ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) loan	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan workout and other credit costs	$ 1,071,000	$ (55,000)
Various Modifications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unused commitments to extend credit	19,200,000		$ 18,400,000
Loans Modified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans modified with subsequent default	$ 8,893,000	0
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans in the process of foreclosure | loan	32		31
Total loans outstanding	$ 6,300,000		$ 3,200,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans in the process of foreclosure | loan	11		9
Total loans outstanding	$ 1,300,000		$ 1,100,000
Residential and Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan workout and other credit costs	$ (400,000)	$ 200,000
Impairment loans, charge off period	90 days