Note 3 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, before Allowance for Credit Loss	$ 4,636,549		$ 4,600,781
Increase (Decrease) in Finance Receivables	$ 35,800
Loans and Leases Receivable, Percentage Period Increase (Decrease)	0.80%
Financing Receivable, Nonaccrual, Interest Income	$ 300	$ 200
Financing Receivable, Revolving, Converted to Term Loan During Period	300		9,100
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) From Forecast Changes	(100)		(2,200)
Financing Receivable, Individually Evaluated for Credit Loss	7,000		7,400
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 2,400		2,200
Financing Receivable, Modifications, Number of Contracts	0
Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 3,751,591		$ 3,707,304
Financing Receivables, Prepayment Speed Assumed	2.00%		2.00%
Retail Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 884,958		$ 893,477
Retail Portfolio Segment [Member] \| One to Four Family Mortgages [Member]
Financing Receivable, before Allowance for Credit Loss	$ 817,212		$ 827,597
Financing Receivables, Prepayment Speed Assumed	7.80%		7.80%
Retail Portfolio Segment [Member] \| Other Consumer Loans [Member]
Financing Receivable, before Allowance for Credit Loss	$ 67,746		$ 65,880
Financing Receivables, Prepayment Speed Assumed	7.80%		7.80%

Amount of increase (decrease) in allowance for credit loss on financing receivable due economic forecast changes.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

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Percentage of prepayment speed assumed under financing receivables.

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The percentage of increase or (decrease) during the period in loans and leases receivable during the period.

+ References

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Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss.

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

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Amount of interest income on financing receivable on nonaccrual status.

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- Definition

Amount of increase in term loan from conversion of revolving financing receivable.

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The increase (decrease) during the reporting period in outstanding loans including accrued interest.

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- Definition

Amortized cost, before allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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