SECURITIES - Amortized cost and Fair values of securities with gross unrealized gains and losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Available-for-sale:
Amortized Cost	$ 854,796	$ 934,456
Gross Unrealized Gains	12	106
Gross Unrealized Losses	(101,645)	(91,038)
Allowance for Credit Losses	0
Fair Value	753,163	843,524
Held-to-maturity
Amortized Cost	527,144	541,600
Gross Unrealized Gains	6	195
Gross Unrealized Losses	(76,837)	(62,994)
Fair Value	450,313	478,801
Allowance for Credit Losses	0
U.S. Treasury
Available-for-sale:
Amortized Cost	169,751	169,860
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(15,357)	(15,345)
Allowance for Credit Losses	0
Fair Value	154,394	154,515
U.S. government agency
Available-for-sale:
Amortized Cost	55,483	59,291
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4,768)	(4,134)
Allowance for Credit Losses	0
Fair Value	50,715	55,157
Held-to-maturity
Amortized Cost	88,442	88,424
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12,392)	(9,728)
Fair Value	76,050	78,696
Allowance for Credit Losses	0
Municipal
Available-for-sale:
Amortized Cost	231,444	275,972
Gross Unrealized Gains	1	46
Gross Unrealized Losses	(36,244)	(32,189)
Allowance for Credit Losses	0
Fair Value	195,201	243,829
Held-to-maturity
Amortized Cost	39,344	42,167
Gross Unrealized Gains	6	195
Gross Unrealized Losses	(1,686)	(314)
Fair Value	37,664	42,048
Allowance for Credit Losses	0
Agency residential
Available-for-sale:
Amortized Cost	197,549	213,676
Gross Unrealized Gains	9	5
Gross Unrealized Losses	(20,508)	(18,240)
Allowance for Credit Losses	0
Fair Value	177,050	195,441
Held-to-maturity
Amortized Cost	98,115	102,728
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(9,281)	(6,470)
Fair Value	88,834	96,258
Allowance for Credit Losses	0
Agency commercial
Available-for-sale:
Amortized Cost	142,920	150,060
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(18,593)	(17,172)
Allowance for Credit Losses	0
Fair Value	124,329	132,888
Held-to-maturity
Amortized Cost	301,243	308,281
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(53,478)	(46,482)
Fair Value	247,765	261,799
Allowance for Credit Losses	0
Corporate
Available-for-sale:
Amortized Cost	57,649	65,597
Gross Unrealized Gains	0	55
Gross Unrealized Losses	(6,175)	(3,958)
Allowance for Credit Losses	0
Fair Value	$ 51,474	$ 61,694

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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