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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 |  |

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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e1043-128460 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)(a)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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