ALLOWANCE FOR CREDIT LOSSES - Loans by risk grades and loan class (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Amortized cost of loans by loan type
Total gross loans	$ 2,876,427,000	$ 2,936,670,000
Pass
Amortized cost of loans by loan type
Total gross loans	2,783,385,000	2,835,768,000
Special Mention
Amortized cost of loans by loan type
Total gross loans	12,807,000	14,088,000
Substandard
Amortized cost of loans by loan type
Total gross loans	80,235,000	86,814,000
Loss or Doubtful
Amortized cost of loans by loan type
Total gross loans	0	0
Commercial and industrial
Amortized cost of loans by loan type
Total gross loans	634,384,000	742,957,000
Commercial and industrial | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	634,384,000	742,957,000
Commercial and industrial | Pass
Amortized cost of loans by loan type
Total gross loans	613,419,000	720,465,000
Commercial and industrial | Special Mention
Amortized cost of loans by loan type
Total gross loans	3,482,000	3,404,000
Commercial and industrial | Substandard
Amortized cost of loans by loan type
Total gross loans	17,483,000	19,088,000
Commercial real estate
Amortized cost of loans by loan type
Total gross loans	1,091,969,000	1,041,998,000
Commercial real estate | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	1,091,969,000	1,041,998,000
Commercial real estate | Pass
Amortized cost of loans by loan type
Total gross loans	1,038,401,000	1,000,503,000
Commercial real estate | Special Mention
Amortized cost of loans by loan type
Total gross loans	8,855,000	7,519,000
Commercial real estate | Substandard
Amortized cost of loans by loan type
Total gross loans	44,713,000	33,976,000
Construction and development
Amortized cost of loans by loan type
Total gross loans	460,719,000	522,705,000
Construction and development | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	460,719,000	522,705,000
Construction and development | Pass
Amortized cost of loans by loan type
Total gross loans	447,533,000	502,933,000
Construction and development | Special Mention
Amortized cost of loans by loan type
Total gross loans	470,000
Construction and development | Substandard
Amortized cost of loans by loan type
Total gross loans	12,716,000	19,772,000
1-4 family residential
Amortized cost of loans by loan type
Total gross loans	277,273,000	239,872,000
1-4 family residential | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	277,273,000	239,872,000
1-4 family residential | Pass
Amortized cost of loans by loan type
Total gross loans	272,217,000	230,654,000
1-4 family residential | Special Mention
Amortized cost of loans by loan type
Total gross loans		3,165,000
1-4 family residential | Substandard
Amortized cost of loans by loan type
Total gross loans	5,056,000	6,053,000
Multifamily residential
Amortized cost of loans by loan type
Total gross loans	286,396,000	258,346,000
Multifamily residential | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	286,396,000	258,346,000
Multifamily residential | Pass
Amortized cost of loans by loan type
Total gross loans	286,396,000	258,346,000
Consumer
Amortized cost of loans by loan type
Total gross loans	28,090,000	33,884,000
Consumer | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	28,090,000	33,884,000
Consumer | Pass
Amortized cost of loans by loan type
Total gross loans	27,865,000	33,884,000
Consumer | Substandard
Amortized cost of loans by loan type
Total gross loans	225,000
Agriculture
Amortized cost of loans by loan type
Total gross loans	7,941,000	8,670,000
Agriculture | Loans by risk grades
Amortized cost of loans by loan type
Total gross loans	7,941,000	8,670,000
Agriculture | Pass
Amortized cost of loans by loan type
Total gross loans	7,899,000	8,597,000
Agriculture | Substandard
Amortized cost of loans by loan type
Total gross loans	42,000	73,000
Other
Amortized cost of loans by loan type
Total gross loans	89,655,000	88,238,000
Other | Pass
Amortized cost of loans by loan type
Total gross loans	$ 89,655,000	80,386,000
Other | Substandard
Amortized cost of loans by loan type
Total gross loans		$ 7,852,000