Regulatory Matters (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Arrow Financial Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	$ 200,480	$ 187,681
Total Capital (to Risk Weighted Assets) - Actual Ratio	16.30%	16.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	98,395	93,841
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.00%	8.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	122,994	117,301
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	10.00%	10.00%
Tier I Capital (to Risk Weighted Assets) - Actual Amount	185,170	172,956
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	15.00%	14.70%
Tier I Capital (to Risk Weighted Assets) - Minimum Acounts For Capital Adequacy Purposes Amount	49,379	47,063
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	74,068	70,594
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	6.00%	6.00%
Tier I Capital (to Average Assets) - Actual Amount	185,170	172,956
Tier I Capital (to Average Assets) - Actual Ratio	9.10%	9.00%
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	81,393	76,869
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Amount	81,393	76,869
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Ratio	4.00%	4.00%
Glens Falls National [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	164,889	155,209
Total Capital (to Risk Weighted Assets) - Actual Ratio	16.20%	15.90%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	81,427	78,093
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.00%	8.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	101,783	97,616
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	10.00%	10.00%
Tier I Capital (to Risk Weighted Assets) - Actual Amount	152,205	142,998
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	14.90%	14.60%
Tier I Capital (to Risk Weighted Assets) - Minimum Acounts For Capital Adequacy Purposes Amount	40,860	39,178
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	61,291	58,766
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	6.00%	6.00%
Tier I Capital (to Average Assets) - Actual Amount	152,205	142,998
Tier I Capital (to Average Assets) - Actual Ratio	8.80%	8.60%
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	69,184	66,511
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Amount	86,480	83,138
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Ratio	5.00%	5.00%
Saratoga National [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	31,911	29,853
Total Capital (to Risk Weighted Assets) - Actual Ratio	15.10%	15.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	16,906	15,922
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.00%	8.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	21,133	19,902
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	10.00%	10.00%
Tier I Capital (to Risk Weighted Assets) - Actual Amount	29,297	27,365
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.80%	13.80%
Tier I Capital (to Risk Weighted Assets) - Minimum Acounts For Capital Adequacy Purposes Amount	8,492	7,932
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	12,738	11,898
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	6.00%	6.00%
Tier I Capital (to Average Assets) - Actual Amount	29,297	27,365
Tier I Capital (to Average Assets) - Actual Ratio	9.40%	9.30%
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	12,467	11,770
Tier I Capital (to Average Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 15,584	$ 14,712
Tier I Capital (to Average Assets) - Minimum Amounts To Be Well-Capitalized Ratio	5.00%	5.00%