Note 4 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Securities available-for-sale, amortized costs	$ 330,512	$ 431,428
Securities available-for-sale, gross unrealized gains	4,412	1,709
Securities available-for-sale, gross unrealized losses	774	8,127
Securities available-for-sale, fair values	334,150	425,010
US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized costs	162,855	306,264
Securities available-for-sale, gross unrealized gains	2,636	449
Securities available-for-sale, gross unrealized losses	428	6,666
Securities available-for-sale, fair values	165,063	300,047
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized costs	82,520	118,564
Securities available-for-sale, gross unrealized gains	1,550	1,218
Securities available-for-sale, gross unrealized losses	48	1,166
Securities available-for-sale, fair values	84,022	118,616
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, amortized costs	81,141	586
Securities available-for-sale, gross unrealized gains	91	42
Securities available-for-sale, gross unrealized losses	298	0
Securities available-for-sale, fair values	80,934	628
Corporate Debt Securities [Member]
Securities available-for-sale, amortized costs	3,996	6,014
Securities available-for-sale, gross unrealized gains	135
Securities available-for-sale, gross unrealized losses		295
Securities available-for-sale, fair values	$ 4,131	$ 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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