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LOANS AND ALLOWANCE FOR LOAN LOSSES - Allowances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	$ 20,676	$ 24,130	$ 20,924	$ 23,478
Charge-offs	(234)	(326)	(650)	(3,248)
Recoveries	142	107	719	371
Net recoveries (charge-offs)	(92)	(219)	69	(2,877)
Provision	356	679	(53)	3,989
Ending balance	20,940	24,590	20,940	24,590
Ending allowance balance attributable to loans:
Individually evaluated for impairment	3,398		3,398		$ 1,527
Collectively evaluated for impairment	17,542		17,542		19,397
Total ending allowance balance	20,940	24,590	20,940	24,590	20,924
Loans:
Loans individually evaluated for impairment	12,217		12,217		10,589
Loans collectively evaluated for  impairment	1,508,712		1,508,712		1,530,909
Total ending loans balance	1,520,929		1,520,929		1,541,498
Commercial and agricultural:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	3,628	8,327	4,493	10,227
Charge-offs	0	(68)	(25)	(134)
Recoveries	8	18	283	27
Net recoveries (charge-offs)	8	(50)	258	(107)
Provision	(15)	180	(1,130)	(1,663)
Ending balance	3,621	8,457	3,621	8,457
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,525		1,525		1,401
Collectively evaluated for impairment	2,096		2,096		3,092
Total ending allowance balance	3,621	8,457	3,621	8,457	4,493
Loans:
Loans individually evaluated for impairment	2,582		2,582		3,400
Loans collectively evaluated for  impairment	269,290		269,290		366,852
Total ending loans balance	271,872		271,872		370,252
Commercial mortgages:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	12,963	10,549	11,496	8,869
Charge-offs	(44)	0	(44)	(2,143)
Recoveries	1	2	2	2
Net recoveries (charge-offs)	(43)	2	(42)	(2,141)
Provision	361	361	1,827	4,184
Ending balance	13,281	10,912	13,281	10,912
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,800		1,800		74
Collectively evaluated for impairment	11,481		11,481		11,422
Total ending allowance balance	13,281	10,912	13,281	10,912	11,496
Loans:
Loans individually evaluated for impairment	8,356		8,356		5,117
Loans collectively evaluated for  impairment	783,120		783,120		714,028
Total ending loans balance	791,476		791,476		719,145
Residential mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	1,791	1,891	2,079	1,252
Charge-offs	0	(42)	(71)	(56)
Recoveries	0	0	10	49
Net recoveries (charge-offs)	0	(42)	(61)	(7)
Provision	80	232	(147)	836
Ending balance	1,871	2,081	1,871	2,081
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0		0
Collectively evaluated for impairment	1,871		1,871		2,079
Total ending allowance balance	1,871	2,081	1,871	2,081	2,079
Loans:
Loans individually evaluated for impairment	946		946		1,271
Loans collectively evaluated for  impairment	253,695		253,695		238,742
Total ending loans balance	254,641		254,641		240,013
Consumer loans:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	2,294	3,363	2,856	3,130
Charge-offs	(190)	(216)	(510)	(915)
Recoveries	133	87	424	293
Net recoveries (charge-offs)	(57)	(129)	(86)	(622)
Provision	(70)	(94)	(603)	632
Ending balance	2,167	3,140	2,167	3,140
Ending allowance balance attributable to loans:
Individually evaluated for impairment	73		73		52
Collectively evaluated for impairment	2,094		2,094		2,804
Total ending allowance balance	2,167	$ 3,140	2,167	$ 3,140	2,856
Loans:
Loans individually evaluated for impairment	333		333		801
Loans collectively evaluated for  impairment	202,607		202,607		211,287
Total ending loans balance	$ 202,940		$ 202,940		$ 212,088

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