LOANS, Loan Summary (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 4,236,206,000	$ 4,109,083,000
Allowance for loan losses	(45,341,000)	(44,319,000)	(42,888,000)
Net loans	4,190,865,000	4,064,764,000
Net deferred loan origination costs	18,700,000	18,500,000
Loans receivable, related parties [Roll Forward]
Balance at beginning of year	9,448,000	8,292,000
New loans	1,647,000	3,643,000
Payments	(2,167,000)	(2,487,000)
Balance at end of year	8,928,000	9,448,000
Credit impaired acquired loans [Abstract]
Outstanding principal balance	5,957,000	11,457,000
Carrying amount	5,312,000	7,090,000
Credit impaired acquired loans, total balance due	6,100,000	13,100,000
Non-impaired acquired loans [Abstract]
Outstanding principal balance	276,584,000	342,542,000
Carrying amount	267,496,000	330,118,000
Total acquired loans [Abstract]
Outstanding principal balance	282,541,000	353,999,000
Carrying amount	272,808,000	337,208,000
Accretable discount related to acquired loans [Roll forward]
Balance at beginning of year	997,000	1,770,000
Accretion recognized	(707,000)	(1,025,000)
Net reclassification to accretable from nonaccretable	415,000	252,000
Balance at end of year	705,000	997,000
Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,613,384,000	1,582,058,000
Allowance for loan losses	(10,286,000)	(8,994,000)	(7,070,000)
Consumer Mortgage [Member] | Minimum [Member]
Loans receivable, net [Abstract]
Contract term of loans	10 years
Consumer Mortgage [Member] | Maximum [Member]
Loans receivable, net [Abstract]
Contract term of loans	30 years
Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,262,484,000	1,260,364,000
Allowance for loan losses	(15,787,000)	(17,507,000)	(18,013,000)
Consumer Indirect [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	833,968,000	740,002,000
Allowance for loan losses	(11,544,000)	(10,248,000)	(9,606,000)
Consumer Direct [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	184,028,000	180,139,000
Allowance for loan losses	(3,083,000)	(3,181,000)	(3,303,000)
Home Equity [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	342,342,000	346,520,000
Allowance for loan losses	$ (2,701,000)	$ (1,830,000)	$ (1,451,000)
Home Equity [Member] | Maximum [Member]
Loans receivable, net [Abstract]
Contract term of loans	30 years