Business Combination - Schedule of Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands	Feb. 01, 2025	Feb. 01, 2025	Jun. 30, 2025	Jan. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Business Combination [Line Items]
Goodwill			$ 64,449		$ 44,185	$ 44,185	$ 44,185
Traditions Bancorp, Inc.
Business Combination [Line Items]
Business Combination, Consideration Transferred, Equity Interest		$ 83,649
Payments to Acquire Businesses, Gross		157
Business Combination, Consideration Transferred		83,806
Business Combination, Recognized Asset Acquired, Cash and Cash Equivalent	$ 36,363	36,363		$ 36,363
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investment Securities	97,666	97,666		98,484
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Investment Securities	(818)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loan Held-for-Sale	12,512	12,512		12,512
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans, Gross	648,462	648,462		673,805
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Loans, Gross	(25,343)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans, Allowance for Credit Losses	(1,464)	(1,464)		(4,045)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Loans, Allowance for Credit Losses	2,581
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans, Net	646,998	646,998		669,760
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Loans, Net	(22,762)
Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment, Equipment	6,873	6,873		7,235
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Equipment	(362)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Right of Use Asset	2,932	2,932		2,932
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restricted Investment in Bank Stocks	3,323	3,323		3,323
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investment in Bank-Owned Life Insurance	16,384	16,384		16,384
Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Finite-Lived	18,854	18,854		0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles	18,854
Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent	15,545	15,545		14,147
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Noncurrent Assets	1,398
Business Combination, Recognized Asset Acquired, Asset	857,450	857,450		861,140
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Assets	(3,690)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	741,508	741,508		741,723
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deposits	(215)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Borrowings	188
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Borrowings	40,188	40,188		40,000
Business Combination, Recognized Liability Assumed, Lease Obligation	3,125	3,125		3,125
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Allowance for Unfunded Commitments	970	970		118
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Allowance For Unfunded Commitments	852
Business Combination, Recognized Liability Assumed, Other Liability, Noncurrent	8,117	8,117		8,158
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Noncurrent Liabilities, Other	(41)
Business Combination, Recognized Liability Assumed, Liability	793,908	793,908		793,124
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Liabilities	784
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred	(4,474)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	63,542	63,542		$ 68,016
Goodwill	$ 20,264	$ 20,264

ACNB CORP 10-Q