Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Maximum Subsidiary Dividend	$ 64,600
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	$ 330,657	$ 304,109
Total Capital (to Risk Weighted Assets) - Actual Ratio	14.80%	14.90%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 234,588	$ 202,059
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	10.50%	9.875%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 223,417	$ 204,100
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	$ 309,469	$ 283,913
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.80%	13.90%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 190,615	$ 161,361
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.50%	7.875%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 179,402	$ 163,403
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 309,469	$ 283,913
Tier One Leverage Capital to Average Assets	10.00%	9.60%
Tier One Leverage Capital Required for Capital Adequacy	$ 123,788	$ 118,297
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 154,735	$ 147,871
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 289,409	$ 263,863
Common Equity Tier 1 Capital Ratio Percentage	12.90%	12.90%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 157,044	$ 130,909
Common Equity Tier 1 Capital Ratio For Capital Adequacy	7.00%	6.375%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 145,826	$ 132,954
Common Equity Tier 1 Capital Ratio to be Well Capitalized	6.50%	6.50%
Glens Falls National
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	$ 254,438	$ 237,238
Total Capital (to Risk Weighted Assets) - Actual Ratio	14.50%	14.40%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 184,248	$ 163,101
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	10.50%	9.875%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 175,474	$ 164,749
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	$ 237,546	$ 220,844
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.50%	13.40%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 149,566	$ 130,199
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.50%	7.875%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 140,768	$ 131,847
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 237,546	$ 220,844
Tier One Leverage Capital to Average Assets	9.50%	9.10%
Tier One Leverage Capital Required for Capital Adequacy	$ 100,019	$ 97,074
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 125,024	$ 121,343
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 237,486	$ 220,794
Common Equity Tier 1 Capital Ratio Percentage	13.50%	13.40%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 123,141	$ 105,454
Common Equity Tier 1 Capital Ratio For Capital Adequacy	7.00%	6.375%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 114,345	$ 107,102
Common Equity Tier 1 Capital Ratio to be Well Capitalized	6.50%	6.50%
Saratoga National
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	$ 65,295	$ 56,483
Total Capital (to Risk Weighted Assets) - Actual Ratio	13.60%	14.20%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 50,412	$ 39,379
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	10.50%	9.875%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 48,011	$ 39,777
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	$ 60,999	$ 52,681
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	12.70%	13.20%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 40,826	$ 31,529
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	8.50%	7.875%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 38,425	$ 31,928
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 60,999	$ 52,681
Tier One Leverage Capital to Average Assets	9.60%	9.60%
Tier One Leverage Capital Required for Capital Adequacy	$ 25,416	$ 21,950
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 31,770	$ 27,438
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 60,999	$ 52,681
Common Equity Tier 1 Capital Ratio Percentage	12.70%	13.20%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 33,621	$ 25,542
Common Equity Tier 1 Capital Ratio For Capital Adequacy	7.00%	6.375%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 31,220	$ 25,941
Common Equity Tier 1 Capital Ratio to be Well Capitalized	6.50%	6.50%