LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Excluding Purchased Impaired Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 9,411,598	$ 7,141,552
Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,178,054	948,791
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,283,125	943,933
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,427,251	1,713,659
Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	542,662	357,079
Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,154,583	612,023
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	719,798	612,395
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total Loans	611,728	485,690
Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	306,196	282,474
HELOC
Financing Receivable, Recorded Investment [Line Items]
Total Loans	612,116	537,521
Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	576,085	647,987
Excluding Purchased Impaired
Financing Receivable, Recorded Investment [Line Items]
Total Loans	9,316,852	7,102,531
Excluding Purchased Impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	9,051,611	6,880,526
Excluding Purchased Impaired | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	187,078	184,654
Excluding Purchased Impaired | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	78,028	34,114
Excluding Purchased Impaired | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	135	3,237
Excluding Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,173,012	945,953
Excluding Purchased Impaired | Construction and Land Development | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,112,422	869,111
Excluding Purchased Impaired | Construction and Land Development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	49,278	62,517
Excluding Purchased Impaired | Construction and Land Development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11,299	14,325
Excluding Purchased Impaired | Construction and Land Development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	13	0
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,257,229	929,143
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,191,608	872,130
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	37,261	52,268
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,360	4,745
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,405,676	1,707,049
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,377,408	1,681,314
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,536	19,899
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,732	5,836
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	542,576	356,999
Excluding Purchased Impaired | Multifamily Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	530,613	349,625
Excluding Purchased Impaired | Multifamily Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11,963	7,374
Excluding Purchased Impaired | Multifamily Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	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	1,152,284	611,615
Excluding Purchased Impaired | Commercial & Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,107,669	595,923
Excluding Purchased Impaired | Commercial & Industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	36,496	13,533
Excluding Purchased Impaired | Commercial & Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	8,119	2,159
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	703,725	602,981
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	686,249	587,169
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	12,729	12,117
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,747	3,650
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	45
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total Loans	594,967	481,957
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	575,419	470,646
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,540	7,190
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	13,928	1,642
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	80	2,479
Excluding Purchased Impaired | Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	306,187	282,474
Excluding Purchased Impaired | Auto | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	302,347	278,063
Excluding Purchased Impaired | Auto | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,612	4,131
Excluding Purchased Impaired | Auto | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,208	119
Excluding Purchased Impaired | Auto | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	20	161
Excluding Purchased Impaired | HELOC
Financing Receivable, Recorded Investment [Line Items]
Total Loans	605,937	536,571
Excluding Purchased Impaired | HELOC | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	596,925	531,358
Excluding Purchased Impaired | HELOC | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,177	3,867
Excluding Purchased Impaired | HELOC | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,835	857
Excluding Purchased Impaired | HELOC | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	489
Excluding Purchased Impaired | Consumer and all other
Financing Receivable, Recorded Investment [Line Items]
Total Loans	575,259	647,789
Excluding Purchased Impaired | Consumer and all other | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	570,951	645,187
Excluding Purchased Impaired | Consumer and all other | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,486	1,758
Excluding Purchased Impaired | Consumer and all other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	800	781
Excluding Purchased Impaired | Consumer and all other | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 22	$ 63