ALLOWANCE FOR CREDIT LOSSES - Risk Grades and loan class (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized cost of loans by loan type
Total loans	$ 2,678,411	$ 2,646,673
Loans by risk grades
Amortized cost of loans by loan type
Total loans		2,646,673
Pass
Amortized cost of loans by loan type
Total loans		2,582,970
Special Mention
Amortized cost of loans by loan type
Total loans		34,742
Substandard
Amortized cost of loans by loan type
Total loans		28,961
Commercial and industrial
Amortized cost of loans by loan type
Total loans	542,650	527,607
Commercial and industrial | Loans by risk grades
Amortized cost of loans by loan type
Total loans	542,650	527,607
Commercial and industrial | Pass
Amortized cost of loans by loan type
Total loans	528,875	513,417
Commercial and industrial | Special Mention
Amortized cost of loans by loan type
Total loans	750	2,963
Commercial and industrial | Substandard
Amortized cost of loans by loan type
Total loans	13,025	11,227
Commercial real estate
Amortized cost of loans by loan type
Total loans	904,395	900,746
Commercial real estate | Loans by risk grades
Amortized cost of loans by loan type
Total loans	904,395	900,746
Commercial real estate | Pass
Amortized cost of loans by loan type
Total loans	879,899	876,207
Commercial real estate | Special Mention
Amortized cost of loans by loan type
Total loans	12,587	18,570
Commercial real estate | Substandard
Amortized cost of loans by loan type
Total loans	11,909	5,969
Construction and development
Amortized cost of loans by loan type
Total loans	558,343	527,812
Construction and development | Loans by risk grades
Amortized cost of loans by loan type
Total loans	558,343	527,812
Construction and development | Pass
Amortized cost of loans by loan type
Total loans	545,792	515,247
Construction and development | Special Mention
Amortized cost of loans by loan type
Total loans		12,565
Construction and development | Substandard
Amortized cost of loans by loan type
Total loans	12,551
1-4 family residential
Amortized cost of loans by loan type
Total loans	276,142	280,192
1-4 family residential | Loans by risk grades
Amortized cost of loans by loan type
Total loans	276,142	280,192
1-4 family residential | Pass
Amortized cost of loans by loan type
Total loans	269,989	274,731
1-4 family residential | Special Mention
Amortized cost of loans by loan type
Total loans	818	594
1-4 family residential | Substandard
Amortized cost of loans by loan type
Total loans	5,335	4,867
Multi‑family residential
Amortized cost of loans by loan type
Total loans	267,152	277,209
Multi‑family residential | Loans by risk grades
Amortized cost of loans by loan type
Total loans	267,152	277,209
Multi‑family residential | Pass
Amortized cost of loans by loan type
Total loans	267,152	277,209
Consumer
Amortized cost of loans by loan type
Total loans	38,133	36,782
Consumer | Loans by risk grades
Amortized cost of loans by loan type
Total loans	38,133	36,782
Consumer | Pass
Amortized cost of loans by loan type
Total loans	38,128	36,566
Consumer | Substandard
Amortized cost of loans by loan type
Total loans	5	216
Agriculture
Amortized cost of loans by loan type
Total loans	7,520	9,812
Agriculture | Loans by risk grades
Amortized cost of loans by loan type
Total loans	7,520	9,812
Agriculture | Pass
Amortized cost of loans by loan type
Total loans	7,443	9,733
Agriculture | Special Mention
Amortized cost of loans by loan type
Total loans		50
Agriculture | Substandard
Amortized cost of loans by loan type
Total loans	77	29
Other
Amortized cost of loans by loan type
Total loans	84,076	86,513
Other | Loans by risk grades
Amortized cost of loans by loan type
Total loans	84,076	86,513
Other | Pass
Amortized cost of loans by loan type
Total loans	75,809	79,860
Other | Substandard
Amortized cost of loans by loan type
Total loans	$ 8,267	$ 6,653