Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2011
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	ACCOUNTING POLICIES In the opinion of the management of Arrow Financial Corporation (Arrow), the accompanying unaudited consolidated interim financial statements contain all of the adjustments necessary to present fairly the financial position as of March 31, 2012, December 31, 2011 and March 31, 2011; the results of operations for three-month periods ended March 31, 2012 and 2011; the consolidated statements of comprehensive income for the three-month periods ended March 31, 2012 and 2011; the changes in stockholders' equity for the three-month periods ended March 31, 2012 and 2011; and the cash flows for the three-month periods ended March 31, 2012 and 2011. All such adjustments are of a normal recurring nature. The preparation of financial statements requires the use of management estimates. The unaudited consolidated interim financial statements should be read in conjunction with the audited annual consolidated financial statements of Arrow for the year ended December 31, 2011, included in Arrow's 2011 Form 10-K.

The entire disclosure for all significant accounting policies of the reporting entity.