Note 8 - Borrowed Funds (Details Textual) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025
Advance from Federal Home Loan Bank	$ 200,000		$ 0
Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds	7,020,000		7,890,000
Debt Securities, Available-for-Sale, Excluding Accrued Interest	1,589,036		1,658,223
Payments for Repurchase of Trust Preferred Securities	54,125	$ (0)
Junior Subordinated Debt [Member]
Gain (Loss) on Extinguishment of Debt	0
Junior Subordinated Notes, Noncurrent	$ 65,000		$ 119,100
Debt Instrument, Interest Rate, Effective Percentage	6.21%		6.76%
Debt Instrument, Term (Year)	30 years
Asset Not Pledged as Collateral [Member] \| Federal Home Loan Bank Securities [Member]
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 1,570,000		$ 1,640,000
Over-night Borrowings [Member]
Advance from Federal Home Loan Bank	200,000		0
Non Overnight Borrowings [Member]
Advance from Federal Home Loan Bank	$ 200,000		$ 0
Federal Home Loan Bank, Advance, Branch of FHLBank, Interest Rate	4.42%

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Period between issuance and maturity of debt instrument, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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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Rate of interest applicable on advance from Federal Home Loan Bank (FHLBank).

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments, excluding current portion.

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