Note 3 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Financing Receivable, before Allowance for Credit Loss	$ 4,438,245		$ 4,303,758
Increase (Decrease) in Finance Receivables	$ 134,000
Loans and Leases Receivable, Percentage Period Increase (Decrease)	3.10%
Financing Receivable, Nonaccrual, Interest Income	$ 400	$ 100
Financing Receivable, Revolving, Converted to Term Loan During Period	5,000		6,400
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) From Forecast Changes	(2,300)		(2,000)
Financing Receivable, Individually Evaluated for Credit Loss	10,900		5,400
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	6,300		400
Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 3,533,279		$ 3,415,299
Financing Receivables, Prepayment Speed Assumed	2.00%		2.00%
Commercial Portfolio Segment [Member] \| Commercial and Industrial, Credit Cards to Business Customers [Member]
Financing Receivable, before Allowance for Credit Loss			$ 17,800
Retail Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 904,966		888,459
Retail Portfolio Segment [Member] \| Home Equity Loan [Member]
Financing Receivable, before Allowance for Credit Loss			38,100
Retail Portfolio Segment [Member] \| One to Four Family Mortgages [Member]
Financing Receivable, before Allowance for Credit Loss	$ 849,625		$ 837,406
Financing Receivables, Prepayment Speed Assumed	9.00%		9.00%
Retail Portfolio Segment [Member] \| Other Consumer Loans [Member]
Financing Receivable, before Allowance for Credit Loss	$ 55,341		$ 51,053
Financing Receivables, Prepayment Speed Assumed	9.00%		9.00%

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.

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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.

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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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Amount of interest income on financing receivable on nonaccrual status.

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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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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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