LOANS HELD FOR INVESTMENT AND ALLOWANCE FOR CREDIT LOSSES (Loan Portfolio Aging) (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Aging of the recorded investment in past due loans by class of loans
Total Past Due		$ 5,077	$ 4,871
Total Current		1,852,436	1,826,586
Total Loans		1,862,387	1,835,929
30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		3,836	3,721
60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		1,241	1,150
90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Commercial, Financial and Agricultural [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		949	680
Total Current		247,713	254,239
Total Loans		249,020	255,365
Commercial, Financial and Agricultural [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		495	489
Commercial, Financial and Agricultural [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		454	191
Commercial, Financial and Agricultural [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Real Estate - Construction [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		530	310
Total Current		122,065	114,708
Total Loans		122,595	115,018
Real Estate - Construction [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		530	300
Real Estate - Construction [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	10
Real Estate - Construction [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Real Estate - Commercial Mortgage [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		864	232
Total Current		653,888	623,890
Total Loans		656,084	625,556
Real Estate - Commercial Mortgage [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		233	148
Real Estate - Commercial Mortgage [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		631	84
Real Estate - Commercial Mortgage [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Real Estate - Residential [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		562	825
Total Current		357,954	359,233
Total Loans	[1]	360,730	361,450
Real Estate - Residential [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		562	629
Real Estate - Residential [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	196
Real Estate - Residential [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Real Estate - Home Equity [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		459	175
Total Current		195,292	196,388
Total Loans		196,443	197,360
Real Estate - Home Equity [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		459	155
Real Estate - Home Equity [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	20
Real Estate - Home Equity [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		0	0
Consumer [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		1,713	2,649
Total Current		275,524	278,128
Total Loans		277,515	281,180
Consumer [Member] | 30-59 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		1,557	2,000
Consumer [Member] | 60-89 DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		156	649
Consumer [Member] | 90 +DPD [Member]
Aging of the recorded investment in past due loans by class of loans
Total Past Due		$ 0	$ 0

[1] Includes loans in process with outstanding balances of $ 7.3 million and $ 8.3 million at March 31, 2020 and December 31, 2019 , respective ly. ^{( 2 )} Includes overdraft balances of $ 1.5 million and $1.6 million at March 31, 2020 and December 31, 2019 , respectively.