FAIR VALUES OF FINANCIAL INSTRUMENTS - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Assets:
Cash and due from banks	$ 105,372	$ 112,649
Interest-bearing deposits	168,528	436,080
Investment securities available for sale	1,618,893	1,627,112
Investment securities held to maturity, net	1,779,216	1,870,374
Loans held for sale	32,292	18,934
Loans, net	12,121,987	11,958,301
Federal Home Loan Bank stock	41,738	41,769
Derivative assets	87,777	79,379
Interest receivable	97,546	97,664
Liabilities:
Deposits	14,557,131	14,811,957
Borrowings:
Federal funds purchased	147,229
Securities sold under repurchase agreements	100,451	157,265
Federal Home Loan Bank advances	822,958	707,377
Subordinated debentures and other borrowings	84,091	149,995
Derivative liabilities	87,236	79,008
Interest payable	18,554	18,912
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and due from banks	105,372	112,649
Interest-bearing deposits	168,528	436,080
Investment securities available for sale	0	0
Investment securities held to maturity, net	0	0
Loans held for sale	0	0
Loans, net	0	0
Federal Home Loan Bank stock	0	0
Derivative assets	0	0
Interest receivable	0	0
Liabilities:
Deposits	12,096,840	12,482,295
Borrowings:
Federal funds purchased	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Derivative liabilities	0	0
Interest payable	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	1,615,669	1,623,802
Investment securities held to maturity, net	1,771,567	1,859,974
Loans held for sale	32,292	18,934
Loans, net	0	0
Federal Home Loan Bank stock	41,738	41,769
Derivative assets	87,777	79,379
Interest receivable	97,546	97,664
Liabilities:
Deposits	2,460,291	2,329,662
Borrowings:
Federal funds purchased	147,229
Securities sold under repurchase agreements	100,451	157,265
Federal Home Loan Bank advances	822,958	707,377
Subordinated debentures and other borrowings	84,091	149,995
Derivative liabilities	87,236	79,008
Interest payable	18,554	18,912
Significant Unobservable Inputs (Level 3)
Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	3,224	3,310
Investment securities held to maturity, net	7,649	10,400
Loans held for sale	0	0
Loans, net	12,121,987	11,958,301
Federal Home Loan Bank stock	0	0
Derivative assets	0	0
Interest receivable	0	0
Liabilities:
Deposits	0	0
Borrowings:
Federal funds purchased	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Derivative liabilities	0	0
Interest payable	0	0
Carrying Amount
Assets:
Cash and due from banks	105,372	112,649
Interest-bearing deposits	168,528	436,080
Investment securities available for sale	1,618,893	1,627,112
Investment securities held to maturity, net	2,134,195	2,184,252
Loans held for sale	32,292	18,934
Loans, net	12,450,113	12,281,093
Federal Home Loan Bank stock	41,738	41,769
Derivative assets	87,777	79,379
Interest receivable	97,546	97,664
Liabilities:
Deposits	14,569,070	14,821,453
Borrowings:
Federal funds purchased	147,229
Securities sold under repurchase agreements	100,451	157,280
Federal Home Loan Bank advances	832,703	712,852
Subordinated debentures and other borrowings	93,589	158,644
Derivative liabilities	87,236	79,008
Interest payable	$ 18,554	$ 18,912

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount excluding accrued interest, of 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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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Amount, before valuation allowance, of financing receivable classified as held-for-sale.

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Fair value portion of other liabilities.

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