LOANS - Age Analysis of Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	$ 35,902	$ 40,095
90 Days or More Past Due	907	375
Total loans past due and still accruing	36,809	40,470
Nonaccrual	54,829	57,338
Purchased Credit Impaired	10,717	15,965
Current	3,119,753	3,076,712
Total loans held for investment	3,222,108	3,190,485	$ 3,123,355
Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	20,321	36,969
90 Days or More Past Due	85	375
Total loans past due and still accruing	20,406	37,344
Nonaccrual	50,444	51,860
Purchased Credit Impaired	0	0
Current	2,808,114	2,587,287
Total loans held for investment	2,878,964	2,676,491	2,476,754
Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	15,581	3,126
90 Days or More Past Due	822	0
Total loans past due and still accruing	16,403	3,126
Nonaccrual	4,385	5,478
Purchased Credit Impaired	10,717	15,965
Current	311,639	489,425
Total loans held for investment	343,144	513,994	646,601
Commercial & industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,070,420	1,066,266
Commercial & industrial | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	4,396	15,917
90 Days or More Past Due	0	242
Total loans past due and still accruing	4,396	16,159
Nonaccrual	41,033	45,413
Purchased Credit Impaired	0	0
Current	989,392	941,225
Total loans held for investment	1,034,821	1,002,797
Commercial & industrial | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	4,310	0
90 Days or More Past Due	438	0
Total loans past due and still accruing	4,748	0
Nonaccrual	1,746	1,901
Purchased Credit Impaired	1,730	3,237
Current	27,375	58,331
Total loans held for investment	35,599	63,469	91,978
Mortgage warehouse
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	244,041	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	244,041	220,230
Total loans held for investment	244,041	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	436,153	415,230
Owner occupied commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	1,109
90 Days or More Past Due	0	0
Total loans past due and still accruing	0	1,109
Nonaccrual	5,225	0
Purchased Credit Impaired	0	0
Current	368,467	326,797
Total loans held for investment	373,692	327,906	306,514
Owner occupied commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	1,837	233
90 Days or More Past Due	0	0
Total loans past due and still accruing	1,837	233
Nonaccrual	1,727	1,886
Purchased Credit Impaired	3,394	4,062
Current	55,503	81,143
Total loans held for investment	62,461	87,324	100,803
Commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	1,092,036	1,067,779
Commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	14,800	16,250
90 Days or More Past Due	0	0
Total loans past due and still accruing	14,800	16,250
Nonaccrual	175	0
Purchased Credit Impaired	0	0
Current	934,124	807,111
Total loans held for investment	949,099	823,361	807,341
Commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	8,290	1,885
90 Days or More Past Due	268	0
Total loans past due and still accruing	8,558	1,885
Nonaccrual	105	312
Purchased Credit Impaired	3,591	6,437
Current	130,683	235,784
Total loans held for investment	142,937	244,418	301,896
Construction, land & land development
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	130,533	164,952
Construction, land & land development | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	2,255
90 Days or More Past Due	0	133
Total loans past due and still accruing	0	2,388
Nonaccrual	107	3,287
Purchased Credit Impaired	0	0
Current	105,819	131,323
Total loans held for investment	105,926	136,998	153,522
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	700	714
Purchased Credit Impaired	0	0
Current	23,907	27,036
Total loans held for investment	24,607	27,954	48,470
Residential mortgage
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	235,192	238,580
Residential mortgage | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	968	1,311
90 Days or More Past Due	59	0
Total loans past due and still accruing	1,027	1,311
Nonaccrual	3,859	3,111
Purchased Credit Impaired	0	0
Current	153,645	144,599
Total loans held for investment	158,531	149,021	137,918
Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	1,144	804
90 Days or More Past Due	97	0
Total loans past due and still accruing	1,241	804
Nonaccrual	104	454
Purchased Credit Impaired	2,002	2,229
Current	73,314	86,072
Total loans held for investment	76,661	89,559	101,916
Consumer and other
Financing Receivable, Recorded Investment, Aging [Abstract]
Total loans held for investment	13,733	17,448
Consumer and other | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	157	127
90 Days or More Past Due	26	0
Total loans past due and still accruing	183	127
Nonaccrual	45	49
Purchased Credit Impaired	0	0
Current	12,626	16,002
Total loans held for investment	12,854	16,178	19,105
Consumer and other | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30 - 89 Days Past Due	0	0
90 Days or More Past Due	19	0
Total loans past due and still accruing	19	0
Nonaccrual	3	211
Purchased Credit Impaired	0	0
Current	857	1,059
Total loans held for investment	$ 879	$ 1,270	$ 1,538