0000001 - Document - Cover Page link:presentationLink link:calculationLink link:definitionLink 0000002 - Document - Audit Information link:presentationLink link:calculationLink link:definitionLink 0000003 - Statement - CONSOLIDATED BALANCE SHEETS link:presentationLink link:calculationLink link:definitionLink 0000004 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 0000005 - Statement - CONSOLIDATED STATEMENTS OF INCOME link:presentationLink link:calculationLink link:definitionLink 0000006 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME link:presentationLink link:calculationLink link:definitionLink 0000007 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 0000008 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 0000009 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 0000010 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 0000011 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES link:presentationLink link:calculationLink link:definitionLink 0000012 - Disclosure - ACQUISITIONS link:presentationLink link:calculationLink link:definitionLink 0000013 - Disclosure - DEBT SECURITIES link:presentationLink link:calculationLink link:definitionLink 0000014 - Disclosure - PORTFOLIO LOANS link:presentationLink link:calculationLink link:definitionLink 0000015 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS link:presentationLink link:calculationLink link:definitionLink 0000016 - Disclosure - PREMISES AND EQUIPMENT link:presentationLink link:calculationLink link:definitionLink 0000017 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS link:presentationLink link:calculationLink link:definitionLink 0000018 - Disclosure - DEPOSITS link:presentationLink link:calculationLink link:definitionLink 0000019 - Disclosure - BORROWINGS link:presentationLink link:calculationLink link:definitionLink 0000020 - Disclosure - JUNIOR SUBORDINATED DEBT OWED TO UNCOLSOLIDATED TRUSTS link:presentationLink link:calculationLink link:definitionLink 0000021 - Disclosure - REGULATORY CAPITAL link:presentationLink link:calculationLink link:definitionLink 0000022 - Disclosure - INCOME TAXES link:presentationLink link:calculationLink link:definitionLink 0000023 - Disclosure - EMPLOYEE BENEFIT PLANS link:presentationLink link:calculationLink link:definitionLink 0000024 - Disclosure - STOCK-BASED COMPENSATION link:presentationLink link:calculationLink link:definitionLink 0000025 - Disclosure - TRANSACTIONS WITH RELATED PARTIES link:presentationLink link:calculationLink link:definitionLink 0000026 - Disclosure - OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES link:presentationLink link:calculationLink link:definitionLink 0000027 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS link:presentationLink link:calculationLink link:definitionLink 0000028 - Disclosure - FAIR VALUE MEASUREMENTS link:presentationLink link:calculationLink link:definitionLink 0000029 - Disclosure - EARNINGS PER SHARE link:presentationLink link:calculationLink link:definitionLink 0000030 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) link:presentationLink link:calculationLink link:definitionLink 0000031 - Disclosure - OPERATING SEGMENTS AND RELATED INFORMATION link:presentationLink link:calculationLink link:definitionLink 0000032 - Disclosure - LEASES link:presentationLink link:calculationLink link:definitionLink 0000033 - Disclosure - PARENT COMPANY ONLY FINANCIAL INFORMATION link:presentationLink link:calculationLink link:definitionLink 0000034 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies) link:presentationLink link:calculationLink link:definitionLink 0000035 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000036 - Disclosure - ACQUISITIONS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000037 - Disclosure - DEBT SECURITIES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000038 - Disclosure - PORTFOLIO LOANS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000039 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000040 - Disclosure - PREMISES AND EQUIPMENT (Tables) link:presentationLink link:calculationLink link:definitionLink 0000041 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000042 - Disclosure - DEPOSITS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000043 - Disclosure - BORROWINGS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000044 - Disclosure - REGULATORY CAPITAL (Tables) link:presentationLink link:calculationLink link:definitionLink 0000045 - Disclosure - INCOME TAXES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000046 - Disclosure - EMPLOYEE BENEFIT PLANS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000047 - Disclosure - STOCK-BASED COMPENSATION (Tables) link:presentationLink link:calculationLink link:definitionLink 0000048 - Disclosure - TRANSACTIONS WITH RELATED PARTIES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000049 - Disclosure - OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000050 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000051 - Disclosure - FAIR VALUE MEASUREMENTS (Tables) link:presentationLink link:calculationLink link:definitionLink 0000052 - Disclosure - EARNINGS PER SHARE (Tables) link:presentationLink