LOANS - Age Analysis of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	$ 47,576	$ 40,095
90 Days or More Past Due	5,412	375
Total loans past due and still accruing	52,988	40,470
Nonaccrual	64,863	57,338
Purchased Credit Impaired	11,702	15,965
Current	3,006,783	3,076,712
Total loans held for investment	3,136,336	3,190,485	$ 3,012,275
Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	42,606	36,969
90 Days or More Past Due	3,680	375
Total loans past due and still accruing	46,286	37,344
Nonaccrual	60,179	51,860
Purchased Credit Impaired	0	0
Current	2,578,262	2,587,287
Total loans held for investment	2,684,727	2,676,491	2,282,211
Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	4,970	3,126
90 Days or More Past Due	1,732	0
Total loans past due and still accruing	6,702	3,126
Nonaccrual	4,684	5,478
Purchased Credit Impaired	11,702	15,965
Current	428,521	489,425
Total loans held for investment	451,609	513,994	730,064
Commercial & industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,038,715	1,066,266
Commercial & industrial | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	6,699	15,917
90 Days or More Past Due	0	242
Total loans past due and still accruing	6,699	16,159
Nonaccrual	53,443	45,413
Purchased Credit Impaired	0	0
Current	930,983	941,225
Total loans held for investment	991,125	1,002,797	889,848
Commercial & industrial | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	49	0
90 Days or More Past Due	935	0
Total loans past due and still accruing	984	0
Nonaccrual	1,853	1,901
Purchased Credit Impaired	2,161	3,237
Current	42,592	58,331
Total loans held for investment	47,590	63,469	123,134
Mortgage warehouse
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	185,849	220,230
Mortgage warehouse | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	0
90 Days or More Past Due	0	0
Total loans past due and still accruing	0	0
Nonaccrual	0	0
Purchased Credit Impaired	0	0
Current	185,849	220,230
Total loans held for investment	185,849	220,230
Mortgage warehouse | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	0	0
Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	435,366	415,230
Owner occupied commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	17,703	1,109
90 Days or More Past Due	570	0
Total loans past due and still accruing	18,273	1,109
Nonaccrual	0	0
Purchased Credit Impaired	0	0
Current	333,865	326,797
Total loans held for investment	352,138	327,906	292,413
Owner occupied commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	173	233
90 Days or More Past Due	233	0
Total loans past due and still accruing	406	233
Nonaccrual	1,779	1,886
Purchased Credit Impaired	3,751	4,062
Current	77,292	81,143
Total loans held for investment	83,228	87,324	123,182
Commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,068,832	1,067,779
Commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	11,116	16,250
90 Days or More Past Due	3,110	0
Total loans past due and still accruing	14,226	16,250
Nonaccrual	185	0
Purchased Credit Impaired	0	0
Current	847,276	807,111
Total loans held for investment	861,687	823,361	809,026
Commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	2,317	1,885
90 Days or More Past Due	475	0
Total loans past due and still accruing	2,792	1,885
Nonaccrual	112	312
Purchased Credit Impaired	3,611	6,437
Current	200,630	235,784
Total loans held for investment	207,145	244,418	320,005
Construction, land & land development
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	148,732	164,952
Construction, land & land development | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	2,495	2,255
90 Days or More Past Due	0	133
Total loans past due and still accruing	2,495	2,388
Nonaccrual	3,415	3,287
Purchased Credit Impaired	0	0
Current	116,364	131,323
Total loans held for investment	122,274	136,998	151,114
Construction, land & land development | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	204
90 Days or More Past Due	0	0
Total loans past due and still accruing	0	204
Nonaccrual	709	714
Purchased Credit Impaired	0	0
Current	25,749	27,036
Total loans held for investment	26,458	27,954	50,832
Residential mortgage
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	242,529	238,580
Residential mortgage | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	4,310	1,311
90 Days or More Past Due	0	0
Total loans past due and still accruing	4,310	1,311
Nonaccrual	3,089	3,111
Purchased Credit Impaired	0	0
Current	148,856	144,599
Total loans held for investment	156,255	149,021	130,799
Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	2,431	804
90 Days or More Past Due	89	0
Total loans past due and still accruing	2,520	804
Nonaccrual	16	454
Purchased Credit Impaired	2,179	2,229
Current	81,559	86,072
Total loans held for investment	86,274	89,559	111,040
Consumer and other
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	16,313	17,448
Consumer and other | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	283	127
90 Days or More Past Due	0	0
Total loans past due and still accruing	283	127
Nonaccrual	47	49
Purchased Credit Impaired	0	0
Current	15,069	16,002
Total loans held for investment	15,399	16,178	9,011
Consumer and other | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	0
90 Days or More Past Due	0	0
Total loans past due and still accruing	0	0
Nonaccrual	215	211
Purchased Credit Impaired	0	0
Current	699	1,059
Total loans held for investment	$ 914	$ 1,270	$ 1,871