Note 3 - Investment Securities - Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Temporarily impaired securities, fair value	$ 567,944	$ 374,015
Temporarily impaired securities, unrealized losses	(56,183)	(4,956)
Temporarily impaired securities, fair value, less than 12 months	500,833	338,632
Temporarily impaired securities, unrealized losses, less than 12 months	(46,014)	(3,795)
Temporarily impaired securities, fair value, 12 months or longer	67,111	35,383
Temporarily impaired securities, unrealized losses, 12 months or longer	(10,169)	(1,161)
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, fair value	52,432	28,974
Temporarily impaired securities, unrealized losses	(5,708)	(625)
Temporarily impaired securities, fair value, less than 12 months	52,432	28,974
Temporarily impaired securities, unrealized losses, less than 12 months	(5,708)	(625)
Temporarily impaired securities, fair value, 12 months or longer	0	0
Temporarily impaired securities, unrealized losses, 12 months or longer	0	0
Residential Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	379,001	246,396
Temporarily impaired securities, unrealized losses	(36,883)	(2,884)
Temporarily impaired securities, fair value, less than 12 months	325,284	214,701
Temporarily impaired securities, unrealized losses, less than 12 months	(28,304)	(2,111)
Temporarily impaired securities, fair value, 12 months or longer	53,717	31,695
Temporarily impaired securities, unrealized losses, 12 months or longer	(8,579)	(773)
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	22,858	8,370
Temporarily impaired securities, unrealized losses	(2,769)	(463)
Temporarily impaired securities, fair value, less than 12 months	19,209	4,682
Temporarily impaired securities, unrealized losses, less than 12 months	(1,731)	(75)
Temporarily impaired securities, fair value, 12 months or longer	3,649	3,688
Temporarily impaired securities, unrealized losses, 12 months or longer	(1,038)	(388)
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, fair value	109,547	89,473
Temporarily impaired securities, unrealized losses	(10,766)	(982)
Temporarily impaired securities, fair value, less than 12 months	99,802	89,473
Temporarily impaired securities, unrealized losses, less than 12 months	(10,214)	(982)
Temporarily impaired securities, fair value, 12 months or longer	9,745	0
Temporarily impaired securities, unrealized losses, 12 months or longer	(552)	0
Corporate Debt Securities [Member]
Temporarily impaired securities, fair value	1,989
Temporarily impaired securities, unrealized losses	(9)
Temporarily impaired securities, fair value, less than 12 months	1,989
Temporarily impaired securities, unrealized losses, less than 12 months	(9)
Temporarily impaired securities, fair value, 12 months or longer	0
Temporarily impaired securities, unrealized losses, 12 months or longer	0
Asset-Backed Securities [Member]
Temporarily impaired securities, fair value	2,117	802
Temporarily impaired securities, unrealized losses	(48)	(2)
Temporarily impaired securities, fair value, less than 12 months	2,117	802
Temporarily impaired securities, unrealized losses, less than 12 months	(48)	(2)
Temporarily impaired securities, fair value, 12 months or longer	0	0
Temporarily impaired securities, unrealized losses, 12 months or longer	$ 0	$ 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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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