LOANS AND ALLOWANCE FOR LOAN LOSSES (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 23,044	$ 23,011	$ 23,011
Loans charged off	(587)	(1,089)	(4,502)
Recoveries	228	97	744
Provision (reduction)	684	991	3,791
Ending balance	23,369	23,010	23,044
Ending Balance: Individually evaluated for impairment	3,541	1,800	3,106
Ending Balance: Collectively evaluated for impairment	19,828	21,210	19,938
Ending Balance: Individually evaluated for impairment	27,059	12,839	27,157
Ending Balance: Collectively evaluated for impairment	1,551,108	1,503,342	1,536,709
Loans ending balance	1,578,167	1,516,181	1,563,866
Residential real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,996	6,398	6,398
Loans charged off	(145)	(308)	(1,197)
Recoveries	3	5	73
Provision (reduction)	415	8	1,722
Ending balance	7,269	6,103	6,996
Ending Balance: Individually evaluated for impairment	2,468	754	2,255
Ending Balance: Collectively evaluated for impairment	4,801	5,349	4,741
Ending Balance: Individually evaluated for impairment	13,754	7,039	13,805
Ending Balance: Collectively evaluated for impairment	558,180	566,245	558,368
Loans ending balance	571,934	573,284	572,173
Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	4,549	5,702	5,702
Loans charged off	(80)	(179)	(593)
Recoveries	75	21	222
Provision (reduction)	(942)	169	(782)
Ending balance	3,602	5,713	4,549
Ending Balance: Individually evaluated for impairment	197	479	265
Ending Balance: Collectively evaluated for impairment	3,405	5,234	4,284
Ending Balance: Individually evaluated for impairment	7,633	4,058	7,968
Ending Balance: Collectively evaluated for impairment	498,359	476,004	498,263
Loans ending balance	505,992	480,062	506,231
Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,933	4,846	4,846
Loans charged off	(277)	(191)	(1,393)
Recoveries	129	64	406
Provision (reduction)	415	474	2,074
Ending balance	6,200	5,193	5,933
Ending Balance: Individually evaluated for impairment	325	567	286
Ending Balance: Collectively evaluated for impairment	5,875	4,626	5,647
Ending Balance: Individually evaluated for impairment	3,329	866	3,610
Ending Balance: Collectively evaluated for impairment	187,963	178,931	186,844
Loans ending balance	191,292	179,797	190,454
Home equity loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,520	2,704	2,704
Loans charged off	(28)	(387)	(1,234)
Recoveries	2		23
Provision (reduction)	864	157	1,027
Ending balance	3,358	2,474	2,520
Ending Balance: Individually evaluated for impairment	469		261
Ending Balance: Collectively evaluated for impairment	2,889	2,474	2,259
Ending Balance: Individually evaluated for impairment	1,855	868	1,515
Ending Balance: Collectively evaluated for impairment	289,835	269,454	276,860
Loans ending balance	291,690	270,322	278,375
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	184	420	420
Loans charged off	(57)	(24)	(85)
Recoveries	19	7	20
Provision (reduction)	76	120	(171)
Ending balance	222	523	184
Ending Balance: Individually evaluated for impairment	82		39
Ending Balance: Collectively evaluated for impairment	140	523	145
Ending Balance: Individually evaluated for impairment	488	8	259
Ending Balance: Collectively evaluated for impairment	16,771	12,708	16,374
Loans ending balance	17,259	12,716	16,633
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,862	2,941	2,941
Loans charged off
Recoveries
Provision (reduction)	(144)	63	(79)
Ending balance	2,718	3,004	2,862
Ending Balance: Individually evaluated for impairment
Ending Balance: Collectively evaluated for impairment	2,718	3,004	2,862
Ending Balance: Individually evaluated for impairment
Ending Balance: Collectively evaluated for impairment
Loans ending balance