ALLOWANCE FOR LOAN LOSSES - Loans by Credit Risk Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Credit quality information
Loans	$ 2,634,983	$ 2,641,092
Total commercial real estate
Credit quality information
Loans	948,178	930,661
Total commercial real estate | Construction and land development
Credit quality information
Loans	51,579	34,290
Total commercial real estate | Other commercial real estate
Credit quality information
Loans	896,599	896,371
Commercial and industrial
Credit quality information
Loans	426,357	423,291
Commercial and industrial | Commercial
Credit quality information
Loans	340,795	298,764
Commercial and industrial | Agricultural
Credit quality information
Loans	18,797	20,224
Commercial and industrial | Tax exempt
Credit quality information
Loans	66,765	104,303
Special mention
Credit quality information
Loans	14,619	16,230
Substandard
Credit quality information
Loans	37,888	39,442
Non-accrual
Credit quality information
Loans	10,056	11,550
Total classified
Credit quality information
Loans	47,944	50,992
Total Criticized
Credit quality information
Loans	62,563	67,222
Business Activities Loans
Credit quality information
Loans	1,908,558	1,835,230
Business Activities Loans | Total commercial real estate
Credit quality information
Loans	729,735	697,438
Business Activities Loans | Total commercial real estate | Construction and land development
Credit quality information
Loans	49,157	31,387
Business Activities Loans | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	680,578	666,051
Business Activities Loans | Commercial and industrial
Credit quality information
Loans	362,373	326,570
Business Activities Loans | Commercial and industrial | Commercial
Credit quality information
Loans	288,082	239,692
Business Activities Loans | Commercial and industrial | Agricultural
Credit quality information
Loans	18,597	20,018
Business Activities Loans | Commercial and industrial | Tax exempt
Credit quality information
Loans	55,694	66,860
Business Activities Loans | Residential real estate and consumer
Credit quality information
Loans	816,450	811,222
Business Activities Loans | Residential real estate and consumer | Residential mortgages
Credit quality information
Loans	742,710	740,687
Business Activities Loans | Residential real estate and consumer | Home equity
Credit quality information
Loans	64,514	59,368
Business Activities Loans | Residential real estate and consumer | Other consumer
Credit quality information
Loans	9,226	11,167
Business Activities Loans | Performing | Residential real estate and consumer
Credit quality information
Loans	811,913	807,224
Business Activities Loans | Performing | Residential real estate and consumer | Residential mortgages
Credit quality information
Loans	738,633	737,325
Business Activities Loans | Performing | Residential real estate and consumer | Home equity
Credit quality information
Loans	64,074	58,753
Business Activities Loans | Performing | Residential real estate and consumer | Other consumer
Credit quality information
Loans	9,206	11,146
Business Activities Loans | Nonperforming | Residential real estate and consumer
Credit quality information
Loans	4,537	3,998
Business Activities Loans | Nonperforming | Residential real estate and consumer | Residential mortgages
Credit quality information
Loans	4,077	3,362
Business Activities Loans | Nonperforming | Residential real estate and consumer | Home equity
Credit quality information
Loans	440	615
Business Activities Loans | Nonperforming | Residential real estate and consumer | Other consumer
Credit quality information
Loans	20	21
Business Activities Loans | Pass | Total commercial real estate
Credit quality information
Loans	708,375	677,943
Business Activities Loans | Pass | Total commercial real estate | Construction and land development
Credit quality information
Loans	48,881	31,057
Business Activities Loans | Pass | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	659,494	646,886
Business Activities Loans | Pass | Commercial and industrial
Credit quality information
Loans	341,540	307,129
Business Activities Loans | Pass | Commercial and industrial | Commercial
Credit quality information
Loans	268,287	221,329
Business Activities Loans | Pass | Commercial and industrial | Agricultural
Credit quality information
Loans	17,559	18,940
Business Activities Loans | Pass | Commercial and industrial | Tax exempt
Credit quality information
Loans	55,694	66,860
Business Activities Loans | Special mention
Credit quality information
Loans	11,995	8,525
Business Activities Loans | Special mention | Total commercial real estate
Credit quality information
Loans	8,133	5,483
Business Activities Loans | Special mention | Total commercial real estate | Construction and land development
