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Note 7 - Investment Securities (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss	$ 2,800		$ 2,800		$ 4,600
Equity Securities, FV-NI, Unrealized Gain (Loss)	3,300	$ 4,300	(2,318)	$ (6,204)
Equity Securities, FV-NI, Decrease in Unrealized Loss			3,900
Equity Securities, FV-NI, Current	$ 32,111		$ 32,111		$ 34,429
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	169		169		182
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0		$ 0
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	0		0
Debt Securities, Available-for-Sale, Excluding Accrued Interest	1,643,450		1,643,450		$ 1,547,128
Asset Pledged as Collateral [Member] | Public Deposits and Other Borrowings [Member]
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 19,500		$ 19,500		$ 17,800
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	141		141
Corporate Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	12		12		16
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 165,875		$ 165,875		$ 207,945
US Government Corporations and Agencies Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	11		11		9
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 6,860		$ 6,860		$ 9,149
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	3		3		3
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 23,302		$ 23,302		$ 24,556
US Treasury Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	2		2
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 776,833		$ 776,833		$ 621,462
Collateralized Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions					154
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 645,575		$ 645,575		$ 684,016

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