Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011
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, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding	11,892,843
Entity Well-known Seasoned Filer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 275,731,916