LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Including Purchased Impaired Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	$ 9,290,259	$ 7,141,552
Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,250,448	948,791
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,293,791	943,933
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	2,318,589	1,713,659
Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	541,730	357,079
Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,093,771	612,023
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	723,945	612,395
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	607,155	485,690
Auto
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	296,706	282,474
HELOC
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	626,916	537,521
Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	537,208	647,987
Purchased Impaired
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	101,524	39,021
Purchased Impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	32,645	19,017
Purchased Impaired | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	43,711	13,881
Purchased Impaired | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	25,138	5,435
Purchased Impaired | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	30	688
Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	5,183	2,838
Purchased Impaired | Construction and Land Development | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,784	1,462
Purchased Impaired | Construction and Land Development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,286	1,260
Purchased Impaired | Construction and Land Development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	2,113	116
Purchased Impaired | Construction and Land Development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	26,720	14,790
Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	3,643	4,958
Purchased Impaired | Commercial Real Estate - Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	16,444	7,486
Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	6,633	2,346
Purchased Impaired | Commercial Real Estate - Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	24,680	6,610
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	3,507	3,920
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	16,103	1,394
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	5,070	1,296
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	84	80
Purchased Impaired | Multifamily Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Multifamily Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	84	80
Purchased Impaired | Multifamily Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Multifamily Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,851	408
Purchased Impaired | Commercial & Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	871	85
Purchased Impaired | Commercial & Industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	210	123
Purchased Impaired | Commercial & Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	770	200
Purchased Impaired | Commercial & Industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	17,227	9,414
Purchased Impaired | Residential 1-4 Family - Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	6,467	5,234
Purchased Impaired | Residential 1-4 Family - Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	7,235	2,877
Purchased Impaired | Residential 1-4 Family - Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	3,525	1,303
Purchased Impaired | Residential 1-4 Family - Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	0
Purchased Impaired | Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	18,002	3,733
Purchased Impaired | Residential 1-4 Family - Mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	11,661	2,764
Purchased Impaired | Residential 1-4 Family - Mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	768	329
Purchased Impaired | Residential 1-4 Family - Mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	5,573	71
Purchased Impaired | Residential 1-4 Family - Mortgage | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0	569
Purchased Impaired | Auto
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	11	0
Purchased Impaired | Auto | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	11
Purchased Impaired | Auto | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0
Purchased Impaired | Auto | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0
Purchased Impaired | Auto | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	0
Purchased Impaired | HELOC
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	6,890	950
Purchased Impaired | HELOC | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	4,611	446
Purchased Impaired | HELOC | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	854	291
Purchased Impaired | HELOC | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	1,395	94
Purchased Impaired | HELOC | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	30	119
Purchased Impaired | Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	876	198
Purchased Impaired | Consumer and all other | Pass
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	90	148
Purchased Impaired | Consumer and all other | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	727	41
Purchased Impaired | Consumer and all other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	59	9
Purchased Impaired | Consumer and all other | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net loans held for investment	$ 0	$ 0