Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2023
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations First Busey Corporation, a Nevada corporation organized in 1980, is a $12.2 billion financial holding company headquartered in Champaign, Illinois. Busey’s common stock is traded on The Nasdaq Global Select Market under the symbol “BUSE.” First Busey operates and reports its business in three segments: Banking, FirsTech, and Wealth Management. •The Banking operating segment provides a full range of banking services to individual and corporate customers through its banking center network in Illinois; the St. Louis, Missouri metropolitan area; southwest Florida; and Indianapolis, Indiana. •The FirsTech operating segment provides comprehensive and innovative payment technology solutions including online, mobile, and voice-recognition bill payments; money management and credit card networks; direct debit services; lockbox remittance processing for payments made by mail; and walk-in payments. FirsTech also provides additional tools to help clients with billing, reconciliation, bill reminders, and treasury services. •The Wealth Management operating segment provides a full range of asset management, investment, brokerage, fiduciary, philanthropic advisory, tax preparation, and farm management services to individuals, businesses, and foundations. For additional information about First Busey's operating segments, see “Note 14. Operating Segments and Related Information.”
Basis of Financial Statement Presentation	Basis of Financial Statement Presentation These unaudited consolidated financial statements and related notes should be read in conjunction with the audited consolidated financial statements included in Busey's 2022 Annual Report. These interim unaudited consolidated financial statements serve to update our 2022 Annual Report and may not include all information and notes necessary to constitute a complete set of financial statements. We prepared these unaudited consolidated financial statements in conformity with GAAP. We have eliminated intercompany accounts and transactions. We have also reclassified certain prior year amounts to conform to the current period presentation. These reclassifications did not have a material impact on our consolidated financial condition or results of operations. In our opinion, the unaudited consolidated financial statements reflect all normal, recurring adjustments needed to present fairly our results for the interim periods. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.
Use of Estimates	Use of Estimates In preparing the accompanying unaudited consolidated financial statements in conformity with GAAP, Busey’s management is required to make estimates and assumptions that affect the amounts reported in the financial statements and the disclosures provided. Actual results could differ from those estimates. Material estimates which are particularly susceptible to significant change in the near term relate to the fair value of debt securities available for sale, fair value of assets acquired and liabilities assumed in business combinations, goodwill, income taxes, and the determination of the ACL.
Impact of Recently Adopted Accounting Standards	Impact of Recently Adopted Accounting Standards In March 2022, the FASB issued ASU 2022-02 “Financial Instruments—Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures,” which eliminates the TDR accounting model for creditors that have already adopted CECL. In lieu of the TDR accounting model, loan refinancing and restructuring guidance in ASC Subtopic 310-20-35-9 through 35-11 “Receivables—Nonrefundable Fees and Other Costs—Subsequent Measurement—Loan Refinancing or Restructuring” will apply to all loan modifications, including those made for borrowers experiencing financial difficulty. This standard also enhances disclosure requirements related to certain loan modifications. Additionally, this standard introduces new requirements to disclose gross write-off information in the vintage disclosures of financing receivables by credit quality indicator and class of financing receivable by year of origination. This standard applies prospectively. For the transition method related to the recognition and measurement of TDRs, there is an option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. This standard became effective for Busey beginning January 1, 2023. Adoption of this standard did not have a material impact on Busey’s financial position or results of operations. In March 2022, the FASB issued ASU 2022-01 “Derivatives and Hedging (Topic 815): Fair Value Hedging—Portfolio Layer Method,” which replaces the current last-of-layer hedge accounting method with an expanded portfolio layer method that permits multiple hedged layers of a single closed portfolio. The scope of the portfolio layer method is also expanded to include non-prepayable financial assets. This update also provides additional guidance on the accounting for and disclosure of hedge basis adjustments that are applicable to the portfolio layer method, and specifies how hedge basis adjustments should be considered when determining credit losses for the assets included in the closed portfolio. Amendments related to hedge basis adjustments which are included in this standard apply on a modified retrospective basis by means of a cumulative-effect adjustment to the opening balance of retained earnings on the initial application date. Amendments related to disclosure which are included in this standard may be applied on a prospective basis from the initial application date, or on a retrospective basis to each prior period presented after the date of adoption of the amendments in ASU 2017-12 “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” This standard became effective for Busey beginning January 1, 2023. Adoption of this standard did not have a material impact on Busey’s financial position or results of operations. ASU 2021-08 “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers” requires measurement and recognition in accordance with ASC Topic 606 “Revenue from Contracts with Customers” for contract assets and contract liabilities acquired in a business combination. This update became effective for Busey beginning January 1, 2023. This standard applies prospectively to all business combinations that occur on or after the date it is adopted. Adoption of this standard did not have an impact on Busey’s financial position or results of operations. Recently Issued Accounting Standards Not Yet Adopted In March 2023, the FASB issued ASU 2023-02 “Investments—Equity Method and Joint Ventures (Topic 323),” permitting an election to use the proportional amortization method to account for equity investments made primarily for the purpose of receiving income tax credits and other income tax benefits, regardless of the tax credit program from which the income tax credits are received, provided that certain conditions are met. The proportional amortization method results in the cost of the investment being amortized in proportion to the income tax credits and other income tax benefits received, with the amortization of the investment and the income tax credits being presented net in the income statement as a component of income tax expense. This standard must be applied on a retrospective or modified retrospective basis, and is applicable for Busey beginning on January 1, 2024. Early adoption is permitted. Busey is currently evaluating the potential effect on the Company’s financial position and results of operations, and upon adoption expects changes to be reflected in the Other Expense and Income Taxes line items in the Consolidated Statements of Income. In March 2023, the FASB issued ASU 2023-01 “Leases (Topic 842): Common Control Arrangements,” which requires amortization over the useful life of leasehold improvements (not the lease term) when the lease is between entities under common control, and any value of such leasehold improvements remaining at the end of the lease term is to be accounted for as a transfer between entities under common control. This standard may be adopted either prospectively, or retrospectively, and is effective for Busey beginning January 1, 2024. Early adoption is permitted. Busey is currently evaluating the potential effect on the Company’s financial position and results of operations. In June 2022, the FASB issued ASU 2022-03 “Fair Value Measurements (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions,” which clarifies that contractual restrictions on the sale of equity securities are not considered in measuring the fair value of those equity securities, and further that contractual sale restrictions cannot be recognized and measured as a separate unit of account. This standard applies prospectively, and is effective for Busey beginning January 1, 2024. Early adoption is permitted. Busey is currently evaluating the potential effect on the Company’s financial position and results of operations.
Subsequent Events	Subsequent Events Busey has evaluated subsequent events for potential recognition and/or disclosure through the date the unaudited consolidated financial statements included in this Quarterly Report were issued. There were no significant subsequent events for the quarter ended June 30, 2023, through the filing date of these unaudited consolidated financial statements.