LOANS HELD FOR INVESTMENT AND ALLOWANCE FOR CREDIT LOSSES (Activity in the allowance for credit losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Activity in the allowance for loan losses by portfolio class
Beginning Balance		$ 14,593		$ 14,210
Provision for Credit Losses		776		2,189
Charge-Offs		(1,659)		(3,885)
Recoveries		609		1,805
Net Charge-Offs		(1,050)		(2,080)
Ending Balance		14,319		14,319
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 22,457		$ 13,905
Provision for credit losses	1,265		7,870
Charge-Offs	(1,282)		(4,776)
Recoveries	697		2,869
Net loan charge-offs	(585)		(1,907)
Ending Balance	23,137		23,137
Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			3,269
Commercial, Financial and Agricultural [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		1,648		1,434
Provision for Credit Losses		236		648
Charge-Offs		(289)		(619)
Recoveries		86		218
Net Charge-Offs		(203)		(401)
Ending Balance		1,681		1,681
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,468		1,675
Provision for credit losses	(195)		544
Charge-Offs	(137)		(685)
Recoveries	74		188
Net loan charge-offs	(63)		(497)
Ending Balance	2,210		2,210
Commercial, Financial and Agricultural [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			488
Real Estate - Construction [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		521		280
Provision for Credit Losses		81		322
Charge-Offs		(223)		(223)
Recoveries		0		0
Net Charge-Offs		(223)		(223)
Ending Balance		379		379
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	1,955		370
Provision for credit losses	161		1,444
Charge-Offs	0		0
Recoveries	0		0
Net loan charge-offs	0		0
Ending Balance	2,116		2,116
Real Estate - Construction [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			302
Real Estate - Commercial Mortgage [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		3,889		4,181
Provision for Credit Losses		(304)		(611)
Charge-Offs		(26)		(181)
Recoveries		142		312
Net Charge-Offs		116		131
Ending Balance		3,701		3,701
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	6,640		3,416
Provision for credit losses	616		2,132
Charge-Offs	(17)		(28)
Recoveries	30		291
Net loan charge-offs	13		263
Ending Balance	7,269		7,269
Real Estate - Commercial Mortgage [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			1,458
Real Estate - Residential [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		3,210		3,400
Provision for Credit Losses		3		(125)
Charge-Offs		(44)		(373)
Recoveries		46		313
Net Charge-Offs		2		(60)
Ending Balance		3,215		3,215
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	5,440		3,128
Provision for credit losses	(344)		745
Charge-Offs	(1)		(112)
Recoveries	35		126
Net loan charge-offs	34		14
Ending Balance	5,130		5,130
Real Estate - Residential [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			1,243
Real Estate - Home Equity [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		2,383		2,301
Provision for Credit Losses		71		158
Charge-Offs		(333)		(430)
Recoveries		58		150
Net Charge-Offs		(275)		(280)
Ending Balance		2,179		2,179
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,753		2,224
Provision for credit losses	196		337
Charge-Offs	(58)		(141)
Recoveries	41		138
Net loan charge-offs	(17)		(3)
Ending Balance	2,932		2,932
Real Estate - Home Equity [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			374
Consumer [Member]
Activity in the allowance for loan losses by portfolio class
Beginning Balance		2,942		2,614
Provision for Credit Losses		689		1,797
Charge-Offs		(744)		(2,059)
Recoveries		277		812
Net Charge-Offs		(467)		(1,247)
Ending Balance		$ 3,164		$ 3,164
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	3,201		3,092
Provision for credit losses	831		2,668
Charge-Offs	(1,069)		(3,810)
Recoveries	517		2,126
Net loan charge-offs	(552)		(1,684)
Ending Balance	$ 3,480		3,480
Consumer [Member] | Impact of Adoption of ASC 326 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance			$ (596)