SECURITIES - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Securities available-for-sale:
Transfer from securities held-to-maturity	$ 0	$ 0	$ 400,000,000.0
Securities available-for-sale transferred to held-to-maturity			372,153,000
Unrealized loss on transfer of securities to held to maturity			27,800,000
Transfers to or from securities held-to-maturity			0
Securities held-to-maturity	$ 520,069,000	$ 520,069,000		$ 505,759,000
Number of holdings of securities of any one issuer in an amount greater than 10% of stockholders equity	0	0		0
Threshold for disclosure percentage		10.00%		10.00%
Available for sale debt securities, unrealized loss position due to credit	$ 0	$ 0
Allowance for credit losses on available for sale debt securities	0	0
Accrued interest receivable on securities		5,300,000		$ 5,400,000
Gain (loss) on transfer of securities to held-to-maturity			0
Unrealized losses are related to credit losses	0	0
Securities pledged
Securities available-for-sale:
Carrying amount of securities pledged	$ 573,900,000	$ 573,900,000		$ 631,400,000
Financial Instrument, Owned, Pledged Status [Extensible Enumeration]	Securities pledged	Securities pledged		Securities pledged
Carrying Amount
Securities available-for-sale:
Securities held-to-maturity	$ 603,960,000	$ 603,960,000		$ 585,798,000
Fair Value
Securities available-for-sale:
Securities available-for-sale transferred to held-to-maturity			$ 372,200,000
Securities held-to-maturity	520,069,000	520,069,000		505,759,000
Agency collateralized mortgage obligations ("CMOs")
Securities available-for-sale:
Securities held-to-maturity	190,264,000	190,264,000		184,929,000
Agency Notes
Securities available-for-sale:
Securities held-to-maturity	76,075,000	76,075,000		75,062,000
Pass-through mortgage-backed securities ("MBS") issued by government sponsored entities ("GSEs")
Securities available-for-sale:
Securities held-to-maturity	246,070,000	246,070,000		237,321,000
Available for sale debt securities, unrealized loss position due to credit	$ 222,584,000	$ 222,584,000		$ 241,240,000