ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 35,752	$ 27,834
Gain on sale of low-income housing partnership	(421)	0
Net Cash Provided by Operating Activities	39,201	42,126
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from sale of low-income housing partnerships	421	0
Proceeds from sales of equity securities	811	0
Net Cash (Used in) Provided by Investing Activities	(331,723)	60,521
CASH FLOWS USED IN FINANCING ACTIVITIES
Proceeds from long-term borrowings	1,500	15,000
Repayments on long-term debt	(15,200)	(34,045)
Common stock repurchased	(6,682)	(1,517)
Proceeds from issuance of common stock	713	60
Dividends paid	(9,117)	(8,968)
Net Cash (Used in) Provided by Financing Activities	(249,448)	208,132
Net (Decrease) Increase in Cash and Cash Equivalents	(541,970)	310,779
CASH AND CASH EQUIVALENTS — BEGINNING	710,131	399,352
CASH AND CASH EQUIVALENTS — ENDING	168,161	710,131
Corporation
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	35,752	27,834
Equity in undistributed earnings of subsidiaries	(27,240)	(19,450)
(Increase) Decrease in receivable from banking subsidiary	(311)	54
Gain on sale of securities	(13)	0
Net (losses) gains on equity securities	(177)	468
Gain on sale of low-income housing partnership	(421)	0
Other	(308)	555
Net Cash Provided by Operating Activities	7,636	8,525
CASH FLOWS FROM INVESTING ACTIVITIES
Return on investment from subsidiary	13,000	0
Proceeds from sale of low-income housing partnerships	421	0
Proceeds from sales of equity securities	811	0
Net Cash (Used in) Provided by Investing Activities	14,232	0
CASH FLOWS USED IN FINANCING ACTIVITIES
Proceeds from long-term borrowings	0	15,000
Repayments on long-term debt	(2,700)	(6,329)
Common stock repurchased	(6,681)	(1,517)
Proceeds from issuance of common stock	1,442	343
Dividends paid	(9,117)	(8,968)
Net Cash (Used in) Provided by Financing Activities	(17,056)	(1,471)
Net (Decrease) Increase in Cash and Cash Equivalents	4,812	7,054
CASH AND CASH EQUIVALENTS — BEGINNING	13,451	6,397
CASH AND CASH EQUIVALENTS — ENDING	$ 18,263	$ 13,451