LOANS (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Activity in the allowance for loan losses
Balance at end of year	$ 33,263	$ 33,208
Allowance For Loan Losses
Total	33,263	33,208
Loans receivable: Balance at end of year
Total loans	3,889,072	3,988,654
Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	31,891	31,898
Charged-off loans	1,839	9,067
Recoveries on charged-off loans	126	416
Provision for loan losses	1,862	8,644
Balance at end of year	32,040	31,891
Allowance For Loan Losses
Individually evaluated for impairment	3,235	3,264
Collectively evaluated for impairment	28,805	28,627
Total	32,040	31,891
Loans receivable: Balance at end of year
Individually evaluated for impairment	41,059	40,688
Collectively evaluated for impairment	2,575,099	2,584,948
Total loans	2,616,158	2,625,636
Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	1,317	546
Charged-off loans	662	383
Recoveries on charged-off loans	30	208
Provision for loan losses	538	946
Balance at end of year	1,223	1,317
Allowance For Loan Losses
Individually evaluated for impairment	113	55
Collectively evaluated for impairment	1,110	1,262
Total	1,223	1,317
Loans receivable: Balance at end of year
Individually evaluated for impairment	3,509	1,257
Collectively evaluated for impairment	1,269,405	1,361,761
Total loans	1,272,914	1,363,018
Residential mortgages
Loans receivable: Balance at end of year
Total loans	1,234,616	1,324,251
Residential mortgages | Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	5,928	3,150
Charged-off loans	190	2,604
Recoveries on charged-off loans	16	103
Provision for loan losses	244	5,279
Balance at end of year	5,998	5,928
Allowance For Loan Losses
Individually evaluated for impairment	765	342
Collectively evaluated for impairment	5,233	5,586
Total	5,998	5,928
Loans receivable: Balance at end of year
Individually evaluated for impairment	7,625	6,362
Collectively evaluated for impairment	824,041	884,304
Total loans	831,666	890,666
Residential mortgages | Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	509	281
Charged-off loans	86	43
Provision for loan losses	95	271
Balance at end of year	518	509
Allowance For Loan Losses
Individually evaluated for impairment	113	55
Collectively evaluated for impairment	405	454
Total	518	509
Loans receivable: Balance at end of year
Individually evaluated for impairment	954	371
Collectively evaluated for impairment	401,996	433,214
Total loans	402,950	433,585
Commercial mortgages
Loans receivable: Balance at end of year
Total loans	1,397,142	1,413,544
Commercial mortgages | Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	18,863	22,095
Charged-off loans	720	4,229
Recoveries on charged-off loans	3	52
Provision for loan losses	402	945
Balance at end of year	18,548	18,863
Allowance For Loan Losses
Individually evaluated for impairment	1,374	1,444
Collectively evaluated for impairment	17,174	17,419
Total	18,548	18,863
Loans receivable: Balance at end of year
Individually evaluated for impairment	30,024	30,287
Collectively evaluated for impairment	939,189	932,606
Total loans	969,213	962,893
Commercial mortgages | Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	390	158
Charged-off loans	235
Provision for loan losses	265	232
Balance at end of year	420	390
Allowance For Loan Losses
Collectively evaluated for impairment	420	390
Total	420	390
Loans receivable: Balance at end of year
Individually evaluated for impairment	2,374	886
Collectively evaluated for impairment	425,555	449,765
Total loans	427,929	450,651
Commercial business loans
Loans receivable: Balance at end of year
Total loans	618,342	600,126
Commercial business loans | Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	5,605	4,540
Charged-off loans	679	697
Recoveries on charged-off loans	71	96
Provision for loan losses	194	1,666
Balance at end of year	5,191	5,605
Allowance For Loan Losses
Individually evaluated for impairment	824	1,205
Collectively evaluated for impairment	4,367	4,400
Total	5,191	5,605
Loans receivable: Balance at end of year
Individually evaluated for impairment	1,900	2,821
Collectively evaluated for impairment	515,789	487,106
Total loans	517,689	489,927
Commercial business loans | Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	96	38
Charged-off loans	25
Recoveries on charged-off loans	2
Provision for loan losses	27	58
Balance at end of year	100	96
Allowance For Loan Losses
Collectively evaluated for impairment	100	96
Total	100	96
Loans receivable: Balance at end of year
Individually evaluated for impairment	181
Collectively evaluated for impairment	100,472	110,199
Total loans	100,653	110,199
Consumer loans
Loans receivable: Balance at end of year
Total loans	638,972	650,733
Consumer loans | Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	1,466	2,203
Charged-off loans	250	1,537
Recoveries on charged-off loans	36	165
Provision for loan losses	874	635
Balance at end of year	2,126	1,466
Allowance For Loan Losses
Individually evaluated for impairment	272	273
Collectively evaluated for impairment	1,854	1,193
Total	2,126	1,466
Loans receivable: Balance at end of year
Individually evaluated for impairment	1,510	1,218
Collectively evaluated for impairment	296,080	280,932
Total loans	297,590	282,150
Consumer loans | Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	314	87
Charged-off loans	316	340
Recoveries on charged-off loans	28	208
Provision for loan losses	307	359
Balance at end of year	333	314
Allowance For Loan Losses
Collectively evaluated for impairment	333	314
Total	333	314
Loans receivable: Balance at end of year
Collectively evaluated for impairment	341,382	368,583
Total loans	341,382	368,583
Unallocated | Business Loans
Activity in the allowance for loan losses
Balance at beginning of year	29	(90)
Provision for loan losses	148	119
Balance at end of year	177	29
Allowance For Loan Losses
Collectively evaluated for impairment	177	29
Total	177	29
Unallocated | Acquired Loans
Activity in the allowance for loan losses
Balance at beginning of year	8	(18)
Provision for loan losses	(156)	26
Balance at end of year	(148)	8
Allowance For Loan Losses
Collectively evaluated for impairment	(148)	8
Total	$ (148)	$ 8