LOANS AND ALLOWANCE FOR LOAN LOSSES - Aging of the Recorded Investment in Past Due Loans - (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	$ 15,808	$ 12,843
Past due over 90 days and still accruing	2,135
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	2,651,673	2,155,392
Total Past Due	23,234	14,853
Loans Not Past Due	2,628,439	2,140,539
Accrued interest	7,342	5,878
30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	9,640	5,164
60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	2,229	2,597
Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	11,365	7,092
Commercial
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	534,559	445,664
Commercial | Commercial and industrial
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	882	654
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	461,092	380,960
Total Past Due	176	342
Loans Not Past Due	460,916	380,618
Commercial | Commercial and industrial | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due		93
Commercial | Commercial and industrial | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	176	249
Commercial | Agricultural
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	1,631	7
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	73,467	64,704
Total Past Due	1,821	27
Loans Not Past Due	71,646	64,677
Commercial | Agricultural | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	215	20
Commercial | Agricultural | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,606	7
Commercial Real Estate
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	1,162,696	925,884
Commercial Real Estate | Farm
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	1,347	308
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	111,807	97,916
Total Past Due	1,324	119
Loans Not Past Due	110,483	97,797
Commercial Real Estate | Farm | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	81
Commercial Real Estate | Farm | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,243	119
Commercial Real Estate | Hotel
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	64
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	91,213	72,193
Total Past Due	63	13
Loans Not Past Due	91,150	72,180
Commercial Real Estate | Hotel | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due		13
Commercial Real Estate | Hotel | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	63
Commercial Real Estate | Construction and development
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	122	144
Past due over 90 days and still accruing	2,135
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	102,598	77,394
Total Past Due	3,639	211
Loans Not Past Due	98,959	77,183
Commercial Real Estate | Construction and development | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,416
Commercial Real Estate | Construction and development | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due		67
Commercial Real Estate | Construction and development | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	2,223	144
Commercial Real Estate | Other
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	3,219	4,791
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	857,078	678,381
Total Past Due	3,170	3,576
Loans Not Past Due	853,908	674,805
Commercial Real Estate | Other | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,268	873
Commercial Real Estate | Other | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	90	102
Commercial Real Estate | Other | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,812	2,601
Residential
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	892,513	727,073
Residential | 1-4 family
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	7,163	5,211
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	608,366	438,808
Total Past Due	10,148	8,401
Loans Not Past Due	598,218	430,407
Residential | 1-4 family | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	4,884	3,726
Residential | 1-4 family | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	2,002	1,904
Residential | 1-4 family | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	3,262	2,771
Residential | Home equity
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	1,273	1,639
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	284,147	288,265
Total Past Due	1,881	1,989
Loans Not Past Due	282,266	286,276
Residential | Home equity | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	830	410
Residential | Home equity | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	137	446
Residential | Home equity | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	914	1,133
Consumer
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	61,905	56,771
Consumer | Direct
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Non-accrual	107	89
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	61,574	56,312
Total Past Due	1,002	173
Loans Not Past Due	60,572	56,139
Consumer | Direct | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	936	40
Consumer | Direct | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due		65
Consumer | Direct | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	66	68
Consumer | Indirect
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	331	459
Total Past Due	10	2
Loans Not Past Due	321	457
Consumer | Indirect | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	$ 10	$ 2