LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Deferred Fees and Costs) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 12,220,514	$ 9,716,207
Loans receivable, deferred fees and costs	7,200	5,100
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,267,712	1,194,821
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	1,966,776	1,337,345
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	3,104,823	2,467,410
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	602,115	548,231
Commercial & Industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	2,032,799	1,317,135
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	801,703	713,750
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	850,063	600,578
Auto
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	311,858	301,943
HELOC
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	660,621	613,383
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	383,653	379,694
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 238,391	$ 241,917