Note 9 - Accumulated Other Comprehensive Income (Loss) - Significant Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Provision for income taxes	$ 384			$ 444			$ 892	$ 1,372
Total reclassifications for the period	1,798	$ 1,294	$ 1,190	2,168	$ 2,140	$ 2,082	4,282	6,391
Reclassification out of Accumulated Other Comprehensive Income [Member]
Provision for income taxes				9			133	9
Total reclassifications for the period				(33)			(502)	(34)
Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Unrealized gains and losses on available-for-sale securities				$ (42)			$ (635)	$ (43)