LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Stated at Face Amount, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	$ 13,195,843	$ 14,021,314
Total Allowance for credit losses	(99,787)	(160,540)	$ (94,838)	$ (43,194)
Total loans held for investment, net	13,096,056	13,860,774
Loans receivable, deferred fees and costs	49,300	69,700
Construction and Land Development
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	862,236	925,798
Commercial Real Estate - Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	1,995,409	2,128,909
Commercial Real Estate - Non-Owner Occupied
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	3,789,377	3,657,562
Multifamily Real Estate
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	778,626	814,745
Commercial and Industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	2,542,243	3,263,460
Residential 1-4 Family - Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	607,337	671,949
Residential 1-4 Family - Mortgage
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	816,524	822,866
Residential 1-4 Family - Revolving
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	560,796	596,996
Auto
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	461,052	401,324
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	176,992	247,730
Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans held for investment, net of deferred fees and costs	605,251	489,975
Paycheck Protection Program (PPP) | Commercial and Industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	145,300	1,200,000
Paycheck Protection Program (PPP) | Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans held for investment, net	$ 5,100	$ 11,300