Credit quality information
Loans	0	0
Business Activities Loans | Special mention | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	8,133	5,483
Business Activities Loans | Special mention | Commercial and industrial
Credit quality information
Loans	3,862	3,042
Business Activities Loans | Special mention | Commercial and industrial | Commercial
Credit quality information
Loans	3,641	2,744
Business Activities Loans | Special mention | Commercial and industrial | Agricultural
Credit quality information
Loans	221	298
Business Activities Loans | Special mention | Commercial and industrial | Tax exempt
Credit quality information
Loans	0	0
Business Activities Loans | Substandard
Credit quality information
Loans	26,351	26,055
Business Activities Loans | Substandard | Total commercial real estate
Credit quality information
Loans	11,835	12,304
Business Activities Loans | Substandard | Total commercial real estate | Construction and land development
Credit quality information
Loans	11	330
Business Activities Loans | Substandard | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	11,824	11,974
Business Activities Loans | Substandard | Commercial and industrial
Credit quality information
Loans	15,651	15,646
Business Activities Loans | Substandard | Commercial and industrial | Commercial
Credit quality information
Loans	15,195	14,866
Business Activities Loans | Substandard | Commercial and industrial | Agricultural
Credit quality information
Loans	456	780
Business Activities Loans | Substandard | Commercial and industrial | Tax exempt
Credit quality information
Loans	0	0
Business Activities Loans | Doubtful | Total commercial real estate
Credit quality information
Loans	1,392	1,708
Business Activities Loans | Doubtful | Total commercial real estate | Construction and land development
Credit quality information
Loans	265	0
Business Activities Loans | Doubtful | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	1,127	1,708
Business Activities Loans | Doubtful | Commercial and industrial
Credit quality information
Loans	1,320	753
Business Activities Loans | Doubtful | Commercial and industrial | Commercial
Credit quality information
Loans	959	753
Business Activities Loans | Doubtful | Commercial and industrial | Agricultural
Credit quality information
Loans	361	0
Business Activities Loans | Doubtful | Commercial and industrial | Tax exempt
Credit quality information
Loans	0	0
Business Activities Loans | Non-accrual
Credit quality information
Loans	8,384	8,354
Business Activities Loans | Total classified
Credit quality information
Loans	34,735	34,409
Business Activities Loans | Total classified | Commercial and industrial
Credit quality information
Loans	362,373	326,570
Business Activities Loans | Total classified | Commercial and industrial | Commercial
Credit quality information
Loans	288,082	239,692
Business Activities Loans | Total classified | Commercial and industrial | Agricultural
Credit quality information
Loans	18,597	20,018
Business Activities Loans | Total classified | Commercial and industrial | Tax exempt
Credit quality information
Loans	55,694	66,860
Business Activities Loans | Total Criticized
Credit quality information
Loans	46,730	42,934
Business Activities Loans | Total Criticized | Total commercial real estate
Credit quality information
Loans	729,735	697,438
Business Activities Loans | Total Criticized | Total commercial real estate | Construction and land development
Credit quality information
Loans	49,157	31,387
Business Activities Loans | Total Criticized | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	680,578	666,051
Acquired Loans
Credit quality information
Loans	726,425	805,862
Acquired Loans | Total commercial real estate
Credit quality information
Loans	218,443	233,223
Acquired Loans | Total commercial real estate | Construction and land development
Credit quality information
Loans	2,422	2,903
Acquired Loans | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	216,021	230,320
Acquired Loans | Commercial and industrial
Credit quality information
Loans	63,984	96,721
Acquired Loans | Commercial and industrial | Commercial
Credit quality information
Loans	52,713	59,072
Acquired Loans | Commercial and industrial | Agricultural
Credit quality information
Loans	200	206
Acquired Loans | Commercial and industrial | Tax exempt
Credit quality information
Loans	11,071	37,443
Acquired Loans | Residential real estate and consumer
Credit quality information
Loans	443,998	475,918
Acquired Loans | Consumer | Home equity
Credit quality information
Loans	53,030	63,033
Acquired Loans | Consumer | Other consumer
Credit quality information
Loans	1,350	1,715
