LOANS AND ALLOWANCE FOR LOAN LOSSES - Aging of the Recorded Investment in Past Due Loans - (Details) - USD ($) $ in Thousands	Sep. 30, 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	$ 14,944	$ 12,843
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	2,584,907	2,155,392
Total Past Due	15,137	14,853
Loans Not Past Due	2,569,770	2,140,539
Accrued interest	6,911	5,878
30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	3,057	5,164
60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	2,822	2,597
Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	9,258	7,092
Commercial
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	490,359	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	569	654
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	422,614	380,960
Total Past Due	479	342
Loans Not Past Due	422,135	380,618
Commercial | Commercial and industrial | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	172	93
Commercial | Commercial and industrial | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	98
Commercial | Commercial and industrial | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	209	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	1,548	7
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	67,745	64,704
Total Past Due	1,614	27
Loans Not Past Due	66,131	64,677
Commercial | Agricultural | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	17	20
Commercial | Agricultural | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	49
Commercial | Agricultural | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,548	7
Commercial Real Estate
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	1,125,996	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	1,352	308
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	109,507	97,916
Total Past Due	1,249	119
Loans Not Past Due	108,258	97,797
Commercial Real Estate | Farm | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	316
Commercial Real Estate | Farm | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	933	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	63
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	90,929	72,193
Total Past Due	64	13
Loans Not Past Due	90,865	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	64
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	44	144
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	87,722	77,394
Total Past Due	67	211
Loans Not Past Due	87,655	77,183
Commercial Real Estate | Construction and development | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	23	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	44	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	837,838	678,381
Total Past Due	2,381	3,576
Loans Not Past Due	835,457	674,805
Commercial Real Estate | Other | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	445	873
Commercial Real Estate | Other | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	344	102
Commercial Real Estate | Other | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,592	2,601
Residential
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	907,525	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	6,810	5,211
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	621,259	438,808
Total Past Due	7,600	8,401
Loans Not Past Due	613,659	430,407
Residential | 1-4 family | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,795	3,726
Residential | 1-4 family | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	1,766	1,904
Residential | 1-4 family | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	4,039	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	1,242	1,639
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	286,266	288,265
Total Past Due	1,554	1,989
Loans Not Past Due	284,712	286,276
Residential | Home equity | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	586	410
Residential | Home equity | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	206	446
Residential | Home equity | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	762	1,133
Consumer
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	61,027	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	97	89
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	60,675	56,312
Total Past Due	129	173
Loans Not Past Due	60,546	56,139
Consumer | Direct | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	42	40
Consumer | Direct | 60-89 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	20	65
Consumer | Direct | Greater Than 90 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due	67	68
Consumer | Indirect
Aging of the recorded investment in past due loans
Total ending loan balance excluding accrued interest	352	459
Total Past Due		2
Loans Not Past Due	$ 352	457
Consumer | Indirect | 30-59 Days Past Due
Aging of the recorded investment in past due loans
Total Past Due		$ 2