FAIR VALUES OF FINANCIAL INSTRUMENTS - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Cash and due from banks	$ 125,818	$ 122,594
Interest-bearing deposits	352,695	126,061
Investment securities available for sale	1,794,208	1,976,661
Investment securities held to maturity	1,934,601	1,907,865
Loans held for sale	9,408	9,094
Loans, net	11,573,561	11,156,217
Federal Home Loan Bank stock	41,878	38,525
Derivative assets	74,345	93,036
Interest receivable	85,515	85,070
Liabilities:
Deposits	14,681,780	14,356,953
Borrowings:
Federal funds purchased	20	171,560
Securities sold under repurchase agreements	179,051	167,396
Federal Home Loan Bank advances	819,690	615,211
Subordinated debentures and other borrowings	121,402	122,102
Derivative liabilities	73,914	92,770
Interest payable	11,979	7,530
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and due from banks	125,818	122,594
Interest-bearing deposits	352,695	126,061
Investment securities available for sale	2,082	2,459
Investment securities held to maturity	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	12,921,842	13,105,936
Borrowings:
Federal funds purchased	0	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	1,788,664	1,970,763
Investment securities held to maturity	1,920,038	1,893,271
Loans held for sale	9,408	9,094
Loans, net	0	0
Federal Home Loan Bank stock	41,878	38,525
Derivative assets	74,345	93,036
Interest receivable	85,515	85,070
Liabilities:
Deposits	1,759,938	1,251,017
Borrowings:
Federal funds purchased	20	171,560
Securities sold under repurchase agreements	179,051	167,396
Federal Home Loan Bank advances	819,690	615,211
Subordinated debentures and other borrowings	121,402	122,102
Derivative liabilities	73,914	92,770
Interest payable	11,979	7,530
Significant Unobservable Inputs (Level 3)
Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	3,462	3,439
Investment securities held to maturity	14,563	14,594
Loans held for sale	0	0
Loans, net	11,573,561	11,156,217
Federal Home Loan Bank stock	0	0
Derivative assets	0	0
Interest receivable	0	0
Liabilities:
Deposits	0	0
Borrowings:
Federal funds purchased	0	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	125,818	122,594
Interest-bearing deposits	352,695	126,061
Investment securities available for sale	1,794,208	1,976,661
Investment securities held to maturity	2,263,181	2,287,127
Loans held for sale	9,408	9,094
Loans, net	12,018,409	11,780,617
Federal Home Loan Bank stock	41,878	38,525
Derivative assets	74,345	93,036
Interest receivable	85,515	85,070
Liabilities:
Deposits	14,703,287	14,382,745
Borrowings:
Federal funds purchased	20	171,560
Securities sold under repurchase agreements	179,067	167,413
Federal Home Loan Bank advances	823,577	823,674
Subordinated debentures and other borrowings	151,312	151,298
Derivative liabilities	73,914	92,770
Interest payable	$ 11,979	$ 7,530

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