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				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Provision for income taxes	$ 266		$ 473		$ 508	$ 929
Total reclassifications for the period	1,294	$ 1,190	2,140	$ 2,082	2,484	4,222
Reclassification out of Accumulated Other Comprehensive Income [Member]
Provision for income taxes	117				133
Total reclassifications for the period	(440)		1		(502)	(1)
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	$ (557)		$ 1		$ (635)	$ (1)