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LOANS AND ALLOWANCE FOR LOAN LOSSES - Allowances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Dec. 31, 2020
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	$ 20,924	$ 23,478
Charge-offs	(190)	(433)
Recoveries	434	140
Net recoveries (charge-offs)	244	(293)
Provision	(259)	3,050
Ending balance	20,909	26,235
Ending allowance balance attributable to loans:
Individually evaluated for impairment			$ 1,579	$ 1,527
Collectively evaluated for impairment			19,330	19,397
Total ending allowance balance	20,924	26,235	20,909	20,924
Loans:
Loans individually evaluated for impairment			9,922	10,589
Loans collectively evaluated for  impairment			1,576,062	1,530,909
Total ending loans balance			1,585,984	1,541,498
Commercial and Agricultural
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	4,493	10,227
Charge-offs	0	(30)
Recoveries	296	4
Net recoveries (charge-offs)	296	(26)
Provision	(452)	990
Ending balance	4,337	11,191
Ending allowance balance attributable to loans:
Individually evaluated for impairment			1,430	1,401
Collectively evaluated for impairment			2,907	3,092
Total ending allowance balance	4,337	11,191	4,337	4,493
Loans:
Loans individually evaluated for impairment			3,378	3,400
Loans collectively evaluated for  impairment			397,341	366,852
Total ending loans balance			400,719	370,252
Commercial mortgages:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	11,496	8,869
Charge-offs	0	0
Recoveries	0	1
Net recoveries (charge-offs)	0	1
Provision	290	1,603
Ending balance	11,786	10,473
Ending allowance balance attributable to loans:
Individually evaluated for impairment			107	74
Collectively evaluated for impairment			11,679	11,422
Total ending allowance balance	11,496	10,473	11,786	11,496
Loans:
Loans individually evaluated for impairment			5,223	5,117
Loans collectively evaluated for  impairment			726,215	714,028
Total ending loans balance			731,438	719,145
Residential mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	2,079	1,252
Charge-offs	(26)	0
Recoveries	0	0
Net recoveries (charge-offs)	(26)	0
Provision	62	169
Ending balance	2,115	1,421
Ending allowance balance attributable to loans:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			2,115	2,079
Total ending allowance balance	2,079	1,421	2,115	2,079
Loans:
Loans individually evaluated for impairment			964	1,271
Loans collectively evaluated for  impairment			244,879	238,742
Total ending loans balance			245,843	240,013
Consumer loans:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	2,856	3,130
Charge-offs	(164)	(403)
Recoveries	138	135
Net recoveries (charge-offs)	(26)	(268)
Provision	(159)	288
Ending balance	2,671	3,150
Ending allowance balance attributable to loans:
Individually evaluated for impairment			42	52
Collectively evaluated for impairment			2,629	2,804
Total ending allowance balance	$ 2,671	$ 3,150	2,671	2,856
Loans:
Loans individually evaluated for impairment			357	801
Loans collectively evaluated for  impairment			207,627	211,287
Total ending loans balance			$ 207,984	$ 212,088

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