LOANS, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for loan losses [Roll Forward]
Beginning balance	$ 47,451	$ 46,526	$ 47,233	$ 45,401
Charge-offs	(3,224)	(2,924)	(9,447)	(8,561)
Recoveries	1,442	1,397	4,594	4,513
Provision	2,314	1,790	5,603	5,436
Ending balance	47,983	46,789	47,983	46,789
Acquired Impaired [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	63	139	108	168
Charge-offs	0	0	(184)	(26)
Recoveries	0	0	0	0
Provision	(11)	0	128	(3)
Ending balance	52	139	52	139
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	10,197	9,853	10,094	10,198
Charge-offs	(198)	(202)	(541)	(445)
Recoveries	24	12	42	96
Provision	280	305	708	119
Ending balance	10,303	9,968	10,303	9,968
Commercial Portfolio Segment [Member] | Business Lending [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	17,230	16,949	17,220	15,749
Charge-offs	(124)	(284)	(1,062)	(1,263)
Recoveries	127	220	481	511
Provision	399	(283)	993	1,605
Ending balance	17,632	16,602	17,632	16,602
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	13,918	13,215	13,782	12,422
Charge-offs	(2,328)	(2,037)	(5,969)	(5,439)
Recoveries	1,058	892	3,379	3,146
Provision	1,130	1,503	2,586	3,444
Ending balance	13,778	13,573	13,778	13,573
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	2,945	3,020	2,979	2,997
Charge-offs	(574)	(395)	(1,463)	(1,246)
Recoveries	221	246	648	705
Provision	426	170	854	585
Ending balance	3,018	3,041	3,018	3,041
Consumer Portfolio Segment [Member] | Home Equity [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	2,242	2,500	2,399	2,666
Charge-offs	0	(6)	(228)	(142)
Recoveries	12	27	44	55
Provision	(52)	10	(13)	(48)
Ending balance	2,202	2,531	2,202	2,531
Unallocated Financing Receivables [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	856	850	651	1,201
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	142	85	347	(266)
Ending balance	$ 998	$ 935	$ 998	$ 935