LOANS AND ALLOWANCE FOR LOAN LOSSES (PCI Loan Portfolios by Segment and Delinquency Status) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 9,636,112	$ 7,053,016
Total Loans	9,805,723	7,141,552	$ 6,554,046
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,230,587	936,857
Total Loans	1,249,196	948,791	770,287
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,245,028	925,910
Total Loans	1,279,155	943,933	870,559
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,206,913	1,703,592
Total Loans	2,230,463	1,713,659	1,631,767
Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	544,140	356,999
Total Loans	547,520	357,079	353,769
Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,116,812	609,829
Total Loans	1,125,733	612,023	576,567
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	693,542	598,935
Total Loans	714,660	612,395	580,568
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	567,153	468,763
Total Loans	604,354	485,690	476,871
Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	285,151	278,295
Total Loans	288,089	282,474	271,466
HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	632,912	531,180
Total Loans	642,084	537,521	527,863
Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,113,874	642,656
Total Loans	1,124,469	647,987	494,329
Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	85,028	35,418
Total Loans	102,861	39,021	57,770
Purchased Impaired | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,856	1,644
Purchased Impaired | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	14,977	1,959
Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	8,239	2,773
Total Loans	10,202	2,838	2,776
Purchased Impaired | Construction and Land Development | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	54	8
Purchased Impaired | Construction and Land Development | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,909	57
Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	20,393	13,931
Total Loans	25,826	14,790	18,199
Purchased Impaired | Commercial Real Estate - Owner Occupied | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	438	381
Purchased Impaired | Commercial Real Estate - Owner Occupied | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,995	478
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	17,856	6,189
Total Loans	19,594	6,610	16,725
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	180	188
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,558	233
Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,380	80
Total Loans	3,380	80	2,058
Purchased Impaired | Multifamily Real Estate | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Purchased Impaired | Multifamily Real Estate | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Purchased Impaired | Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,732	408
Total Loans	2,890	408	733
Purchased Impaired | Commercial & Industrial | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	38	0
Purchased Impaired | Commercial & Industrial | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	120	0
Purchased Impaired | Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	12,989	8,630
Total Loans	14,826	9,414	11,946
Purchased Impaired | Residential 1-4 Family - Commercial | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	383	433
Purchased Impaired | Residential 1-4 Family - Commercial | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,454	351
Purchased Impaired | Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	14,768	2,764
Total Loans	20,517	3,733	3,964
Purchased Impaired | Residential 1-4 Family - Mortgage | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,673	343
Purchased Impaired | Residential 1-4 Family - Mortgage | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,076	626
Purchased Impaired | Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	14
Total Loans	14	0	0
Purchased Impaired | Auto | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0
Purchased Impaired | Auto | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0
Purchased Impaired | HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,156	445
Total Loans	1,884	950	1,156
Purchased Impaired | HELOC | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	83	291
Purchased Impaired | HELOC | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	645	214
Purchased Impaired | Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,501	198
Total Loans	3,728	198	$ 213
Purchased Impaired | Consumer and all other | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	7	0
Purchased Impaired | Consumer and all other | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 220	$ 0