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LOANS AND ALLOWANCE FOR LOAN LOSSES - Troubled Debt Restructuring (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($) borrower	Sep. 30, 2021 USD ($) loan borrower	Sep. 30, 2020 USD ($) borrower
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	2	3	6	15
Pre-Modification Outstanding Recorded Investment	$ 502,000	$ 1,458,000	$ 6,596,000	$ 5,100,000
Post-Modification Outstanding Recorded Investment	502,000	1,458,000	6,596,000	5,100,000
Allowance for loan and lease losses, period increase (decrease)	200,000		1,900,000	100,000
Financing receivables, impaired, troubled debt restructuring, write-down	$ 0	$ 0	$ 0	$ 0
Commercial and agricultural: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	2	2	2	4
Pre-Modification Outstanding Recorded Investment	$ 502,000	$ 1,138,000	$ 502,000	$ 2,068,000
Post-Modification Outstanding Recorded Investment	$ 502,000	$ 1,138,000	$ 502,000	$ 2,068,000
Commercial and agricultural: | Commercial mortgages
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | borrower			2
Residential mortgages
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | borrower		1		4
Pre-Modification Outstanding Recorded Investment		$ 320,000		$ 997,000
Post-Modification Outstanding Recorded Investment		$ 320,000		$ 997,000
Commercial mortgages: | Commercial mortgages
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans			4	4
Pre-Modification Outstanding Recorded Investment			$ 6,094,000	$ 1,297,000
Post-Modification Outstanding Recorded Investment			$ 6,094,000	$ 1,297,000
Consumer loans: | Home equity lines and loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | borrower				3
Pre-Modification Outstanding Recorded Investment				$ 738,000
Post-Modification Outstanding Recorded Investment				$ 738,000

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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-Topic 310
-SubTopic 40
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