LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Including Purchased Impaired Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	$ 6,898,729	$ 6,307,060	$ 6,148,918
Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	841,738	751,131	776,430
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	903,523	857,805	857,142
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,748,039	1,564,295	1,454,828
Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	368,686	334,276	339,313
Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	554,522	551,526	509,857
Residential 1-4 Family
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,083,112	1,029,547	999,361
HELOC
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	535,446	526,884	524,097
Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	587,091	429,525	432,702
Purchased Impaired
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	51,041	59,292	62,346
Purchased Impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	26,125	27,569
Purchased Impaired | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	16,774	21,837
Purchased Impaired | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	7,245	9,256
Purchased Impaired | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	897	630
Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	3,026	2,922	3,205
Purchased Impaired | Construction and Land Development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,460	1,092
Purchased Impaired | Construction and Land Development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,311	1,432
Purchased Impaired | Construction and Land Development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	255	398
Purchased Impaired | Construction and Land Development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	17,668	18,343	19,064
Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	5,521	5,520
Purchased Impaired | Commercial Real Estate - Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	8,237	8,889
Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	3,910	3,934
Purchased Impaired | Commercial Real Estate - Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	14,376	17,303	18,141
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	10,676	10,927
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	2,435	4,638
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,265	1,738
Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	77	2,066	2,079
Purchased Impaired | Multifamily Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	343
Purchased Impaired | Multifamily Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	77	1,723
Purchased Impaired | Multifamily Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Multifamily Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	625	1,074	1,145
Purchased Impaired | Commercial & Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	94	107
Purchased Impaired | Commercial & Industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	309	480
Purchased Impaired | Commercial & Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	222	487
Purchased Impaired | Commercial & Industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	0	0
Purchased Impaired | Residential 1-4 Family
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	14,077	16,200	16,828
Purchased Impaired | Residential 1-4 Family | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	7,498	8,557
Purchased Impaired | Residential 1-4 Family | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	4,227	4,455
Purchased Impaired | Residential 1-4 Family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	1,577	2,672
Purchased Impaired | Residential 1-4 Family | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	775	516
Purchased Impaired | HELOC
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	982	1,161	1,498
Purchased Impaired | HELOC | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	722	857
Purchased Impaired | HELOC | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	132	183
Purchased Impaired | HELOC | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	6	7
Purchased Impaired | HELOC | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	122	114
Purchased Impaired | Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	210	223	$ 386
Purchased Impaired | Consumer and all other | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	154	166
Purchased Impaired | Consumer and all other | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	46	37
Purchased Impaired | Consumer and all other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	10	20
Purchased Impaired | Consumer and all other | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment, net of deferred fees and costs	$ 0	$ 0