securities. Business Combination [Axis] Business Combination [Axis] Long-term borrowings Other Long-Term Debt Schedule of Changes in Busey’s Outstanding Equity Awards Schedule of Nonvested Share Activity [Table Text Block] Fair value adjustments Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred Interest Income Interest Income [Member] Loans in the process of foreclosure Mortgage Loans in Process of Foreclosure, Amount Short-Term Debt [Line Items] Short-Term Debt [Line Items] Cash payments for: Cash Payments [Abstract] No definition available. (Gain) loss on sales of OREO and other repossessed assets Gains (Losses) On Sales Of Other Real Estate And Other Repossessed Assets Gains (Losses) On Sales Of Other Real Estate And Other Repossessed Assets PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Portfolio loans, net of ACL Business Combination, Recognized Identifiable Assets Acquired And Liabilities, Financing Receivables Business Combination, Recognized Identifiable Assets Acquired And Liabilities, Financing Receivables 60 to 89 days past due and still accruing Financial Asset, 60 to 89 Days Past Due [Member] Hedging Designation [Axis] Hedging Designation [Axis] Equity securities Securities Equity Investments [Member] Represents the securities equity investments. Derivative Contract [Domain] Derivative Contract [Domain] Reclassification adjustment for realized (gains) losses on cash flow hedges included in net income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Gross losses on debt securities Debt Securities, Available-for-Sale, Realized Loss Due after ten years Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 10 All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Expired (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Expirations Purchases of premises and equipment Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Weighted average rate for securities sold under agreements to repurchase Debt, weighted average interest rate (as a percent) Debt, Weighted Average Interest Rate Cash and cash equivalents: Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Trust Assets Assets Held in Trust [Policy Text Block] Disclosure of accounting policy for assets under care held for customers, that are not included in the Company's consolidated financial statements. 2022, charge-off 2021, charge-off Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Other Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent, Alternative [Abstract] Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-Maturity [Table] Schedule of Notional Amount and Fair Value of Risk Participation Agreement Schedule of Derivative Instruments [Table Text Block] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Held to Maturity Held to Maturity, Debt Securities in Unrealized Loss Position [Abstract] N/A Weighted average rate: receive-fixed Derivative, Average Fixed Interest Rate Total Gross unrealized or unrecognized losses on debt securities Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Derivative liabilities not designated as hedging instruments Mortgage banking derivative liabilities Derivative Liability [Abstract] Commercial loans Commercial Portfolio Segment [Member] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Revenue (net interest income plus noninterest income) Business Combination, Pro Forma Information, Pro Forma Revenue LEASES Lessor, Operating Leases [Text Block] Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses Available For Sale Securities in Unrealized Loss Positions as Percentage of Aggregate Carrying Value Represents the total number of securities in the investment portfolio which are in an unrealized loss position as a percentage of the aggregate carrying value. Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Title of 12(b) Security Title of 12(b) Security Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Provision for credit losses Provision for loan losses and Day 2 Provision for loan losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Due in one year or less Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost OCI: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Federal Reserve Bank Federal Reserve Bank [Member] Federal Reserve Bank Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table] Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table] Furniture and equipment expenses Equipment Expense Estimated amount due, interest Income Tax Examination, Estimate of Possible Loss, Interest Income Tax Examination, Estimate of Possible Loss, Interest Count of debt securities in an unrealized or unrecognized loss position Debt Securities, Unrealized Loss Position, Number of Positions Total count of debt securities in an unrealized loss position. Earnings Per Share [Abstract] Earnings Per Share [Abstract] 2031 Lessee, Operating Lease, Liability, to be Paid, Year Five Federal funds purchased and securities sold under agreements to repurchase Interest Expense, Securities Sold under Agreements to Repurchase Risk participation agreements purchased Risk Participation Agreement Purchased [Member] Risk Participation Agreement Purchased Pre-tax loss on debt securities Debt Securities, Available-for-Sale, Realized Loss, Before Tax Debt Securities, Available-for-Sale, Realized Loss, Before Tax Schedule of Interest Income (Expense) Recorded on Swap Transactions Interest Income and Interest Expense Disclosure [Table Text Block] 2024, charge-off 2023, charge-off Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures Cash surrender value of bank owned life insurance Cash Surrender Value of Life Insurance Securities Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Securities Available For Sale Amount of investments in debt and equity securities, available-for-sale, acquired at the acquisition date. Repurchase of stock, including excise tax (in shares) Treasury Stock, Shares, Acquired Thereafter Finance Lease, Liability, to be Paid, after Year Five Award Timing Disclosures [Line Items] Securities sold under agreements to repurchase Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure Measurement Frequency [Domain] Measurement Frequency [Domain] FHLB advances maturing in less than one year from date of origination, and the current portion of long-term FHLB advances due within 12 months Federal Home Loan Bank Advances [Member] Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Exercised Right of use assets: Right Of Use Assets [Abstract] Right Of Use Assets Gain, receive-fixed, pay-floating Derivative, Gain, (Losses) on Derivative Pay Floating, Receive Fixed Amount of increase (decrease) in the fair value of derivatives pay floating receive fixed recognized in the income statement. Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Portfolio loans (net of ACL of $169,054 at March 31, 2026, and $174,023 at December 31, 2025) Portfolio loans, net Portfolio loans, net Pledged loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss ILLINOIS ILLINOIS Proceeds from sales of mortgage loans Proceeds from Sale, Loan, Mortgage, Held-for-Sale Net income (loss) Net income (loss) Net income (loss) Net Income (Loss) Attributable to Parent Operating lease costs: Operating Lease, Liability [Abstract] Actual Banking Regulation, Total Risk-Based Capital Ratio, Actual Mortgage revenue Gain (Loss) on Sale of Mortgage Loans Activity in the allowance for loan losses Accounts Receivable, Allowance for Credit Loss [Roll Forward] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Purchase of treasury stock Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Brokered time deposits Brokered Time Deposits Represents the amount of brokered time deposits. FHLB borrowings Federal Home Loan Bank Certificates and Obligations (FHLB) [Member] Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Retained earnings Retained Earnings (Accumulated Deficit) Net (increase) decrease in loans Net Increase (Decrease) In Financing Receivables, Investing Activities Net Increase (Decrease) In Financing Receivables, Investing Activities Schedule of Stock-Based Compensation Expense Share-Based Payment Arrangement, Cost by Plan [Table Text Block] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Loans previously charged-off prior to acquisition Business Combination, Loans Previously Charged Off Business Combination, Loans Previously Charged Off Increase in cash surrender value of bank owned life insurance Life Insurance, Corporate or Bank Owned, Change in Value Class of Stock [Axis] Class of Stock [Axis] Unrealized Gains (Losses) on Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Dividend income on bank stock Investment Income, Dividend Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Total right of use assets Leases, Right-Of-Use Asset Leases, Right-Of-Use Asset Statement [Table] Statement [Table] Schedule of Reconciliation Between the Purchase Price and the Fair Value Business Combination [Table Text Block] Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cash flows provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Schedule of Amortized Cost, Unrealized or Unrecognized Gains and Losses and Fair Values of Securities Classified Available for Sale and Held to Maturity Schedule of Available For Sale and Held to Maturity Securities Reconciliation [Table Text Block] Tabular disclosure of the reconciliation of available-for-sale and held to maturity securities from cost basis to fair value. Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Appraisal of collateral or real estate listing price Appraisal of collateral or real estate listing price Representing information pertaining to Appraisal of collateral or real estate listing price valuation technique used to measure fair value. All Adjustments to Compensation All Adjustments to Compensation [Member] Amendment Flag Amendment Flag Fair Value Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Number of notes Debt Instrument, Number Of Notes Debt Instrument, Number Of Notes Gross contractual amounts of acquired receivables Gross contractual receivable for PCD financial assets Business Combination, Acquired Receivable, Purchased without Credit Deterioration, Gross Contractual Amount Termination Date Trading Arrangement Termination Date Interest-bearing deposits Interest-Bearing Deposits in Banks and Other Financial Institutions Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] 2029 Time Deposit Maturities, Year Three Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration] Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration] Portfolio loans, allowance for credit losses ACL ACL beginning balance ACL ending balance Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Due in one year or less Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Year One Operating leases Operating Lease, Weighted Average Discount Rate, Percent CrossFirst Awards CrossFirst Awards [Member] CrossFirst Awards Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Weighted average number of common shares outstanding, basic (in shares) Weighted Average Number of Shares Outstanding, Basic Schedule of Computation of Earnings Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Exercisable at end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Realized net gains (losses) on debt securities Debt Securities, Available-for-Sale, Realized Gain (Loss) Net unrealized holding gains (losses) on debt securities available for sale OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Schedule of Composition of Deposits Schedule of Deposit Liabilities [Table Text Block] Tabular disclosure for deposit liabilities classified by their types and nature. Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Balance outstanding Line of Credit Facility, Fair Value of Amount Outstanding Use of Estimates Use of Estimates, Policy [Policy Text Block] Actual Banking Regulation, Total Capital, Actual Operating cash flows from finance leases Finance Lease, Interest Payment on Liability Financial Instruments Owned and Pledged as Collateral [Table] Financial Instruments Owned and Pledged as Collateral [Table] Long-term borrowings Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Liabilities, Long-Term Debt Excluding Subordinated Notes Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Liabilities, Long-Term Debt Excluding Subordinated Notes Cash dividends paid Payments of Dividends Net occupancy expense of premises Occupancy, Net Net change in unrealized gains (losses) on cash flow hedges, net of tax Derivative, Excluded Component, Gain (Loss), Recognized in Earnings Insider Trading Arrangements [Line Items] Prior Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Current Financial Asset, Not Past Due [Member] Unrecognized Losses Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss [Abstract] Total liabilities Liabilities Interest rate lock commitments Interest Rate Lock Commitments [Member] 2031 Finance Lease, Liability, to be Paid, Year Five % of total class of financing receivable Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Other repossessed assets Other Real Estate, Foreclosed Assets, and Repossessed Assets Pre-tax costs to consummate the merger Business Combination, Acquisition Related Costs, Legal, Professional And Consulting Fees Business Combination, Acquisition Related Costs, Legal, Professional And Consulting Fees Cash Payments To Acquire Business, Gross And Other Consideration Transferred Payments To Acquire Business, Gross And Other Consideration Transferred Issuance of preferred stock, net of issuance costs Stock Issued During Period, Value, New Issues Asset-backed securities Asset-backed securities Asset-Backed Securities [Member] Consolidation Items [Axis] Consolidation Items [Axis] Subordinated notes Interest Expense, Subordinated Notes and Debentures Net accretable purchase accounting adjustments Finance Receivable, Excluding Accrued Interest, Net Accretable Purchase Accounting Adjustments Finance Receivable, Excluding Accrued Interest, Net Accretable Purchase Accounting Adjustments Counterparty Name [Axis] Counterparty Name [Axis] Proceeds from paydowns and maturities of debt securities held to maturity Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities Total stockholders’ equity before treasury stock Stockholders' Equity before Treasury Stock Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Corporate debt securities Corporate debt securities Corporate Debt Securities [Member] Secured Overnight Financing Rate (SOFR) [Member]