LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Abstract]
Loans receivable, deferred fees and costs	$ 5,100	$ 1,300
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	9,716,207	7,141,552
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	1,194,821	948,791
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	1,337,345	943,933
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	2,467,410	1,713,659
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	548,231	357,079
Commercial and Industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	1,317,135	612,023
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	713,750	612,395
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	600,578	485,690
Auto
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	301,943	282,474
HELOC
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	613,383	537,521
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	379,694	408,667
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees	$ 241,917	$ 239,320