LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Excluding Purchased Impaired Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 12,306,997	$ 9,716,207
Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,201,149	1,194,821
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,979,052	1,337,345
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,198,580	2,467,410
Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	659,946	548,231
Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,058,133	1,317,135
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	721,185	640,419
Residential 1-4 Family - Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	913,245	673,909
Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	328,456	301,943
HELOC
Financing Receivable, Recorded Investment [Line Items]
Total Loans	660,963	613,383
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	386,848	379,694
Other Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	199,440	241,917
Excluding Purchased Impaired
Financing Receivable, Recorded Investment [Line Items]
Total Loans	12,217,262	9,625,986
Excluding Purchased Impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11,818,482	9,344,002
Excluding Purchased Impaired | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	318,370	201,174
Excluding Purchased Impaired | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	80,169	80,810
Excluding Purchased Impaired | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	241	0
Excluding Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,192,762	1,186,167
Excluding Purchased Impaired | Construction and Land Development | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,148,732	1,130,577
Excluding Purchased Impaired | Construction and Land Development | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	33,136	43,894
Excluding Purchased Impaired | Construction and Land Development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	10,894	11,696
Excluding Purchased Impaired | Construction and Land Development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,951,235	1,311,701
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,850,909	1,231,422
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	78,451	50,939
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,730	29,340
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	145	0
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,181,295	2,450,075
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,124,018	2,425,500
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	54,884	17,648
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,297	6,927
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	96	0
Excluding Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	659,853	548,143
Excluding Purchased Impaired | Multifamily Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	645,193	537,572
Excluding Purchased Impaired | Multifamily Real Estate | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	13,448	10,571
Excluding Purchased Impaired | Multifamily Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,212	0
Excluding Purchased Impaired | Multifamily Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,054,871	1,314,979
Excluding Purchased Impaired | Commercial & Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,949,546	1,273,549
Excluding Purchased Impaired | Commercial & Industrial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	99,337	34,864
Excluding Purchased Impaired | Commercial & Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,988	6,566
Excluding Purchased Impaired | Commercial & Industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	708,948	626,818
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	679,023	606,955
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,772	14,876
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,153	4,987
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Residential 1-4 Family - Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	898,268	657,037
Excluding Purchased Impaired | Residential 1-4 Family - Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	871,391	624,346
Excluding Purchased Impaired | Residential 1-4 Family - Consumer | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,584	17,065
Excluding Purchased Impaired | Residential 1-4 Family - Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,293	15,626
Excluding Purchased Impaired | Residential 1-4 Family - Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	328,449	301,936
Excluding Purchased Impaired | Auto | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	324,396	296,907
Excluding Purchased Impaired | Auto | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,990	3,590
Excluding Purchased Impaired | Auto | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,063	1,439
Excluding Purchased Impaired | Auto | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | HELOC
Financing Receivable, Recorded Investment [Line Items]
Total Loans	656,688	608,268
Excluding Purchased Impaired | HELOC | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	644,019	598,444
Excluding Purchased Impaired | HELOC | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,529	6,316
Excluding Purchased Impaired | HELOC | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,140	3,508
Excluding Purchased Impaired | HELOC | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	386,166	379,662
Excluding Purchased Impaired | Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	384,744	378,873
Excluding Purchased Impaired | Consumer | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,182	547
Excluding Purchased Impaired | Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	240	242
Excluding Purchased Impaired | Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Other Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	198,727	241,200
Excluding Purchased Impaired | Other Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	196,511	239,857
Excluding Purchased Impaired | Other Commercial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,057	864
Excluding Purchased Impaired | Other Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	159	479
Excluding Purchased Impaired | Other Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 0	$ 0