XML 53 R1.htm IDEA: XBRL DOCUMENT v3.19.3
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2019
Oct. 31, 2019
Document and Entity Information [Abstract]    
Entity Registrant Name Arrow Financial Corporation  
Entity Central Index Key 0000717538  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Emerging Growth Company false  
Entity Small Business false  
Document Type 10-Q  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding (in shares)   14,976,493
Entity Current Reporting Status Yes