Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Maximum Subsidiary Dividend	$ 56,100
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk Weighted Assets) - Actual Amount	$ 304,109	$ 278,163
Total Capital (to Risk Weighted Assets) - Actual Ratio	14.90%	15.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 202,059	$ 172,461
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	9.90%	9.30%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 204,100	$ 185,442
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	$ 283,913	$ 259,378
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.90%	14.00%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 161,361	$ 135,247
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	7.90%	7.30%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 163,403	$ 148,216
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 283,913	$ 259,378
Tier One Leverage Capital to Average Assets	9.60%	9.50%
Tier One Leverage Capital Required for Capital Adequacy	$ 118,297	$ 109,212
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 147,871	$ 136,515
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 263,863	$ 239,326
Common Equity Tier 1 Capital Ratio Percentage	12.90%	12.90%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 130,909	$ 107,604
Common Equity Tier 1 Capital Ratio For Capital Adequacy	6.40%	5.80%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 132,954	$ 120,591
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	$ 237,238	$ 220,275
Total Capital (to Risk Weighted Assets) - Actual Ratio	14.40%	14.60%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 163,101	$ 140,312
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	9.90%	9.30%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 164,749	$ 150,873
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	$ 220,844	$ 205,200
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.40%	13.60%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 130,199	$ 110,144
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	7.90%	7.30%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 131,847	$ 120,706
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 220,844	$ 205,200
Tier One Leverage Capital to Average Assets	9.10%	9.10%
Tier One Leverage Capital Required for Capital Adequacy	$ 97,074	$ 90,198
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 121,343	$ 112,747
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 220,794	$ 205,148
Common Equity Tier 1 Capital Ratio Percentage	13.40%	13.60%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 105,454	$ 87,490
Common Equity Tier 1 Capital Ratio For Capital Adequacy	6.40%	5.80%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 107,102	$ 98,049
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	$ 56,483	$ 48,822
Total Capital (to Risk Weighted Assets) - Actual Ratio	14.20%	14.00%
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Amount	$ 39,379	$ 32,432
Total Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	9.90%	9.30%
Total Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Amount	$ 39,777	$ 34,873
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	$ 52,681	$ 45,311
Tier I Capital (to Risk Weighted Assets) - Actual Ratio	13.20%	13.00%
Tier I Capital (to Risk Weighted Assets) - Minimum Accounts For Capital Adequacy Purposes Amount	$ 31,529	$ 25,444
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts For Capital Adequacy Purposes Ratio	7.90%	7.30%
Tier I Capital (to Risk Weighted Assets) - Minimum Amounts To Be Well-Capitalized Ratio	$ 31,928	$ 27,884
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 52,681	$ 45,311
Tier One Leverage Capital to Average Assets	9.60%	9.40%
Tier One Leverage Capital Required for Capital Adequacy	$ 21,950	$ 19,281
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 27,438	$ 24,102
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Common Equity Tier 1 Capital Ratio	$ 52,681	$ 45,311
Common Equity Tier 1 Capital Ratio Percentage	13.20%	13.00%
Common Equity Tier 1 Capital Ratio Required for Capital Adequacy	$ 25,542	$ 20,216
Common Equity Tier 1 Capital Ratio For Capital Adequacy	6.40%	5.80%
Common Equity Tier 1 Leverage Capital Required to be Well Capitalized	$ 25,941	$ 22,656
Common Equity Tier 1 Capital Ratio to be Well Capitalized	6.50%	6.50%