Note 3 - Securities - Available-for-sale Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale debt securities, amortized cost	$ 294,583	$ 268,971
Available-for-sale debt securities, gross unrealized holding gains	10,224	4,374
Available-for-sale debt securities, gross unrealized holding losses	2,169	506
Available-for-sale debt securities, at fair value	302,638	272,839
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale debt securities, amortized cost	143,279	115,428
Available-for-sale debt securities, gross unrealized holding gains	6,692	2,694
Available-for-sale debt securities, gross unrealized holding losses	173	359
Available-for-sale debt securities, at fair value	149,798	117,763
Residential Mortgage Backed Securities [Member]
Available-for-sale debt securities, amortized cost	77,777	79,606
Available-for-sale debt securities, gross unrealized holding gains	1,914	780
Available-for-sale debt securities, gross unrealized holding losses	480	92
Available-for-sale debt securities, at fair value	79,211	80,294
Commercial Mortgage Backed Securities [Member]
Available-for-sale debt securities, amortized cost	13,339	17,414
Available-for-sale debt securities, gross unrealized holding gains	699	320
Available-for-sale debt securities, gross unrealized holding losses	49	11
Available-for-sale debt securities, at fair value	13,989	17,723
Collateralized Mortgage Backed Securities [Member]
Available-for-sale debt securities, amortized cost	18,111	18,142
Available-for-sale debt securities, gross unrealized holding gains	682	343
Available-for-sale debt securities, gross unrealized holding losses
Available-for-sale debt securities, at fair value	18,793	18,485
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Available-for-sale debt securities, amortized cost	24,192	25,069
Available-for-sale debt securities, gross unrealized holding gains	187	49
Available-for-sale debt securities, gross unrealized holding losses	614	43
Available-for-sale debt securities, at fair value	23,765	25,075
Corporate Debt Securities [Member]
Available-for-sale debt securities, amortized cost	10,000	7,000
Available-for-sale debt securities, gross unrealized holding gains	48	182
Available-for-sale debt securities, gross unrealized holding losses	464
Available-for-sale debt securities, at fair value	9,584	7,182
Asset-backed Securities [Member]
Available-for-sale debt securities, amortized cost	7,191	5,618
Available-for-sale debt securities, gross unrealized holding gains		4
Available-for-sale debt securities, gross unrealized holding losses	389	1
Available-for-sale debt securities, at fair value	6,802	5,621
Negotiable Certificates of Deposit [Member]
Available-for-sale debt securities, amortized cost	694	694
Available-for-sale debt securities, gross unrealized holding gains	2	2
Available-for-sale debt securities, gross unrealized holding losses
Available-for-sale debt securities, at fair value	$ 696	$ 696

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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-SubTopic 10
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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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