link:calculationLink link:definitionLink 0000053 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables) link:presentationLink link:calculationLink link:definitionLink 0000054 - Disclosure - OPERATING SEGMENTS AND RELATED INFORMATION (Tables) link:presentationLink link:calculationLink link:definitionLink 0000055 - Disclosure - LEASES (Tables) link:presentationLink link:calculationLink link:definitionLink 0000056 - Disclosure - PARENT COMPANY ONLY FINANCIAL INFORMATION (Tables) link:presentationLink link:calculationLink link:definitionLink 0000057 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Trust Assets (Details) link:presentationLink link:calculationLink link:definitionLink 0000058 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Securities (Details) link:presentationLink link:calculationLink link:definitionLink 0000059 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Loan Servicing (Details) link:presentationLink link:calculationLink link:definitionLink 0000060 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Portfolio Loans (Details) link:presentationLink link:calculationLink link:definitionLink 0000061 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Premises and Equipment (Details) link:presentationLink link:calculationLink link:definitionLink 0000062 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Other Intangibles (Details) link:presentationLink link:calculationLink link:definitionLink 0000063 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Cash Surrender Value of Bank Owned Life Insurance (Details) link:presentationLink link:calculationLink link:definitionLink 0000064 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - FHLB Stock (Details) link:presentationLink link:calculationLink link:definitionLink 0000065 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Other Asset Investments (Details) link:presentationLink link:calculationLink link:definitionLink 0000066 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Income Taxes (Details) link:presentationLink link:calculationLink link:definitionLink 0000067 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Stock-Based Employee Compensation (Details) link:presentationLink link:calculationLink link:definitionLink 0000068 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Segment Disclosure (Details) link:presentationLink link:calculationLink link:definitionLink 0000069 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Off Balance Sheet Arrangements (Details) link:presentationLink link:calculationLink link:definitionLink 0000070 - Disclosure - ACQUISITIONS - Cummins-American Corp. (Details) link:presentationLink link:calculationLink link:definitionLink 0000071 - Disclosure - Acquisitions - Schedule of fair value estimates of assets acquired and liabilities assumed (Details) link:presentationLink link:calculationLink link:definitionLink 0000072 - Disclosure - DEBT SECURITIES - Schedule of Amortized Cost, Unrealized Gains and Losses, and Fair Values of Securities Classified as AFS and HTM (Details) link:presentationLink link:calculationLink link:definitionLink 0000073 - Disclosure - DEBT SECURITIES - Maturity of Debt Securities (Details) link:presentationLink link:calculationLink link:definitionLink 0000074 - Disclosure - DEBT SECURITIES - Gains and losses on debt securities (Details) link:presentationLink link:calculationLink link:definitionLink 0000075 - Disclosure - DEBT SECURITIES - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000076 - Disclosure - DEBT SECURITIES - Debt securities in an unrealized loss position (Details) link:presentationLink link:calculationLink link:definitionLink 0000077 - Disclosure - DEBT SECURITIES - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 0000078 - Disclosure - PORTFOLIO LOANS - Distribution of portfolio loans (Details) link:presentationLink link:calculationLink link:definitionLink 0000079 - Disclosure - PORTFOLIO LOANS - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000080 - Disclosure - PORTFOLIO LOANS - Schedule of financial instruments owned and pledged as collateral (Details) link:presentationLink link:calculationLink link:definitionLink 0000081 - Disclosure - PORTFOLIO LOANS - Summary of risk grades segregated by category of portfolio loans (Details) link:presentationLink link:calculationLink link:definitionLink 0000082 - Disclosure - PORTFOLIO LOANS - Risk grades of portfolio loans, further sorted by origination year (Details) link:presentationLink link:calculationLink link:definitionLink 0000083 - Disclosure - PORTFOLIO LOANS -Summary of portfolio loans that are past due and still accruing or on a non-accrual status (Details) link:presentationLink link:calculationLink link:definitionLink 0000084 - Disclosure - PORTFOLIO LOANS - Summary of TDR Loans (Details) link:presentationLink link:calculationLink link:definitionLink 0000085 - Disclosure - PORTFOLIO LOANS - Summarize TDRs (Details) link:presentationLink link:calculationLink link:definitionLink 0000086 - Disclosure - PORTFOLIO LOANS - Schedule of loans modified under the CARES Act or Interagency Statement (Details) link:presentationLink link:calculationLink link:definitionLink 