Note 2 - Securities - Securities with Unrealized Losses Aggregated by Investment Category and Time with Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Less than 12 months, Fair Value	$ 269,072	$ 515,182
Less than 12 months, Unrealized Losses	49,027	10,599
More than 12 months, Fair Value	257,220	102,211
More than 12 months, Unrealized Losses	49,609	4,196
Total, Fair Value	526,292	617,393
Total, Unrealized Losses	98,636	14,795
US Treasury and Government [Member]
Less than 12 months, Fair Value	0	0
Less than 12 months, Unrealized Losses	0	0
More than 12 months, Fair Value	0	0
More than 12 months, Unrealized Losses	0	0
Total, Fair Value	0	0
Total, Unrealized Losses	0	0
US Treasury Securities [Member]
Less than 12 months, Fair Value	0	89,958
Less than 12 months, Unrealized Losses	0	1,311
More than 12 months, Fair Value	77,554	0
More than 12 months, Unrealized Losses	13,372	0
Total, Fair Value	77,554	89,958
Total, Unrealized Losses	13,372	1,311
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, Fair Value	181,857	130,001
Less than 12 months, Unrealized Losses	44,576	3,253
More than 12 months, Fair Value	40,756	15,237
More than 12 months, Unrealized Losses	12,735	856
Total, Fair Value	222,613	145,238
Total, Unrealized Losses	57,311	4,109
Collateralized Mortgage-Backed Securities [Member]
Less than 12 months, Fair Value	86,499	261,560
Less than 12 months, Unrealized Losses	4,410	5,709
More than 12 months, Fair Value	125,765	86,974
More than 12 months, Unrealized Losses	22,994	3,340
Total, Fair Value	212,264	348,534
Total, Unrealized Losses	27,404	9,049
Corporate Debt Securities [Member]
Less than 12 months, Fair Value	716	17,369
Less than 12 months, Unrealized Losses	41	233
More than 12 months, Fair Value	0	0
More than 12 months, Unrealized Losses	0	0
Total, Fair Value	716	17,369
Total, Unrealized Losses	41	233
Asset-Backed Securities [Member]
Less than 12 months, Fair Value	0	16,294
Less than 12 months, Unrealized Losses	0	93
More than 12 months, Fair Value	13,145	0
More than 12 months, Unrealized Losses	508	0
Total, Fair Value	13,145	16,294
Total, Unrealized Losses	$ 508	$ 93

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
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-Publisher FASB
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Amount of accumulated unrealized loss on 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 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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