LOANS AND CREDIT QUALITY - Gross Charge-offs by Year and Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Gross charge-offs, year one	$ 0
Gross charge-offs, year two	(106)
Gross charge-offs, year three	(206)
Gross charge-offs, year four	0
Gross charge-offs, year five	(1,136)
Gross charge-offs, originated more than five years prior, net	291
Revolving	(174)
Revolving-term	(50)
Total	(1,381)	$ (1,266)	$ (2,349)
Commercial business | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Gross charge-offs, year one	0
Gross charge-offs, year two	0
Gross charge-offs, year three	(184)
Gross charge-offs, year four	0
Gross charge-offs, year five	(1,136)
Gross charge-offs, originated more than five years prior, net	295
Revolving, net	13
Revolving-term	(50)
Total	(1,062)	(1,098)	(1,739)
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	(319)	(168)	(610)
Consumer loans | Home equity and other
Financing Receivable, Credit Quality Indicator [Line Items]
Gross charge-offs, year one	0
Gross charge-offs, year two	(106)
Gross charge-offs, year three	(22)
Gross charge-offs, year four	0
Gross charge-offs, year five	0
Gross charge-offs, originated more than five years prior	(4)
Revolving	(187)
Revolving-term	0
Total	$ (319)	$ (168)	$ (483)