LOANS, Loan Summary (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Loans receivable, net [Abstract]
Contract term of consumer mortgages, minimum (in years)	15 years
Contract term of consumer mortgages, maximum (in years)	30 years
Contract term of home equity loans, maximum (in years)	15 years
Gross loans, including deferred origination costs	$ 3,861,601,000	$ 3,865,576,000
Allowance for loan losses	(42,913,000)	(42,888,000)	(41,809,000)	(42,213,000)
Net loans	3,818,688,000	3,822,688,000
Credit impaired acquired loans, outstanding balance	21,900,000	22,400,000
Accretable discount related to acquired loans [Roll forward]
Beginning Balance	1,770,000
Accretion recognized, to-date	(264,000)
Net reclassification from accretable to nonaccretable	35,000
Ending Balance	1,541,000
Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,480,192,000	1,448,415,000
Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,222,835,000	1,233,944,000
Consumer Indirect [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	639,560,000	647,518,000
Consumer Direct [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	165,649,000	171,474,000
Home Equity [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 353,365,000	$ 364,225,000