0000087 - Disclosure - PORTFOLIO LOANS - Schedule of details of impaired loans, segregated by category (Details) link:presentationLink link:calculationLink link:definitionLink 0000088 - Disclosure - PORTFOLIO LOANS - Schedule of activity on the allowance for loan losses (Details) link:presentationLink link:calculationLink link:definitionLink 0000089 - Disclosure - PORTFOLIO LOANS - Schedule of allowance for loan losses and recorded investments in portfolio loans, by category (Details) link:presentationLink link:calculationLink link:definitionLink 0000090 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS - Summary of OREO and other repossessed assets balances (Details) link:presentationLink link:calculationLink link:definitionLink 0000091 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS - Summary of activity related to OREO and other repossessed assets (Details) link:presentationLink link:calculationLink link:definitionLink 0000092 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000093 - Disclosure - OTHER REAL ESTATE OWNED AND OTHER REPOSSESSED ASSETS - Expenses related to OREO and other repossessed assets (Details) link:presentationLink link:calculationLink link:definitionLink 0000094 - Disclosure - PREMISES AND EQUIPMENT - Summary of premises and equipment, net (Details) link:presentationLink link:calculationLink link:definitionLink 0000095 - Disclosure - PREMISES AND EQUIPMENT - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000096 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000097 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of carrying amount of goodwill by operating segment (Details) link:presentationLink link:calculationLink link:definitionLink 0000098 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of other intangible asset disclosures (Details) link:presentationLink link:calculationLink link:definitionLink 0000099 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of amortization expense relating to intangible assets (Details) link:presentationLink link:calculationLink link:definitionLink 0000100 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Estimated Amortization Expense (Details) link:presentationLink link:calculationLink link:definitionLink 0000101 - Disclosure - DEPOSITS - Schedule of composition of deposits (Details) link:presentationLink link:calculationLink link:definitionLink 0000102 - Disclosure - DEPOSITS - Schedule of maturities of time deposits (Details) link:presentationLink link:calculationLink link:definitionLink 0000103 - Disclosure - BORROWINGS - Securities sold under agreements to repurchase (Details) link:presentationLink link:calculationLink link:definitionLink 0000104 - Disclosure - BORROWINGS - Term Loan (Details) link:presentationLink link:calculationLink link:definitionLink 0000105 - Disclosure - BORROWINGS - Short-term borrowings (Details) link:presentationLink link:calculationLink link:definitionLink 0000106 - Disclosure - BORROWINGS - Long-term Debt (Details) link:presentationLink link:calculationLink link:definitionLink 0000107 - Disclosure - BORROWINGS - Senior Notes and Subordinate Notes (Details) link:presentationLink link:calculationLink link:definitionLink 0000108 - Disclosure - BORROWINGS - Schedule of unamortized debt issuance cost (Details) link:presentationLink link:calculationLink link:definitionLink 0000109 - Disclosure - JUNIOR SUBORDINATED DEBT OWED TO UNCOLSOLIDATED TRUSTS (Details) link:presentationLink link:calculationLink link:definitionLink 0000110 - Disclosure - REGULATORY CAPITAL - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000111 - Disclosure - REGULATORY CAPITAL - Capital Amounts and Ratios (Details) link:presentationLink link:calculationLink link:definitionLink 0000112 - Disclosure - INCOME TAXES - Schedule of the components of income taxes (Details) link:presentationLink link:calculationLink link:definitionLink 0000113 - Disclosure - INCOME TAXES - Schedule of the reconciliation of federal and state income taxes at statutory rates to the income taxes included in the statements of income (Details) link:presentationLink link:calculationLink link:definitionLink 0000114 - Disclosure - INCOME TAXES - Schedule of the deferred tax assets and liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 0000115 - Disclosure - INCOME TAXES - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000116 - Disclosure - EMPLOYEE BENEFIT PLANS - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000117 - Disclosure - EMPLOYEE BENEFIT PLANS - Schedule of expenses related to the employee benefit plans (Details) link:presentationLink link:calculationLink link:definitionLink 0000118 - Disclosure - STOCK-BASED COMPENSATION - Award Status (Details) link:presentationLink link:calculationLink link:definitionLink 0000119 - Disclosure - STOCK-BASED COMPENSATION - 2020 Equity Plan (Details) link:presentationLink link:calculationLink link:definitionLink 0000120 - Disclosure - STOCK-BASED COMPENSATION - Summary of changes in the Company's RSU, PSU, and DSU awards (Details) link:presentationLink link:calculationLink link:definitionLink 0000121 - Disclosure - STOCK-BASED COMPENSATION - 2021 Employee Stock Purchase Plan (Details) link:presentationLink link:calculationLink link:definitionLink 0000122 - Disclosure - STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) link:presentationLink link:calculationLink link:definitionLink 0000123 - Disclosure - STOCK-BASED COMPENSATION - Schedule of Unamortized Stock-Based Compensation Expense (Details) link:presentationLink link:calculationLink link:definitionLink 0000124 - Disclosure - TRANSACTIONS WITH RELATED PARTIES (Details) link:presentationLink link:calculationLink link:definitionLink 0000125 - Disclosure - OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES (Details) link:presentationLink link:calculationLink link:definitionLink 0000126 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of financial instruments owned and pledged as collateral (Details) link:presentationLink link:calculationLink link:definitionLink 0000127 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 0000128 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Summary of the interest-rate swaps designated as cash flow hedges (Details) link:presentationLink link:calculationLink link:definitionLink 0000129 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Reclassification of unrealized gains and losses from OCI (Details) link:presentationLink link:calculationLink link:definitionLink 0000130 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of interest income (expense) recorded on swap transactions (Details) link:presentationLink link:calculationLink link:definitionLink 0000131 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Net Gains (Losses) Recorded in Accumulated Other Comprehensive Income (Loss) (Details) link:presentationLink link:calculationLink link:definitionLink 0000132 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Interest Rate Swaps Not Designated as Hedges (Details) link:presentationLink link:calculationLink link:definitionLink 0000133 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Interest Rate Swaps Recorded in Noninterest Expense (Details) link:presentationLink link:calculationLink link:definitionLink 0000134 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Risk Participation Agreement (Details) link:presentationLink link:calculationLink link:definitionLink 0000135 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Mortgage Banking Derivatives (Details) link:presentationLink link:calculationLink link:definitionLink 0000136 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Net Gains (Losses) Relating to Derivative Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 0000137 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of financial assets and financial liabilities measured at fair value on a recurring basis (Details) link:presentationLink link:calculationLink link:definitionLink 0000138 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of assets and liabilities measured at fair value on a non-recurring basis (Details) link:presentationLink link:calculationLink link:definitionLink 0000139 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of quantitative information about Level 3 fair value measurements (Details) link:presentationLink link:calculationLink link:definitionLink 0000140 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of estimated fair values of financial instruments (Details) link:presentationLink link:calculationLink link:definitionLink 0000141 - Disclosure - EARNINGS PER SHARE - Schedule of computation of earnings per common share (Details) link:presentationLink link:calculationLink link:definitionLink 0000142 - Disclosure - EARNINGS PER SHARE - Schedule of average shares excluded from computation of diluted earnings per common share (Details) link:presentationLink link:calculationLink link:definitionLink 0000143 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of changes in AOCI by component (Details) link:presentationLink link:calculationLink link:definitionLink 0000144 - Disclosure - OPERATING SEGMENTS AND RELATED INFORMATION (Details) link:presentationLink link:calculationLink link:definitionLink 0000145 - Disclosure - LEASES - Lease-related balances (Details) link:presentationLink link:calculationLink link:definitionLink 0000146 - Disclosure - LEASES - Lease Cost and Other Lease Information (Details) link:presentationLink link:calculationLink link:definitionLink 0000147 - Disclosure - LEASES - Undiscounted Lease Payments (Details) link:presentationLink link:calculationLink link:definitionLink 0000147 - Disclosure - LEASES - Undiscounted Lease Payments (Details) link:presentationLink link:calculationLink link:definitionLink 0000148 - Disclosure - LEASES - Busey as the Lessor (Details) link:presentationLink link:calculationLink link:definitionLink 0000149 - Disclosure - PARENT COMPANY ONLY FINANCIAL INFORMATION - Balance Sheets (Details) link:presentationLink link:calculationLink link:definitionLink 0000150 - Disclosure - PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Income (Details) link:presentationLink link:calculationLink link:definitionLink 0000151 - Disclosure - PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Cash Flows (Details) link:presentationLink link:calculationLink link:definitionLink