LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Loans receivable, deferred fees and costs	$ 1,300	$ 1,800
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	7,141,552	6,307,060	$ 5,671,462
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	948,791	751,131	749,720
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	943,933	857,805	860,086
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	1,713,659	1,564,295	1,270,480
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	357,079	334,276	322,528
Commercial and Industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	612,023	551,526	435,365
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	612,395	551,636	517,063
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	485,690	477,911	461,406
Auto
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	282,474	262,071	234,061
HELOC
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	537,521	526,884	516,726
Consumer and all other
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	$ 647,987	$ 429,525	$ 304,027