LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 4) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015
Allowance for loan losses
Beginning balance	$ 9,769	$ 7,817
Charge-offs	(1,633)	(765)
Recoveries	220	271
Provision for loan losses	1,875	961
Ending balance	10,231	8,284
Ending balance:
Individually evaluated for impairment			$ 423	$ 487
Collectively evaluated for impairment			9,030	7,960
Total	9,769	7,817	10,231	9,769
Ending balance:
Individually evaluated for impairment			12,728	15,553
Collectively evaluated for impairment			4,974,029	2,920,061
Purchased credit-impaired			223,207	142,042
Total			5,209,964	3,077,656
Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	1,322
Ending balance	778
Ending balance:
Total	1,322		778	1,322
Commercial real estate
Allowance for loan losses
Beginning balance	3,682	2,796
Charge-offs	(81)	(99)
Recoveries	4	5
Provision for loan losses	(148)	252
Ending balance	3,457	2,954
Ending balance:
Individually evaluated for impairment			350	314
Collectively evaluated for impairment			2,706	2,976
Total	3,682	2,796	3,457	3,682
Ending balance:
Individually evaluated for impairment			8,511	8,449
Collectively evaluated for impairment			2,262,642	1,354,977
Purchased credit-impaired			98,165	87,750
Total			2,369,318	1,451,176
Commercial real estate | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	392
Ending balance	401
Ending balance:
Total	392		401	392
Commercial and industrial
Allowance for loan losses
Beginning balance	2,431	1,274
Charge-offs	(961)	(369)
Recoveries	4	136
Provision for loan losses	1,798	295
Ending balance	3,272	1,336
Ending balance:
Individually evaluated for impairment			15	106
Collectively evaluated for impairment			3,246	2,309
Total	2,431	1,274	3,272	2,431
Ending balance:
Individually evaluated for impairment			2,302	2,623
Collectively evaluated for impairment			804,626	540,685
Purchased credit-impaired			21,135	9,813
Total			828,063	553,121
Commercial and industrial | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	16
Ending balance	11
Ending balance:
Total	16		11	16
Construction and development
Allowance for loan losses
Beginning balance	866	1,691
Charge-offs	(17)	(16)
Recoveries	11	5
Provision for loan losses	(67)	52
Ending balance	793	1,732
Ending balance:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			780	704
Total	866	1,691	793	866
Ending balance:
Individually evaluated for impairment			234	177
Collectively evaluated for impairment			365,347	330,714
Purchased credit-impaired			14,666	14,413
Total			380,247	345,304
Construction and development | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	162
Ending balance	13
Ending balance:
Total	162		13	162
Residential real estate
Allowance for loan losses
Beginning balance	1,257	1,237
Charge-offs	(160)	(10)
Recoveries	182	24
Provision for loan losses	(288)	0
Ending balance	991	1,251
Ending balance:
Individually evaluated for impairment			58	0
Collectively evaluated for impairment			800	837
Total	1,257	1,237	991	1,257
Ending balance:
Individually evaluated for impairment			1,681	3,550
Collectively evaluated for impairment			658,216	315,030
Purchased credit-impaired			66,693	25,068
Total			726,590	343,648
Residential real estate | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	420
Ending balance	133
Ending balance:
Total	420		133	420
Construction and development
Allowance for loan losses
Beginning balance	237	194
Charge-offs	0	0
Recoveries	0	27
Provision for loan losses	19	(8)
Ending balance	256	213
Ending balance:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			253	233
Total	237	194	256	237
Ending balance:
Individually evaluated for impairment			0	417
Collectively evaluated for impairment			286,362	44,630
Purchased credit-impaired			2,933	1,216
Total			289,295	46,263
Construction and development | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	4
Ending balance	3
Ending balance:
Total	4		3	4
Home equity
Allowance for loan losses
Beginning balance	883	546
Charge-offs	(197)	(135)
Recoveries	0	41
Provision for loan losses	333	254
Ending balance	1,019	706
Ending balance:
Individually evaluated for impairment			0	67
Collectively evaluated for impairment			823	542
Total	883	546	1,019	883
Ending balance:
Individually evaluated for impairment			0	337
Collectively evaluated for impairment			519,707	274,042
Purchased credit-impaired			18,817	3,521
Total			538,524	277,900
Home equity | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	274
Ending balance	196
Ending balance:
Total	274		196	274
Other consumer
Allowance for loan losses
Beginning balance	413	79
Charge-offs	(217)	(136)
Recoveries	19	33
Provision for loan losses	228	116
Ending balance	443	92
Ending balance:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			422	359
Total	413	$ 79	443	413
Ending balance:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			77,129	59,983
Purchased credit-impaired			798	261
Total			77,927	60,244
Other consumer | Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Beginning balance	54
Ending balance	21
Ending balance:
Total	$ 54		$ 21	$ 54