LOANS - Contractual Aging of Recorded Investment in Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	$ 14,375	$ 18,071
Current	3,364,985	2,857,695
Total Financing Receivables	3,384,991	2,879,536
Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,395	2,281
Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	236	1,489
Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Portfolio Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	10,877	11,023
Current	2,822,463	2,412,629
Total Financing Receivables	2,837,490	2,425,850
Portfolio Loans [Member] | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	193	49
Current	474,619	308,652
Total Financing Receivables	476,511	308,731
Portfolio Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	109	170
Current	179,946	152,669
Total Financing Receivables	180,467	152,927
Portfolio Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,870	1,784
Current	1,143,843	1,039,882
Total Financing Receivables	1,146,359	1,041,915
Portfolio Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,027	1,707
Portfolio Loans [Member] | Accruing 30-59 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,699	30
Portfolio Loans [Member] | Accruing 30-59 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	396	29
Portfolio Loans [Member] | Accruing 30-59 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	646	78
Portfolio Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	123	491
Portfolio Loans [Member] | Accruing 60-89 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Portfolio Loans [Member] | Accruing 60-89 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	16	59
Portfolio Loans [Member] | Accruing 60-89 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	171
Portfolio Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Portfolio Loans [Member] | Accruing Greater Than 90 Days | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Portfolio Loans [Member] | Accruing Greater Than 90 Days | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Portfolio Loans [Member] | Accruing Greater Than 90 Days | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Unimpaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	2,299	2,763
Current	533,278	436,540
Total Financing Receivables	537,058	440,690
Purchased Unimpaired Loans [Member] | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	332	197
Current	57,469	60,353
Total Financing Receivables	58,122	60,917
Purchased Unimpaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	4,018	981
Total Financing Receivables	4,018	1,018
Purchased Unimpaired Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	732	1,272
Current	321,166	302,318
Total Financing Receivables	322,758	304,420
Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,368	574
Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	321	39
Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	37
Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	860	345
Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	113	813
Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	328
Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	485
Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,199	4,285
Current	9,244	8,526
Total Financing Receivables	10,443	12,996
Purchased Credit Impaired Loans [Member] | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	824	941
Total Financing Receivables	824	941
Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	0	0
Total Financing Receivables	0	0
Purchased Credit Impaired Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,199	4,285
Current	7,776	6,972
Total Financing Receivables	8,975	11,257
Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	185
Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days | Commercial and financial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days | Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Portfolio Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	364	438
Current	200,223	137,042
Total Financing Receivables	200,860	137,480
Construction and land development [Member] | Portfolio Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	273	0
Construction and land development [Member] | Portfolio Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Portfolio Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Purchased Unimpaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	72	32
Current	44,068	22,490
Total Financing Receivables	44,175	22,522
Construction and land development [Member] | Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	35	0
Construction and land development [Member] | Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	116	114
Total Financing Receivables	116	114
Construction and land development [Member] | Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction and land development [Member] | Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Financing Receivables	941,169	836,787
Residential real estate [Member] | Portfolio Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	8,341	8,582
Current	823,195	773,877
Total Financing Receivables	832,656	784,290
Residential real estate [Member] | Portfolio Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,013	1,570
Residential real estate [Member] | Portfolio Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	107	261
Residential real estate [Member] | Portfolio Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Residential real estate [Member] | Purchased Unimpaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,163	1,262
Current	106,557	50,398
Total Financing Receivables	107,985	51,813
Residential real estate [Member] | Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	152	153
Residential real estate [Member] | Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	113	0
Residential real estate [Member] | Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Residential real estate [Member] | Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	528	499
Total Financing Receivables	528	684
Residential real estate [Member] | Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Residential real estate [Member] | Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	185
Residential real estate [Member] | Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Portfolio Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	637	507
Total Financing Receivables	637	507
Other [Member] | Portfolio Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Portfolio Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Portfolio Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Unimpaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	0	0
Total Financing Receivables	0	0
Other [Member] | Purchased Unimpaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Unimpaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Unimpaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	0
Current	0	0
Total Financing Receivables	0	0
Other [Member] | Purchased Credit Impaired Loans [Member] | Accruing 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Credit Impaired Loans [Member] | Accruing 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Other [Member] | Purchased Credit Impaired Loans [Member] | Accruing Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 0	$ 0