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ACQUISITIONS, Intangible Asset, Goodwill and Acquisition-related Expenses (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 12, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value of Subordinated Notes Payable [Abstract]
Subordinated notes payable		$ 13,755		$ 13,755		$ 13,795
Summary of loans acquired [Abstract]
Acquisition-related expenses		3,372	$ 1,194	$ 3,741	$ 1,728
Subordinated Notes Maturing in February 2028 [Member]
Fair Value of Subordinated Notes Payable [Abstract]
Subordinated notes payable	$ 3,000
Fixed interest rate percentage	6.00%
Maturity date	Feb. 29, 2028
Subordinated Notes Maturing in November 2025 [Member]
Fair Value of Subordinated Notes Payable [Abstract]
Subordinated notes payable	$ 10,000
Fixed interest rate percentage	6.375%
Maturity date	Nov. 30, 2025
Kinderhook Bank Corp [Member] \| Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life				8 years
Kinderhook Bank Corp [Member] \| Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life				8 years
Steuben [Member]
Summary of loans acquired [Abstract]
Acquisition-related expenses		$ 3,300		$ 3,600
Steuben [Member] \| Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life				8 years
Steuben [Member] \| Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life				8 years