BALANCE SHEET OFFSETTING (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Offsetting Assets [Line Items]
Derivative Asset, Not Offset, Policy Election Deduction	$ 0	$ 0
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Gross	7,722	7,871
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Liability	0	0
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed	7,722	7,871
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Not Offset, Policy Election Deduction	0	0
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Collateral, Obligation to Return Cash	0	(4,404)
Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Amount Offset Against Collateral	7,722	3,467
Derivative Liability, Not Offset, Policy Election Deduction	0	0
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Gross	14,433	13,523
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Asset	0	0
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned	14,433	13,523
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Not Offset, Policy Election Deduction	0	0
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Cash	11,113	5,682
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Amount Offset Against Collateral	3,320	7,841
Securities Sold under Agreements to Repurchase, Gross	256,181	245,868
Securities Sold under Agreements to Repurchase, Asset	0	0
Securities Sold under Agreements to Repurchase	256,181	245,868
Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Securities	256,181	245,868
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	0	0
Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral	0	0
Customer Loan Swap Dealer Bank [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset		4,374
Derivative Asset, Fair Value, Gross Liability		0
Derivative Asset		4,374
Derivative, Collateral, Obligation to Return Cash		(4,374)
Derivative Asset, Fair Value, Amount Offset Against Collateral		0
Derivative Liability, Fair Value, Gross Liability	4,402
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability	4,402
Derivative Liability, Not Offset, Policy Election Deduction	0
Derivative, Collateral, Right to Reclaim Cash	4,402
Derivative Liability, Fair Value, Amount Offset Against Collateral	0
Customer Loan Swaps Commercial Customer [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,722	3,467
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset	7,722	3,467
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	7,722	3,467
Derivative Liability, Fair Value, Gross Liability	3,320	7,841
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability	3,320	7,841
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	3,320	7,841
FHLBB Advance Interest Rate Swap [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset		30
Derivative Asset, Fair Value, Gross Liability		0
Derivative Asset		30
Derivative, Collateral, Obligation to Return Cash		(30)
Derivative Asset, Fair Value, Amount Offset Against Collateral		0
Junior Subordinated Debt Interest Rate Swap [Member]
Offsetting Assets [Line Items]
Derivative Liability, Fair Value, Gross Liability	6,711	5,682
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability	6,711	5,682
Derivative, Collateral, Right to Reclaim Cash	6,711	5,682
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 0	$ 0