Quarterly report pursuant to Section 13 or 15(d)

LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Including Purchased Impaired Loans) (Details)

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LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Including Purchased Impaired Loans) (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment $ 9,411,598 $ 7,141,552
Construction and Land Development    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,178,054 948,791
Commercial Real Estate - Owner Occupied    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,283,125 943,933
Commercial Real Estate - Non-Owner Occupied    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 2,427,251 1,713,659
Multifamily Real Estate    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 542,662 357,079
Commercial & Industrial    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,154,583 612,023
Residential 1-4 Family - Commercial    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 719,798 612,395
Residential 1-4 Family - Mortgage    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 611,728 485,690
Auto    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 306,196 282,474
HELOC    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 612,116 537,521
Consumer and all other    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 576,085 647,987
Purchased Impaired    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 94,746 39,021
Purchased Impaired | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 29,667 19,017
Purchased Impaired | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 38,804 13,881
Purchased Impaired | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 26,275 5,435
Purchased Impaired | Doubtful    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 0 688
Purchased Impaired | Construction and Land Development    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 5,042 2,838
Purchased Impaired | Construction and Land Development | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,859 1,462
Purchased Impaired | Construction and Land Development | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,232 1,260
Purchased Impaired | Construction and Land Development | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,951 116
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 25,896 14,790
Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 3,546 4,958
Purchased Impaired | Commercial Real Estate - Owner Occupied | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 16,571 7,486
Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 5,779 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 21,575 6,610
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 3,541 3,920
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 13,438 1,394
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 4,596 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 86 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 86 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 2,299 408
Purchased Impaired | Commercial & Industrial | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 839 85
Purchased Impaired | Commercial & Industrial | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 126 123
Purchased Impaired | Commercial & Industrial | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 1,334 200
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 16,073 9,414
Purchased Impaired | Residential 1-4 Family - Commercial | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 5,704 5,234
Purchased Impaired | Residential 1-4 Family - Commercial | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 4,936 2,877
Purchased Impaired | Residential 1-4 Family - Commercial | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 5,433 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 16,761 3,733
Purchased Impaired | Residential 1-4 Family - Mortgage | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 9,735 2,764
Purchased Impaired | Residential 1-4 Family - Mortgage | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 830 329
Purchased Impaired | Residential 1-4 Family - Mortgage | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 6,196 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 9 0
Purchased Impaired | Auto | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 9  
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 6,179 950
Purchased Impaired | HELOC | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 4,354 446
Purchased Impaired | HELOC | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 893 291
Purchased Impaired | HELOC | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 932 94
Purchased Impaired | HELOC | Doubtful    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 0 119
Purchased Impaired | Consumer and all other    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 826 198
Purchased Impaired | Consumer and all other | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 80 148
Purchased Impaired | Consumer and all other | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 692 41
Purchased Impaired | Consumer and all other | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment 54 9
Purchased Impaired | Consumer and all other | Doubtful    
Financing Receivable, Recorded Investment [Line Items]    
Net loans held for investment $ 0 $ 0