Note 4 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Securities available-for-sale, amortized costs	$ 477,878	$ 435,166
Securities available-for-sale, gross unrealized gains	12,900	2,951
Securities available-for-sale, fair values	489,926	435,263
Securities available-for-sale, gross unrealized losses	852	2,854
US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized costs	68,909	119,903
Securities available-for-sale, gross unrealized gains	4,617	1,995
Securities available-for-sale, fair values	73,526	121,123
Securities available-for-sale, gross unrealized losses		775
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized costs	146,928	88,092
Securities available-for-sale, gross unrealized gains	4,535	791
Securities available-for-sale, fair values	150,880	88,239
Securities available-for-sale, gross unrealized losses	583	644
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, amortized costs	259,040	223,173
Securities available-for-sale, gross unrealized gains	3,461	45
Securities available-for-sale, fair values	262,232	221,783
Securities available-for-sale, gross unrealized losses	269	1,435
Corporate Debt Securities [Member]
Securities available-for-sale, amortized costs	3,001	3,998
Securities available-for-sale, gross unrealized gains	287	120
Securities available-for-sale, fair values	$ 3,288	$ 4,118

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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