XML 12 R1.htm IDEA: XBRL DOCUMENT v3.20.2
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2020
Jul. 31, 2020
Document and Entity Information [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2020  
Document Transition Report false  
Entity File Number 1-35015  
Entity Registrant Name ACNB CORP  
Entity Incorporation, State or Country Code PA  
Entity Tax Identification Number 23-2233457  
Entity Address, Address Line One 16 Lincoln Square,  
Entity Address, City or Town Gettysburg,  
Entity Address, State or Province PA  
Entity Address, Postal Zip Code 17325  
City Area Code 717  
Local Phone Number 334-3161  
Title of 12(b) Security Common Stock, $2.50 par value per share  
Trading Symbol ACNB  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Document Shell Company Report false  
Entity Common Stock, Shares Outstanding   8,695,839
Entity Central Index Key 0000715579  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q2  
Amendment Flag false