Acquired Loans | Residential real estate | Residential mortgages
Credit quality information
Loans	389,618	411,170
Acquired Loans | Performing | Residential real estate and consumer
Credit quality information
Loans	441,266	472,022
Acquired Loans | Performing | Consumer | Home equity
Credit quality information
Loans	52,619	62,504
Acquired Loans | Performing | Consumer | Other consumer
Credit quality information
Loans	1,343	1,707
Acquired Loans | Performing | Residential real estate | Residential mortgages
Credit quality information
Loans	387,304	407,811
Acquired Loans | Nonperforming | Residential real estate and consumer
Credit quality information
Loans	2,732	3,896
Acquired Loans | Nonperforming | Consumer | Home equity
Credit quality information
Loans	411	529
Acquired Loans | Nonperforming | Consumer | Other consumer
Credit quality information
Loans	7	8
Acquired Loans | Nonperforming | Residential real estate | Residential mortgages
Credit quality information
Loans	2,314	3,359
Acquired Loans | Pass | Total commercial real estate
Credit quality information
Loans	207,392	220,903
Acquired Loans | Pass | Total commercial real estate | Construction and land development
Credit quality information
Loans	2,083	2,412
Acquired Loans | Pass | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	205,309	218,491
Acquired Loans | Pass | Commercial and industrial
Credit quality information
Loans	61,934	88,649
Acquired Loans | Pass | Commercial and industrial | Commercial
Credit quality information
Loans	50,663	51,184
Acquired Loans | Pass | Commercial and industrial | Agricultural
Credit quality information
Loans	200	58
Acquired Loans | Pass | Commercial and industrial | Tax exempt
Credit quality information
Loans	11,071	37,407
Acquired Loans | Special mention
Credit quality information
Loans	2,624	7,705
Acquired Loans | Special mention | Total commercial real estate
Credit quality information
Loans	1,742	2,273
Acquired Loans | Special mention | Total commercial real estate | Construction and land development
Credit quality information
Loans		12
Acquired Loans | Special mention | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	1,742	2,261
Acquired Loans | Special mention | Commercial and industrial
Credit quality information
Loans	882	5,432
Acquired Loans | Special mention | Commercial and industrial | Commercial
Credit quality information
Loans	882	5,432
Acquired Loans | Substandard
Credit quality information
Loans	11,537	13,387
Acquired Loans | Substandard | Total commercial real estate
Credit quality information
Loans	9,239	9,879
Acquired Loans | Substandard | Total commercial real estate | Construction and land development
Credit quality information
Loans	339	479
Acquired Loans | Substandard | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	8,900	9,400
Acquired Loans | Substandard | Commercial and industrial
Credit quality information
Loans	944	2,299
Acquired Loans | Substandard | Commercial and industrial | Commercial
Credit quality information
Loans	944	2,115
Acquired Loans | Substandard | Commercial and industrial | Agricultural
Credit quality information
Loans		148
Acquired Loans | Substandard | Commercial and industrial | Tax exempt
Credit quality information
Loans		36
Acquired Loans | Doubtful | Total commercial real estate
Credit quality information
Loans	70	168
Acquired Loans | Doubtful | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	70	168
Acquired Loans | Doubtful | Commercial and industrial
Credit quality information
Loans	224	341
Acquired Loans | Doubtful | Commercial and industrial | Commercial
Credit quality information
Loans	224	341
Acquired Loans | Non-accrual
Credit quality information
Loans	1,672	3,196
Acquired Loans | Total classified
Credit quality information
Loans	13,209	16,583
Acquired Loans | Total classified | Total commercial real estate
Credit quality information
Loans	218,443	233,223
Acquired Loans | Total classified | Total commercial real estate | Construction and land development
Credit quality information
Loans	2,422	2,903
Acquired Loans | Total classified | Total commercial real estate | Other commercial real estate
Credit quality information
Loans	216,021	230,320
Acquired Loans | Total classified | Commercial and industrial
Credit quality information
Loans	63,984	96,721
Acquired Loans | Total classified | Commercial and industrial | Commercial
Credit quality information
Loans	52,713	59,072
Acquired Loans | Total classified | Commercial and industrial | Agricultural
Credit quality information
Loans	200	206
Acquired Loans | Total classified | Commercial and industrial | Tax exempt
Credit quality information
Loans	11,071	37,443
Acquired Loans | Total Criticized
Credit quality information
Loans	$ 15,833	$ 24,288