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INVESTMENT SECURITIES - Narrative (Details) - USD ($)	3 Months Ended
INVESTMENT SECURITIES - Narrative (Details) - USD ($)	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Gross sales of available-for-sale securities	$ 0	$ 10,841,000
Gross gains on sale of available-for-sale securities		157,000
Gross losses on sale of available-for-sale securities		$ 1,000
Federal Reserve Bank
Debt Securities, Available-for-sale [Line Items]
Borrowings outstanding under line of credit facility	0		$ 0
U.S. government agency obligations \| Asset Pledged as Collateral \| Specific Municipal Deposits
Debt Securities, Available-for-sale [Line Items]
Securities pledged as collateral	548,000		576,000
Mortgage-backed securities \| MPF Credit Enhancement Fee
Debt Securities, Available-for-sale [Line Items]
Securities pledged as collateral	402,000		468,000
Mortgage-backed securities \| Asset Pledged as Collateral \| Specific Municipal Deposits
Debt Securities, Available-for-sale [Line Items]
Securities pledged as collateral	2,655,000		3,028,000
Mortgage-backed securities \| Asset Pledged as Collateral \| Federal Reserve Bank
Debt Securities, Available-for-sale [Line Items]
Securities pledged as collateral	$ 1,121,000		$ 1,209,000