LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Deferred Fees and Costs) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 9,290,259	$ 7,141,552
Loans receivable, deferred fees and costs	2,600	1,300
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,250,448	948,791
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,293,791	943,933
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	2,318,589	1,713,659
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	541,730	357,079
Commercial & Industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,093,771	612,023
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	723,945	612,395
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	607,155	485,690
Auto
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	296,706	282,474
HELOC
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	626,916	537,521
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	298,021	408,667
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 239,187	$ 239,320