LOANS AND ALLOWANCE FOR LOAN LOSSES (Summary of Aging of the Loan Portfolio by Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	$ 2,630	$ 3,532
Total Loans	9,805,723	7,141,552	$ 6,554,046
Nonaccrual	25,138	21,743
Current	9,636,112	7,053,016
Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	102,861	39,021	57,770
Current	85,028	35,418
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	29,690	16,873
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	9,292	7,367
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	322	1,340
Total Loans	1,249,196	948,791	770,287
Nonaccrual	6,391	5,610
Current	1,230,587	936,857
Construction and Land Development | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	10,202	2,838	2,776
Current	8,239	2,773
Construction and Land Development | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	403	1,248
Construction and Land Development | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,291	898
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	0	0
Total Loans	1,279,155	943,933	870,559
Nonaccrual	2,539	2,708
Current	1,245,028	925,910
Commercial Real Estate - Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	25,826	14,790	18,199
Current	20,393	13,931
Commercial Real Estate - Owner Occupied | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,985	444
Commercial Real Estate - Owner Occupied | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	777	81
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	0	194
Total Loans	2,230,463	1,713,659	1,631,767
Nonaccrual	2,089	2,992
Current	2,206,913	1,703,592
Commercial Real Estate - Non-Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	19,594	6,610	16,725
Current	17,856	6,189
Commercial Real Estate - Non-Owner Occupied | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,867	187
Commercial Real Estate - Non-Owner Occupied | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	84
Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	0	0
Total Loans	547,520	357,079	353,769
Nonaccrual	0	0
Current	544,140	356,999
Multifamily Real Estate | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	3,380	80	2,058
Current	3,380	80
Multifamily Real Estate | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Multifamily Real Estate | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	200	214
Total Loans	1,125,733	612,023	576,567
Nonaccrual	1,969	316
Current	1,116,812	609,829
Commercial & Industrial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,890	408	733
Current	2,732	408
Commercial & Industrial | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,608	1,147
Commercial & Industrial | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,254	109
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	113	579
Total Loans	714,660	612,395	580,568
Nonaccrual	1,512	1,085
Current	693,542	598,935
Residential 1-4 Family - Commercial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	14,826	9,414	11,946
Current	12,989	8,630
Residential 1-4 Family - Commercial | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,707	1,682
Residential 1-4 Family - Commercial | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	960	700
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	1,148	546
Total Loans	604,354	485,690	476,871
Nonaccrual	7,929	6,269
Current	567,153	468,763
Residential 1-4 Family - Mortgage | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	20,517	3,733	3,964
Current	14,768	2,764
Residential 1-4 Family - Mortgage | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	6,210	3,838
Residential 1-4 Family - Mortgage | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,397	2,541
Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	170	40
Total Loans	288,089	282,474	271,466
Nonaccrual	394	413
Current	285,151	278,295
Auto | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	14	0	0
Current	14
Auto | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,167	3,541
Auto | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	193	185
HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	306	217
Total Loans	642,084	537,521	527,863
Nonaccrual	2,072	2,075
Current	632,912	531,180
HELOC | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,884	950	1,156
Current	1,156	445
HELOC | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,564	2,382
HELOC | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,346	717
Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days and still Accruing	371	402
Total Loans	1,124,469	647,987	494,329
Nonaccrual	243	275
Current	1,113,874	642,656
Consumer and all other | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	3,728	198	$ 213
Current	3,501	198
Consumer and all other | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,179	2,404
Consumer and all other | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 2,074	$ 2,052