LOANS AND ALLOWANCE FOR LOAN LOSSES (PCI Loan Portfolios by Segment and Delinquency Status) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 9,537,156	$ 7,053,016
Total Loans	9,716,207	7,141,552
Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	71,213	35,418
Total Loans	90,221	39,021
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,177,204	936,857
Total Loans	1,194,821	948,791
Construction and Land Development | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	7,122	2,773
Total Loans	8,654	2,838
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,294,975	925,910
Total Loans	1,337,345	943,933
Commercial Real Estate - Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	20,705	13,931
Total Loans	25,644	14,790
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,447,907	1,703,592
Total Loans	2,467,410	1,713,659
Commercial Real Estate - Non-Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	15,464	6,189
Total Loans	17,335	6,610
Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	547,997	356,999
Total Loans	548,231	357,079
Multifamily Real Estate | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	88	80
Total Loans	88	80
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,309,581	609,829
Total Loans	1,317,135	612,023
Commercial and Industrial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,017	408
Total Loans	2,156	408
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	687,957	598,935
Total Loans	713,750	612,395
Residential 1-4 Family - Commercial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9,312	8,630
Total Loans	13,707	9,414
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	556,907	468,763
Total Loans	600,578	485,690
Residential 1-4 Family - Mortgage | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	12,455	2,764
Total Loans	16,766	3,733
Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	297,442	278,295
Total Loans	301,943	282,474
Auto | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	7
Total Loans	7	0
HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	600,055	531,180
Total Loans	613,383	537,521
HELOC | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	4,365	445
Total Loans	5,115	950
Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	617,131	642,656
Total Loans	621,611	647,987
Consumer and all other | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	678	198
Total Loans	749	198
30 To 89 Days Past Due | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,264	1,644
30 To 89 Days Past Due | Construction and Land Development | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	108	8
30 To 89 Days Past Due | Commercial Real Estate - Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	658	381
30 To 89 Days Past Due | Commercial Real Estate - Non-Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	61	188
30 To 89 Days Past Due | Multifamily Real Estate | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
30 To 89 Days Past Due | Commercial and Industrial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	47	0
30 To 89 Days Past Due | Residential 1-4 Family - Commercial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	931	433
30 To 89 Days Past Due | Residential 1-4 Family - Mortgage | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,899	343
30 To 89 Days Past Due | Auto | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0
30 To 89 Days Past Due | HELOC | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	498	291
30 To 89 Days Past Due | Consumer and all other | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	62	0
Greater Than 90 Days and still Accruing | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	14,744	1,959
Greater Than 90 Days and still Accruing | Construction and Land Development | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,424	57
Greater Than 90 Days and still Accruing | Commercial Real Estate - Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,281	478
Greater Than 90 Days and still Accruing | Commercial Real Estate - Non-Owner Occupied | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,810	233
Greater Than 90 Days and still Accruing | Multifamily Real Estate | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Greater Than 90 Days and still Accruing | Commercial and Industrial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,092	0
Greater Than 90 Days and still Accruing | Residential 1-4 Family - Commercial | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,464	351
Greater Than 90 Days and still Accruing | Residential 1-4 Family - Mortgage | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,412	626
Greater Than 90 Days and still Accruing | Auto | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0
Greater Than 90 Days and still Accruing | HELOC | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	252	214
Greater Than 90 Days and still Accruing | Consumer and all other | Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 9	$ 0