INVESTMENT SECURITIES - Amortized cost and fair value of securities held-to-maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Investment securities held-to-maturity:
Amortized Cost	$ 75,610		$ 81,056
Gross Unrecognized Gains	10		13
Gross Unrecognized Losses	(9,133)		(6,351)
Fair Value	66,487		74,718
Allowance for credit losses: held-to-maturity securities	(71)		0
U.S. Treasury debt
Investment securities held-to-maturity:
Amortized Cost	250		243
Gross Unrecognized Gains	0		0
Gross Unrecognized Losses	(11)		(9)
Fair Value	239		234
Allowance for credit losses: held-to-maturity securities	0
Corporate bonds
Investment securities held-to-maturity:
Amortized Cost	23,729		23,819
Gross Unrecognized Gains	0		0
Gross Unrecognized Losses	(3,334)		(2,453)
Fair Value	20,395		21,366
Allowance for credit losses: held-to-maturity securities	(71)	$ (71)	0
GNMA mortgage-backed securities – residential
Investment securities held-to-maturity:
Amortized Cost	35,503		39,426
Gross Unrecognized Gains	0		0
Gross Unrecognized Losses	(4,152)		(2,800)
Fair Value	31,351		36,626
Allowance for credit losses: held-to-maturity securities	0
FNMA mortgage-backed securities – residential
Investment securities held-to-maturity:
Amortized Cost	6,178		6,708
Gross Unrecognized Gains	0		0
Gross Unrecognized Losses	(730)		(506)
Fair Value	5,448		6,202
Allowance for credit losses: held-to-maturity securities	0
Government CMO and MBS - commercial
Investment securities held-to-maturity:
Amortized Cost	6,033		6,786
Gross Unrecognized Gains	10		13
Gross Unrecognized Losses	(558)		(403)
Fair Value	5,485		6,396
Allowance for credit losses: held-to-maturity securities	0
Corporate CMO and MBS
Investment securities held-to-maturity:
Amortized Cost	3,917		4,074
Gross Unrecognized Gains	0		0
Gross Unrecognized Losses	(348)		(180)
Fair Value	3,569		3,894
Allowance for credit losses: held-to-maturity securities	$ 0	$ 0	$ 0