Document and Entity Information Document - USD ($)
 12 Months Ended
Dec. 31, 2015
Feb. 29, 2016
Jun. 30, 2015
Entity Information [Line Items]      
Entity Registrant Name Arrow Financial Corporation    
Entity Central Index Key 0000717538    
Current Fiscal Year End Date --12-31    
Entity Filer Category Accelerated Filer    
Document Type 10-K    
Document Period End Date Dec. 31, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   12,952,227  
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float     $ 348,534,481