LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Deferred Fees and Costs) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 9,411,598	$ 7,141,552
Loans receivable, deferred fees and costs	3,500	1,300
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,178,054	948,791
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,283,125	943,933
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	2,427,251	1,713,659
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	542,662	357,079
Commercial & Industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,154,583	612,023
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	719,798	612,395
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	611,728	485,690
Auto
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	306,196	282,474
HELOC
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	612,116	537,521
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	345,320	408,667
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 230,765	$ 239,320