BORROWINGS (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Repurchase Agreements	$ 265,997	$ 237,984
Total short-term borrowings	326,722	268,809
Long-term Federal Home Loan Bank Advances	35,000	10,000
Total long-term borrowings	35,000	10,000
Short-term Debt [Member]
Debt Instrument [Line Items]
Repurchase Agreements	265,997	237,984
FHLBB advances less than 90 days	50,000	25,000
FHLBB and Correspondent Bank Overnight Borrowings	$ 10,725	$ 5,825