Note 6 - Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Beginning Balance	$ 384,754	$ 394,169
Other comprehensive income (loss)	1,789	(32,528)
Balance at end of period	413,708	378,065
AOCI Attributable to Parent [Member]
Beginning Balance	(36,515)	5,312
Other comprehensive income (loss) before reclassification	2,300	(41,276)
Federal income tax expense (benefit)	(483)	8,668
Other comprehensive income (loss) before reclassification, net of tax	1,817	(32,608)
Amounts reclassified from AOCI	(36)	101
Federal income tax expense (benefit)	8	(21)
Amounts reclassified from AOCI, net of tax	(28)	80
Other comprehensive income (loss)	1,789	(32,528)
Balance at end of period	$ (34,726)	$ (27,216)