LOANS AND ALLOWANCE FOR LOAN LOSSES - Aging of Past Due Loans by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 21,587	$ 19,203
Current	3,636,192	3,549,001	[1]
Total ending loans balance	3,657,779	3,568,204
Total loans	3,657,779	3,568,204
30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	10,440	13,396
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	7,437	2,548
Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	3,710	3,259
Construction real estate loans
Financing Receivable, Past Due [Line Items]
Total Past Due	553	1,802
Current	581,388	643,146	[1]
Total loans	581,941	644,948
Construction real estate loans | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	95	1,236
Construction real estate loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	14	229
Construction real estate loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	444	337
1-4 family residential real estate loans
Financing Receivable, Past Due [Line Items]
Total Past Due	13,171	11,472
Current	706,781	776,090	[1]
Total loans	719,952	787,562
1-4 family residential real estate loans | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	7,872	8,788
1-4 family residential real estate loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	2,469	1,077
1-4 family residential real estate loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	2,830	1,607
Commercial real estate loans
Financing Receivable, Past Due [Line Items]
Total Past Due	868	1,590
Current	1,294,878	1,248,618	[1]
Total loans	1,295,746	1,250,208
Commercial real estate loans | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	467	795
Commercial real estate loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	315	259
Commercial real estate loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	86	536
Commercial loans
Financing Receivable, Past Due [Line Items]
Total Past Due	6,262	3,290
Current	550,860	398,231	[1]
Total loans	557,122	401,521
Commercial loans | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	1,423	1,917
Commercial loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	4,516	722
Commercial loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	323	651
Municipal loans
Financing Receivable, Past Due [Line Items]
Total Past Due	64	0
Current	408,964	383,960	[1]
Total loans	409,028	383,960
Municipal loans | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	64	0
Municipal loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Municipal loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Loans to individuals
Financing Receivable, Past Due [Line Items]
Total Past Due	669	1,049
Current	93,321	98,956	[1]
Total loans	93,990	100,005
Loans to individuals | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	519	660
Loans to individuals | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	123	261
Loans to individuals | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 27	$ 128

[1] Prior to the adoption of CECL, PCI loans were measured at fair value at acquisition if the timing and amount of cash flows expected to be collected from those sales could be reasonably estimated.