BORROWINGS (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Assets pledged as collateral against borrowings	$ 3,000,000,000	$ 2,600,000,000
Interest expense on short-term borrowings	984,000	2,300,000	5,000,000
Interest expense on long-term borrowings	11,700,000	13,000,000	13,500,000
Federal home loan bank unused remaining available borrowing capacity	661,900,000	526,600,000
Federal Home Loan Bank [Member]
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity	5,000,000
Federal Reserve Bank of Boston [Member]
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity	766,200,000	618,800,000
Line of credit amount outstanding	0	0
Swap [Member]
Debt Instrument [Line Items]
FHLB advances amount hedged	$ 150,000,000
Derivative weighted average interest rate	2.66%