SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE AND OTHER SHORT-TERM DEBT -Borrowing Capacity and Loans Pledged (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE AND OTHER SHORT-TERM DEBT
Borrowing capacity through unsecured borrowing lines	$ 55,000
Loans pledged to the FHLBB	363,550	$ 371,580
Additional short or long-term borrowing capacity with FHLBB	256,980	262,960
Proceeds from debt issuance	62,060	17,810
Remaining borrowing capacity	$ 194,920	$ 245,150