LOANS, Loan Summary (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Loans receivable, net [Abstract]
Typical contract term of consumer mortgages, minimum	10 years
Typical contract term of consumer mortgages, maximum	30 years
Typical contract term of home equity loans, maximum	30 years
Gross loans, including deferred origination costs	$ 4,147,803,000		$ 4,109,083,000
Allowance for loan losses	(44,615,000)	(44,197,000)	(44,319,000)	(43,473,000)	(42,913,000)	(42,888,000)
Net loans	4,103,188,000		4,064,764,000
Credit impaired acquired loans, outstanding balance	13,400,000		15,500,000
Accretable discount related to credit impaired acquired loans [Roll forward]
Beginning Balance	997,000
Accretion recognized, year-to-date	(384,000)
Net reclassification to accretable from nonaccretable	120,000
Ending Balance	733,000
Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,580,584,000		1,582,058,000
Allowance for loan losses	(9,375,000)	(9,281,000)	(8,994,000)	(7,373,000)	(7,292,000)	(7,070,000)
Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,247,129,000		1,260,364,000
Allowance for loan losses	(16,553,000)	(17,046,000)	(17,507,000)	(18,283,000)	(17,557,000)	(18,013,000)
Consumer Indirect [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	797,297,000		740,002,000
Allowance for loan losses	(11,354,000)	(10,586,000)	(10,248,000)	(9,369,000)	(9,448,000)	(9,606,000)
Consumer Direct [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	183,448,000		180,139,000
Allowance for loan losses	(3,298,000)	(3,087,000)	(3,181,000)	(3,054,000)	(3,084,000)	(3,303,000)
Home Equity [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	339,345,000		346,520,000
Allowance for loan losses	$ (1,860,000)	$ (1,818,000)	$ (1,830,000)	$ (1,674,000)	$ (1,683,000)	$ (1,451,000)