Basis of Presentation and Nature of Operations	3 Months Ended
Basis of Presentation and Nature of Operations	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Nature of Operations	Basis of Presentation and Nature of Operations ACNB Corporation, headquartered in Gettysburg, Pennsylvania, provides banking, insurance, and financial services to businesses and consumers through its wholly-owned subsidiaries, ACNB Bank and ACNB Insurance Services. The Bank engages in full-service commercial and consumer banking and wealth management services, including trust and retail brokerage, through its 26 community banking offices, including 17 community banking office locations in Adams, Cumberland, Franklin and York Counties, Pennsylvania, and nine community banking office locations in Carroll and Frederick Counties, Maryland. There are also loan production offices in Lancaster and York, Pennsylvania, and Hunt Valley, Maryland. ACNB Insurance Services is a full-service insurance agency based in Westminster, Maryland, with additional locations in Jarrettsville, Maryland, and Gettysburg, Pennsylvania. The agency offers a broad range of property, casualty, health, life and disability insurance to both individual and commercial clients. The accompanying unaudited Consolidated Financial Statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities as of the date of the financial statements as well as revenues and expenses during the period. Actual results could differ from those estimates. In the opinion of management, the accompanying unaudited Consolidated Financial Statements contain all adjustments necessary for a fair presentation. All such adjustments are of a normal recurring nature. These Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the notes included in the Corporation’s Annual Report on Form 10-K for the year ended December 31, 2023. The Corporation evaluates subsequent events through the filing date of this From 10-Q with the SEC. The results of operations for the three month period ended March 31, 2024, are not necessarily indicative of the results to be expected for the full year. Certain reclassifications have been made to the prior period financial statements to conform to the current period presentation. Reclassifications had no material effect on prior year net income or stockholders’ equity. Significant Accounting Policies The significant accounting policies used in preparation of the Consolidated Financial Statements are disclosed in the Corporation’s 2023 Annual Report on Form 10-K. Those significant accounting policies are unchanged at March 31, 2024. Recently Issued Accounting Standards In December 2022, the FASB issued ASU 2022-06, “Deferral of the Sunset Date of Reference Rate Reform (Topic 848)”. This ASU extends the sunset date of ASC Topic 848 (Reference Rate Reform) to December 31, 2024, in response to the United Kingdom’s FCA extension of the intended cessation date of LIBOR in the United States. The Corporation evaluated the impact of this standard, and believes that its adoption will not have a material impact on the Corporation’s Consolidated Financial Statements. In November 2023, the FASB issued ASU 2023-07, “Segment Reporting (Topic 280)”. The amendments in this ASU are expected to improve financial reporting by requiring disclosure of incremental segment information on an annual and interim basis for all public entities to enable investors to develop more decision-useful financial analyses. The amendments of ASU 2023-07 are effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The amendments in ASU 2023-07 should be applied retrospectively to all periods presented on the financial statements. The Corporation adopted the amendments of ASU 2023-07 related to annual disclosure requirements effective January 1, 2024, and will present any newly required annual disclosures in its Annual Report on Form 10-K for the year ending December 31, 2024 and intends to adopt the amendments of ASU 2023-07 related to interim disclosure requirements effective January 1, 2025, and will present any newly required interim disclosures beginning with its Quarterly Report on Form 10-Q for the period ending March 31, 2025. Adoption of this standard is not expected to have a material impact on the Corporation’s Consolidated Financial Statements. In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740)”. This ASU is intended to improve the disclosures for income taxes to address requests from investors, lenders, creditors and other allocators of capital that use the financial statements to make capital allocation decisions. The amendments in ASU 2023-09 will require consistent categories and greater disaggregation of information in the rate reconciliation disclosure as well as disclosure of income taxes paid disaggregated by jurisdiction. The amendments of ASU 2023-09 are effective for annual periods beginning after December 15, 2024, and early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The Corporation intends to adopt the amendments of ASU 2023-09 effective January 1, 2025, and will include the required disclosures in its Annual Report on Form 10-K for the year ending December 31, 2025. The Corporation is currently evaluating the impact of this standard, and believes that its adoption will not have a material impact on the Corporation’s Consolidated Financial Statements.