Regulatory Matters (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Maximum Subsidiary Dividend	$ 71,800
Parent Company
Actual, Amount
Total Capital (to Risk Weighted Assets)	364,988	$ 330,657
Tier I Capital (to Risk Weighted Assets)	335,756	309,469
Tier One Capital (to Average Assets)	335,756	309,469
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 315,696	$ 289,409
Actual, Ratio
Total Capital (to Risk Weighted Assets)	0.155	0.148
Tier I Capital (to Risk Weighted Assets)	0.142	0.138
Tier One Leverage Capital (to Average Assets)	0.091	0.100
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.134	0.129
Minimum Amounts For Capital Adequacy, Amount
Total Capital (to Risk Weighted Assets)	$ 247,250	$ 234,588
Tier I Capital (to Risk Weighted Assets)	200,981	190,615
Tier One Leverage Capital (to Average Assets)	147,585	123,788
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 164,916	$ 157,044
Minimum Amounts For Capital Adequacy Purposes, Ratio
Total Capital (to Risk Weighted Assets)	0.105	0.105
Tier I Capital (to Risk Weighted Assets)	0.085	0.085
Tier One Leverage Capital (to Average Assets)	0.040	0.040
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.070	0.070
Minimum Amounts To Be Well-Capitalized, Amount
Total Capital (to Risk Weighted Assets)	$ 235,476	$ 223,417
Tier I Capital (to Risk Weighted Assets)	189,158	179,402
Tier One Leverage Capital (to Average Assets)	184,481	154,735
Common Equity Tier 1 Leverage Capital (to Risk Weighted Assets)	$ 153,136	$ 145,826
Minimum Amounts To Be Well-Capitalized
Total Capital (to Risk Weighted Assets)	0.100	0.100
Tier One Risk Based Capital (to Risk Weighted Assets)	0.080	0.080
Tier One Leverage Capital (to Average Assets)	0.050	0.050
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.065	0.065
Glens Falls National
Actual, Amount
Total Capital (to Risk Weighted Assets)	$ 273,801	$ 254,438
Tier I Capital (to Risk Weighted Assets)	251,419	237,546
Tier One Capital (to Average Assets)	251,419	237,546
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 251,359	$ 237,486
Actual, Ratio
Total Capital (to Risk Weighted Assets)	0.152	0.145
Tier I Capital (to Risk Weighted Assets)	0.139	0.135
Tier One Leverage Capital (to Average Assets)	0.087	0.095
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.139	0.135
Minimum Amounts For Capital Adequacy, Amount
Total Capital (to Risk Weighted Assets)	$ 189,139	$ 184,248
Tier I Capital (to Risk Weighted Assets)	153,745	149,566
Tier One Leverage Capital (to Average Assets)	115,595	100,019
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 126,584	$ 123,141
Minimum Amounts For Capital Adequacy Purposes, Ratio
Total Capital (to Risk Weighted Assets)	0.105	0.105
Tier I Capital (to Risk Weighted Assets)	0.085	0.085
Tier One Leverage Capital (to Average Assets)	0.040	0.040
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.070	0.070
Minimum Amounts To Be Well-Capitalized, Amount
Total Capital (to Risk Weighted Assets)	$ 180,132	$ 175,474
Tier I Capital (to Risk Weighted Assets)	144,702	140,768
Tier One Leverage Capital (to Average Assets)	144,494	125,024
Common Equity Tier 1 Leverage Capital (to Risk Weighted Assets)	$ 117,542	$ 114,345
Minimum Amounts To Be Well-Capitalized
Total Capital (to Risk Weighted Assets)	0.100	0.100
Tier One Risk Based Capital (to Risk Weighted Assets)	0.080	0.080
Tier One Leverage Capital (to Average Assets)	0.050	0.050
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.065	0.065
Saratoga National
Actual, Amount
Total Capital (to Risk Weighted Assets)	$ 78,022	$ 65,295
Tier I Capital (to Risk Weighted Assets)	71,172	60,999
Tier One Capital (to Average Assets)	71,172	60,999
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 71,172	$ 60,999
Actual, Ratio
Total Capital (to Risk Weighted Assets)	0.142	0.136
Tier I Capital (to Risk Weighted Assets)	0.130	0.127
Tier One Leverage Capital (to Average Assets)	0.089	0.096
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.130	0.127
Minimum Amounts For Capital Adequacy, Amount
Total Capital (to Risk Weighted Assets)	$ 57,692	$ 50,412
Tier I Capital (to Risk Weighted Assets)	46,536	40,826
Tier One Leverage Capital (to Average Assets)	31,987	25,416
Common Equity Tier 1 Capital (to Risk Weighted Assets)	$ 38,323	$ 33,621
Minimum Amounts For Capital Adequacy Purposes, Ratio
Total Capital (to Risk Weighted Assets)	0.105	0.105
Tier I Capital (to Risk Weighted Assets)	0.085	0.085
Tier One Leverage Capital (to Average Assets)	0.040	0.040
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.070	0.070
Minimum Amounts To Be Well-Capitalized, Amount
Total Capital (to Risk Weighted Assets)	$ 54,945	$ 48,011
Tier I Capital (to Risk Weighted Assets)	43,798	38,425
Tier One Leverage Capital (to Average Assets)	39,984	31,770
Common Equity Tier 1 Leverage Capital (to Risk Weighted Assets)	$ 35,586	$ 31,220
Minimum Amounts To Be Well-Capitalized
Total Capital (to Risk Weighted Assets)	0.100	0.100
Tier One Risk Based Capital (to Risk Weighted Assets)	0.080	0.080
Tier One Leverage Capital (to Average Assets)	0.050	0.050
Common Equity Tier 1 Capital (to Risk Weighted Assets)	0.065	0.065