FAIR VALUE - Carrying amounts and estimated fair values of other financial instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Financial assets:
Held-to-maturity securities, fair value	$ 1,372,481	$ 1,370,464
Carrying Value
Financial assets:
Net loans	11,191,128	10,861,836
Held-to-maturity securities, fair value	1,478,386	1,454,166
Other investment securities	5,194	0
Financial liabilities:
Deposits	14,710,409	14,387,085
Securities sold under agreement to repurchase, short-term	157,577	231,163
Other Federal Home Loan Bank borrowings	425,576	450,439
Fair Value
Financial assets:
Net loans	10,995,577	10,745,154
Held-to-maturity securities, fair value	1,372,481	1,370,464
Other investment securities	5,194	0
Financial liabilities:
Deposits	14,699,447	14,377,084
Securities sold under agreement to repurchase, short-term	157,577	231,163
Other Federal Home Loan Bank borrowings	$ 427,624	$ 456,821

Fair value portion of borrowing from Federal Home Loan Bank classified as other.

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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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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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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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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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