LOANS AND CREDIT QUALITY - Gross Charge-offs by Year and Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, year one, Gross charge-offs			$ 0		$ 0
Financing receivable, year two, Gross charge-offs			(24)		(106)
Financing receivable, year three, Gross charge-offs			(5)		(206)
Financing receivable, year four, Gross charge-offs			(458)		0
Financing receivable, year five, Gross charge-offs			(1,077)		(1,136)
Financing receivable, prior to year five, Gross charge-offs, net			(1,080)		291
Revolving			(149)		(174)
Revolving-term			0		(50)
Total	$ (1,562)	$ (635)	(2,793)	$ (1,574)
Total					(1,381)
Commercial loans | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, year one, Gross charge-offs			0		0
Financing receivable, year two, Gross charge-offs			0		0
Financing receivable, year three, Gross charge-offs			0		(184)
Financing receivable, year four, Gross charge-offs			(458)		0
Financing receivable, year five, Gross charge-offs			(1,077)		(1,136)
Financing receivable, prior to year five, Gross charge-offs, net			(1,080)		295
Revolving			(39)		13
Revolving-term			0		(50)
Total	(1,534)	(543)	(2,654)	(1,342)
Total					(1,062)
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	(28)	(92)	(139)	(232)
Consumer loans | Single family
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0	0	0
Consumer loans | Home equity and other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, year one, Gross charge-offs			0		0
Financing receivable, year two, Gross charge-offs			(24)		(106)
Financing receivable, year three, Gross charge-offs			(5)		(22)
Financing receivable, year four, Gross charge-offs			0		0
Financing receivable, year five, Gross charge-offs			0		0
Financing receivable, prior to year five, Gross charge-offs, net			0		(4)
Revolving			(110)		(187)
Revolving-term			0		0
Total	$ (28)	$ (92)	$ (139)	$ (232)	$ (319)