Note 3 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Temporarily impaired securities, less than 12 months, fair value	$ 2,500	$ 389,208
Temporarily impaired securities, less than 12 months unrealized loss	27	39,109
Temporarily impaired securities, 12 months or more fair value	615,242	259,070
Temporarily impaired securities, 12 months or more unrealized loss	79,158	64,043
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	144,574
Temporarily impaired securities, less than 12 months unrealized loss	0	12,699
Temporarily impaired securities, 12 months or more fair value	311,844	190,950
Temporarily impaired securities, 12 months or more unrealized loss	42,060	42,303
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	884	94,657
Temporarily impaired securities, less than 12 months unrealized loss	1	18,373
Temporarily impaired securities, 12 months or more fair value	148,763	52,134
Temporarily impaired securities, 12 months or more unrealized loss	29,613	19,645
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	1,616	144,198
Temporarily impaired securities, less than 12 months unrealized loss	26	7,326
Temporarily impaired securities, 12 months or more fair value	147,922	15,165
Temporarily impaired securities, 12 months or more unrealized loss	6,698	1,913
Corporate Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	4,843
Temporarily impaired securities, less than 12 months unrealized loss	0	655
Temporarily impaired securities, 12 months or more fair value	5,750	821
Temporarily impaired securities, 12 months or more unrealized loss	754	182
US Treasury Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	0	936
Temporarily impaired securities, less than 12 months unrealized loss	0	56
Temporarily impaired securities, 12 months or more fair value	963	0
Temporarily impaired securities, 12 months or more unrealized loss	$ 33	$ 0

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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