LOANS AND ALLOWANCE FOR LOAN LOSSES- Activity in Allowance for Loan Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Allowance for loan losses:
Beginning balance	$ 1,081	$ 7,043	$ 3,998
Charge-offs	(2,749)	(3,141)	(2,721)
Recoveries	312	502	297
Provision for loan losses	5,354	3,413	5,469
Ending balance		7,817	7,043
Ending balance:
Individually evaluated for impairment		390	652
Collectively evaluated for impairment		6,129	4,030
Purchased credit-impaired		1,298	2,361
Total		7,817	7,043
Ending balance:
Individually evaluated for impairment		9,985	8,916
Collectively evaluated for impairment		2,682,925	1,204,370
Purchased credit-impaired		206,127	180,035
Total		2,899,037	1,393,321
Commercial real estate
Allowance for loan losses:
Beginning balance	457	2,419	1,524
Charge-offs	0	(366)	(20)
Recoveries	0	46	26
Provision for loan losses	1,067	697	889
Ending balance		2,796	2,419
Ending balance:
Individually evaluated for impairment		158	57
Collectively evaluated for impairment		2,177	1,322
Purchased credit-impaired		461	1,040
Total		2,796	2,419
Ending balance:
Individually evaluated for impairment		5,398	4,590
Collectively evaluated for impairment		1,227,597	562,081
Purchased credit-impaired		122,541	103,622
Total		1,355,536	670,293
Commercial and industrial
Allowance for loan losses:
Beginning balance	197	805	798
Charge-offs	(250)	(1,034)	(483)
Recoveries	19	88	23
Provision for loan losses	832	1,415	467
Ending balance		1,274	805
Ending balance:
Individually evaluated for impairment		229	323
Collectively evaluated for impairment		952	482
Purchased credit-impaired		93	0
Total		1,274	805
Ending balance:
Individually evaluated for impairment		2,343	343
Collectively evaluated for impairment		452,487	219,251
Purchased credit-impaired		14,018	11,020
Total		468,848	230,614
Commercial Construction
Allowance for loan losses:
Beginning balance	207	1,400	597
Charge-offs	(400)	(367)	(723)
Recoveries	125	69	47
Provision for loan losses	665	589	1,479
Ending balance		1,691	1,400
Ending balance:
Individually evaluated for impairment		0	0
Collectively evaluated for impairment		1,590	1,139
Purchased credit-impaired		101	261
Total		1,691	1,400
Ending balance:
Individually evaluated for impairment		910	2,609
Collectively evaluated for impairment		337,540	137,911
Purchased credit-impaired		32,357	35,274
Total		370,807	175,794
Residential real estate
Allowance for loan losses:
Beginning balance	128	1,673	940
Charge-offs	(341)	(591)	(672)
Recoveries	153	131	146
Provision for loan losses	1,000	24	1,259
Ending balance		1,237	1,673
Ending balance:
Individually evaluated for impairment		0	0
Collectively evaluated for impairment		681	688
Purchased credit-impaired		556	985
Total		1,237	1,673
Ending balance:
Individually evaluated for impairment		928	695
Collectively evaluated for impairment		328,693	164,106
Purchased credit-impaired		30,628	26,577
Total		360,249	191,378
Construction and development
Allowance for loan losses:
Beginning balance	28	187	18
Charge-offs	(15)	0	0
Recoveries	0	0	0
Provision for loan losses	5	7	169
Ending balance		194	187
Ending balance:
Individually evaluated for impairment		0	0
Collectively evaluated for impairment		194	187
Purchased credit-impaired		0	0
Total		194	187
Ending balance:
Individually evaluated for impairment		0	242
Collectively evaluated for impairment		28,436	20,447
Purchased credit-impaired		1,625	1,831
Total		30,061	22,520
Home equity
Allowance for loan losses:
Beginning balance	51	476	85
Charge-offs	(1,596)	(429)	(558)
Recoveries	6	123	39
Provision for loan losses	1,624	376	910
Ending balance		546	476
Ending balance:
Individually evaluated for impairment		3	270
Collectively evaluated for impairment		456	153
Purchased credit-impaired		87	53
Total		546	476
Ending balance:
Individually evaluated for impairment		406	424
Collectively evaluated for impairment		271,928	92,592
Purchased credit-impaired		4,328	1,374
Total		276,662	94,390
Other consumer
Allowance for loan losses:
Beginning balance	13	83	36
Charge-offs	(147)	(354)	(265)
Recoveries	9	45	16
Provision for loan losses	161	305	296
Ending balance		79	83
Ending balance:
Individually evaluated for impairment		0	2
Collectively evaluated for impairment		79	59
Purchased credit-impaired		0	22
Total		79	83
Ending balance:
Individually evaluated for impairment		0	13
Collectively evaluated for impairment		36,244	7,982
Purchased credit-impaired		630	337
Total		$ 36,874	$ 8,332