Note 6 - Accumulated Other Comprehensive Income - Significant Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Investment securities gains on sale, net	[1]			$ 488
Income taxes			[1]	(166)
Net of tax			[1]	$ 322

[1] For unrealized gains on available-for-sale securities, amounts in parentheses indicate expenses and other amounts indicate income.