Note 3 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities available-for-sale, amortized costs	$ 435,166	$ 431,428
Securities available-for-sale, gross unrealized gains	2,951	1,709
Securities available-for-sale, gross unrealized losses	2,854	8,127
Securities available-for-sale, fair values	435,263	425,010
US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized costs	119,903	306,264
Securities available-for-sale, gross unrealized gains	1,995	449
Securities available-for-sale, gross unrealized losses	775	6,666
Securities available-for-sale, fair values	121,123	300,047
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized costs	88,092	118,564
Securities available-for-sale, gross unrealized gains	791	1,218
Securities available-for-sale, gross unrealized losses	644	1,166
Securities available-for-sale, fair values	88,239	118,616
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, amortized costs	223,173	586
Securities available-for-sale, gross unrealized gains	45	42
Securities available-for-sale, gross unrealized losses	1,435	0
Securities available-for-sale, fair values	221,783	628
Corporate Debt Securities [Member]
Securities available-for-sale, amortized costs	3,998	6,014
Securities available-for-sale, gross unrealized gains	120
Securities available-for-sale, gross unrealized losses		295
Securities available-for-sale, fair values	$ 4,118	$ 5,719

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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