LOANS AND ALLOWANCE FOR LOAN LOSSES (PCI Loan Portfolios by Segment and Delinquency Status) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 9,242,170	$ 7,053,016
Total Loans	9,411,598	7,141,552
Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,160,172	936,857
Total Loans	1,178,054	948,791
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,245,684	925,910
Total Loans	1,283,125	943,933
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,403,372	1,703,592
Total Loans	2,427,251	1,713,659
Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	542,023	356,999
Total Loans	542,662	357,079
Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,147,957	609,829
Total Loans	1,154,583	612,023
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	696,964	598,935
Total Loans	719,798	612,395
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	575,590	468,763
Total Loans	611,728	485,690
Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	302,738	278,295
Total Loans	306,196	282,474
HELOC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	597,198	531,180
Total Loans	612,116	537,521
Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	570,472	642,656
Total Loans	576,085	647,987
Purchased Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	75,851	35,418
Total Loans	94,746	39,021
Purchased Impaired | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,843	1,644
Purchased Impaired | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	13,052	1,959
Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,640	2,773
Total Loans	5,042	2,838
Purchased Impaired | Construction and Land Development | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	78	8
Purchased Impaired | Construction and Land Development | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,324	57
Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	21,974	13,931
Total Loans	25,896	14,790
Purchased Impaired | Commercial Real Estate - Owner Occupied | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	435	381
Purchased Impaired | Commercial Real Estate - Owner Occupied | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,487	478
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	19,731	6,189
Total Loans	21,575	6,610
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	33	188
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,811	233
Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	86	80
Total Loans	86	80
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	1,165	408
Total Loans	2,299	408
Purchased Impaired | Commercial & Industrial | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Purchased Impaired | Commercial & Industrial | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,134	0
Purchased Impaired | Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	10,385	8,630
Total Loans	16,073	9,414
Purchased Impaired | Residential 1-4 Family - Commercial | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,677	433
Purchased Impaired | Residential 1-4 Family - Commercial | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,011	351
Purchased Impaired | Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	12,693	2,764
Total Loans	16,761	3,733
Purchased Impaired | Residential 1-4 Family - Mortgage | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,242	343
Purchased Impaired | Residential 1-4 Family - Mortgage | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,826	626
Purchased Impaired | Auto
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9
Total Loans	9	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	5,395	445
Total Loans	6,179	950
Purchased Impaired | HELOC | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	337	291
Purchased Impaired | HELOC | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	447	214
Purchased Impaired | Consumer and all other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	773	198
Total Loans	826	198
Purchased Impaired | Consumer and all other | 30 To 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	41	0
Purchased Impaired | Consumer and all other | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 12	$ 0