LOANS - Age Analysis of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	$ 40,095	$ 20,461
90 Days or More Past Due	375	1,169
Total loans past due and still accruing	40,470	21,630
Nonaccrual	57,338	76,806
Purchased Credit Impaired	15,965	25,188
Current	3,076,712	2,974,596
Total loans held for investment	3,190,485	3,098,220
Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	36,969	11,373
90 Days or More Past Due	375	1,169
Total loans past due and still accruing	37,344	12,542
Nonaccrual	51,860	39,763
Current	2,587,287	2,249,623
Total loans held for investment	2,676,491	2,301,928
Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	3,126	9,088
Total loans past due and still accruing	3,126	9,088
Nonaccrual	5,478	37,043
Purchased Credit Impaired	15,965	25,188
Current	489,425	724,973
Total loans held for investment	513,994	796,292
Commercial & industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,286,496	1,053,925
Commercial & industrial | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	15,917	1,515
90 Days or More Past Due	242	1,106
Total loans past due and still accruing	16,159	2,621
Nonaccrual	45,413	36,331
Current	1,161,455	865,379
Total loans held for investment	1,223,027	904,331
Commercial & industrial | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due		2,854
Total loans past due and still accruing		2,854
Nonaccrual	1,901	23,424
Purchased Credit Impaired	3,237	4,506
Current	58,331	118,810
Total loans held for investment	63,469	149,594
Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	415,230	394,210
Owner occupied commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	1,109	1,941
Total loans past due and still accruing	1,109	1,941
Current	326,797	262,935
Total loans held for investment	327,906	264,876
Owner occupied commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	233	223
Total loans past due and still accruing	233	223
Nonaccrual	1,886	8,942
Purchased Credit Impaired	4,062	5,339
Current	81,143	114,830
Total loans held for investment	87,324	129,334
Commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,067,779	1,143,751
Commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	16,250	1,612
Total loans past due and still accruing	16,250	1,612
Nonaccrual		2,059
Current	807,111	812,358
Total loans held for investment	823,361	816,029
Commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	1,885	2,529
Total loans past due and still accruing	1,885	2,529
Nonaccrual	312	2,002
Purchased Credit Impaired	6,437	10,807
Current	235,784	312,384
Total loans held for investment	244,418	327,722
Construction, land & land development
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	164,952	249,704
Construction, land & land development | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	2,255	4,375
90 Days or More Past Due	133
Total loans past due and still accruing	2,388	4,375
Nonaccrual	3,287
Current	131,323	175,624
Total loans held for investment	136,998	179,999
Construction, land & land development | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	204	488
Total loans past due and still accruing	204	488
Nonaccrual	714	978
Purchased Credit Impaired		1,819
Current	27,036	66,420
Total loans held for investment	27,954	69,705
Residential mortgage
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	238,580	245,191
Residential mortgage | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	1,311	1,791
90 Days or More Past Due		63
Total loans past due and still accruing	1,311	1,854
Nonaccrual	3,111	1,254
Current	144,599	124,337
Total loans held for investment	149,021	127,445
Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	804	2,768
Total loans past due and still accruing	804	2,768
Nonaccrual	454	1,692
Purchased Credit Impaired	2,229	2,717
Current	86,072	110,569
Total loans held for investment	89,559	117,746
Consumer and other
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	17,448	11,439
Consumer and other | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	127	139
Total loans past due and still accruing	127	139
Nonaccrual	49	119
Current	16,002	8,990
Total loans held for investment	16,178	9,248
Consumer and other | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due		226
Total loans past due and still accruing		226
Nonaccrual	211	5
Current	1,059	1,960
Total loans held for investment	$ 1,270	$ 2,191