LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	$ 12,610,936	$ 9,716,207
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	1,250,924	1,194,821
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	2,041,243	1,337,345
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	3,286,098	2,467,410
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	633,743	548,231
Commercial and Industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	2,114,033	1,317,135
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	724,337	640,419
Residential 1-4 Family - Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	890,503	673,909
Residential 1-4 Family - Revolving
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	659,504	613,383
Auto
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	350,419	301,943
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	372,853	379,694
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	$ 287,279	$ 241,917