LOANS AND ALLOWANCE FOR LOAN LOSSES (Summary of Aging of the Loan Portfolio by Segment) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	$ 3,532	$ 3,005
Total Loans	7,141,552	6,307,060	$ 5,671,462
Nonaccrual	21,743	9,973	11,900
Current	7,053,016	6,209,924
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	16,873	20,245
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	7,367	4,621
Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	39,021	59,292	73,737
Current	35,418	55,244
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	1,340	76
Total Loans	948,791	751,131	749,720
Nonaccrual	5,610	2,037
Current	936,857	744,702
Construction and Land Development | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,248	1,162
Construction and Land Development | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	898	232
Construction and Land Development | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,838	2,922	5,986
Current	2,773	2,838
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	0	35
Total Loans	943,933	857,805	860,086
Nonaccrual	2,708	794
Current	925,910	836,682
Commercial Real Estate - Owner Occupied | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	444	1,842
Commercial Real Estate - Owner Occupied | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	81	109
Commercial Real Estate - Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	14,790	18,343	27,388
Current	13,931	17,553
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	194	0
Total Loans	1,713,659	1,564,295	1,270,480
Nonaccrual	2,992	0
Current	1,703,592	1,544,623
Commercial Real Estate - Non-Owner Occupied | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	187	2,369
Commercial Real Estate - Non-Owner Occupied | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	84	0
Commercial Real Estate - Non-Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	6,610	17,303	13,519
Current	6,189	16,768
Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	0	0
Total Loans	357,079	334,276	322,528
Nonaccrual	0	0
Current	356,999	332,063
Multifamily Real Estate | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	147
Multifamily Real Estate | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Multifamily Real Estate | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	80	2,066	1,555
Current	80	2,066
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	214	9
Total Loans	612,023	551,526	435,365
Nonaccrual	316	124
Current	609,829	548,702
Commercial and Industrial | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,147	759
Commercial and Industrial | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	109	858
Commercial and Industrial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	408	1,074	1,813
Current	408	974
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	579	600
Total Loans	612,395	551,636	517,063
Nonaccrual	1,085	1,071
Current	598,935	535,874
Residential 1-4 Family - Commercial | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,682	1,722
Residential 1-4 Family - Commercial | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	700	147
Residential 1-4 Family - Commercial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	9,414	12,222	16,119
Current	8,630	11,165
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	546	1,448
Total Loans	485,690	477,911	461,406
Nonaccrual	6,269	4,208
Current	468,763	462,574
Residential 1-4 Family - Mortgage | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,838	5,316
Residential 1-4 Family - Mortgage | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,541	387
Residential 1-4 Family - Mortgage | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	3,733	3,978	5,040
Current	2,764	2,792
Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	40	111
Total Loans	282,474	262,071	234,061
Nonaccrual	413	169
Current	278,295	258,904
Auto | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,541	2,570
Auto | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	185	317
Auto | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	0	0	0
HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	217	635
Total Loans	537,521	526,884	516,726
Nonaccrual	2,075	1,279
Current	531,180	520,833
HELOC | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,382	1,836
HELOC | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	717	1,140
HELOC | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	950	1,161	1,791
Current	445	865
Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater Than 90 Days and Still Accruing	402	91
Total Loans	647,987	429,525	304,027
Nonaccrual	275	291
Current	642,656	424,967
Consumer and all other | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,404	2,522
Consumer and all other | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,052	1,431
Consumer and all other | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	198	223	$ 526
Current	$ 198	$ 223