LOANS AND ALLOWANCE FOR LOAN LOSSES (Loans Receivables Related Risk Rating Excluding Purchased Impaired Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 11,952,310	$ 9,716,207
Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,326,679	1,194,821
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,921,464	1,337,345
Commercial Real Estate - Non-Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,970,453	2,467,410
Multifamily Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	591,431	548,231
Commercial & Industrial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,866,625	1,317,135
Residential 1-4 Family - Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	815,309	713,750
Residential 1-4 Family - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total Loans	865,502	600,578
Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	300,631	301,943
HELOC
Financing Receivable, Recorded Investment [Line Items]
Total Loans	672,087	613,383
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total Loans	397,491	379,694
Other Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	224,638	241,917
Excluding Purchased Impaired
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11,852,378	9,625,986
Excluding Purchased Impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11,440,676	9,344,002
Excluding Purchased Impaired | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	336,737	201,174
Excluding Purchased Impaired | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	74,960	80,810
Excluding Purchased Impaired | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5	0
Excluding Purchased Impaired | Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,314,079	1,186,167
Excluding Purchased Impaired | Construction and Land Development | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,256,927	1,130,577
Excluding Purchased Impaired | Construction and Land Development | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	44,734	43,894
Excluding Purchased Impaired | Construction and Land Development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	12,413	11,696
Excluding Purchased Impaired | Construction and Land Development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5	0
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,894,628	1,311,701
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,798,015	1,231,422
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	76,629	50,939
Excluding Purchased Impaired | Commercial Real Estate - Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	19,984	29,340
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	2,951,603	2,450,075
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,890,489	2,425,500
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	54,050	17,648
Excluding Purchased Impaired | Commercial Real Estate - Non-Owner Occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,064	6,927
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	591,341	548,143
Excluding Purchased Impaired | Multifamily Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	580,548	537,572
Excluding Purchased Impaired | Multifamily Real Estate | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	10,793	10,571
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	1,862,466	1,314,979
Excluding Purchased Impaired | Commercial & Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,753,278	1,273,549
Excluding Purchased Impaired | Commercial & Industrial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	106,629	34,864
Excluding Purchased Impaired | Commercial & Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,559	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	801,616	700,043
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	766,837	677,109
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	26,790	17,086
Excluding Purchased Impaired | Residential 1-4 Family - Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,989	5,848
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 - Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total Loans	848,322	583,812
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	827,008	554,192
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,776	14,855
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,538	14,765
Excluding Purchased Impaired | Residential 1-4 Family - Mortgage | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Excluding Purchased Impaired | Auto
Financing Receivable, Recorded Investment [Line Items]
Total Loans	300,624	301,936
Excluding Purchased Impaired | Auto | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	296,700	296,907
Excluding Purchased Impaired | Auto | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,207	3,590
Excluding Purchased Impaired | Auto | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,717	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	666,949	608,268
Excluding Purchased Impaired | HELOC | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	654,804	598,444
Excluding Purchased Impaired | HELOC | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,830	6,316
Excluding Purchased Impaired | HELOC | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,315	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	396,798	379,662
Excluding Purchased Impaired | Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	395,747	378,873
Excluding Purchased Impaired | Consumer | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	778	547
Excluding Purchased Impaired | Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	273	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	223,952	241,200
Excluding Purchased Impaired | Other Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	220,323	239,857
Excluding Purchased Impaired | Other Commercial | Watch & Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,521	864
Excluding Purchased Impaired | Other Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	108	479
Excluding Purchased Impaired | Other Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 0	$ 0