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Note 3 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, before Allowance for Credit Loss	$ 4,600,781	$ 4,303,758
Financing Receivable, Nonaccrual, Interest Income	300	200	$ 100
Financing Receivable, Revolving, Converted to Term Loan During Period	9,100	6,400
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,300
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) From Forecast Changes	(2,200)	(2,000)
Financing Receivable, Individually Evaluated for Credit Loss	7,400	5,400
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,200	400
Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 3,707,304	$ 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	$ 19,100	$ 17,800
Retail Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	893,477	888,459
Retail Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, before Allowance for Credit Loss	52,000	38,100
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Financing Receivable, before Allowance for Credit Loss	$ 827,597	$ 837,406
Financing Receivables, Prepayment Speed Assumed	7.80%	9.00%

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Amount of interest income on financing receivable on nonaccrual status.

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