Note 4 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Temporarily impaired securities, less than 12 months, fair value	$ 927	$ 2,500
Temporarily impaired securities, less than 12 months unrealized loss	78	27
Temporarily impaired securities, 12 months or more fair value	598,970	615,242
Temporarily impaired securities, 12 months or more unrealized loss	63,176	79,158
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	0
Temporarily impaired securities, less than 12 months unrealized loss	0	0
Temporarily impaired securities, 12 months or more fair value	320,432	311,844
Temporarily impaired securities, 12 months or more unrealized loss	32,645	42,060
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	924	884
Temporarily impaired securities, less than 12 months unrealized loss	78	1
Temporarily impaired securities, 12 months or more fair value	151,803	148,763
Temporarily impaired securities, 12 months or more unrealized loss	25,464	29,613
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	3	1,616
Temporarily impaired securities, less than 12 months unrealized loss	0	26
Temporarily impaired securities, 12 months or more fair value	119,869	147,922
Temporarily impaired securities, 12 months or more unrealized loss	4,427	6,698
Corporate Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	0
Temporarily impaired securities, less than 12 months unrealized loss	0	0
Temporarily impaired securities, 12 months or more fair value	5,876	5,750
Temporarily impaired securities, 12 months or more unrealized loss	631	754
US Treasury Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	0
Temporarily impaired securities, less than 12 months unrealized loss	0	0
Temporarily impaired securities, 12 months or more fair value	990	963
Temporarily impaired securities, 12 months or more unrealized loss	$ 9	$ 33

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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