Note 16 - Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss) and Other Related Tax Effects (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in net unrealized losses arising during the year, before tax	$ 93,326	$ (434,107)	$ (91,891)
Changes in net unrealized losses arising during the year, tax	(27,591)	128,338	27,167
Changes in net unrealized losses arising during the year, net of tax	65,735	(305,769)	(64,724)
Reclassification of losses (gains) included in net income	125	0	(34)
Deferred tax (benefit on losses) expense on gains included in net income	(37)	0	10
Reclassification of losses included in net income, net of tax	88		(24)
Other comprehensive income (loss), before tax	93,451	(434,107)	(91,925)
Other comprehensive income, tax	(27,628)	128,338	27,177
Other comprehensive income (loss), net of tax	65,823	(305,769)	(64,748)
Reclassification of gains (losses) included in net income, before tax	125	0	(34)
Reclassification of gains (losses) included in net income, tax	$ (37)	$ 0	$ 10