FAIR VALUE MEASURES - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financial assets:
Cash and due from banks	$ 249,676	$ 244,980
Interest-bearing deposits in banks	920,594	975,397
Debt securities held-to-maturity	159,144	144,028
Financial liabilities:
Other borrowings	376,700	291,788
Subordinated deferrable interest debentures	133,306	132,309
Carrying Amount
Financial assets:
Cash and due from banks	249,676	244,980
Interest-bearing deposits in banks	920,594	975,397
Debt securities held-to-maturity	176,487	164,677
Loans, net	20,667,440	20,356,125
Financial liabilities:
Deposits	21,932,675	21,722,448
Other borrowings	376,700	291,788
Subordinated deferrable interest debentures	133,306	132,309
Fair Value
Financial assets:
Cash and due from banks	249,676	244,980
Interest-bearing deposits in banks	920,594	975,397
Debt securities held-to-maturity	159,144	144,028
Loans, net	20,315,137	19,882,553
Financial liabilities:
Deposits	21,928,032	21,721,421
Other borrowings	379,646	291,213
Subordinated deferrable interest debentures	142,254	142,202
Fair Value \| Level 1
Financial assets:
Cash and due from banks	249,676	244,980
Interest-bearing deposits in banks	920,594	975,397
Debt securities held-to-maturity	0	0
Loans, net	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Subordinated deferrable interest debentures	0	0
Fair Value \| Level 2
Financial assets:
Cash and due from banks	0	0
Interest-bearing deposits in banks	0	0
Debt securities held-to-maturity	159,144	144,028
Loans, net	0	0
Financial liabilities:
Deposits	21,928,032	21,721,421
Other borrowings	379,646	291,213
Subordinated deferrable interest debentures	142,254	142,202
Fair Value \| Level 3
Financial assets:
Cash and due from banks	0	0
Interest-bearing deposits in banks	0	0
Debt securities held-to-maturity	0	0
Loans, net	20,315,137	19,882,553
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Subordinated deferrable interest debentures	$ 0	$ 0

For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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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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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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