Note 3 - Investment Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	$ 8,407	$ 509
Securities held to maturity, less than 12 months, gross unrealized losses	(248)	(1)
Securities held to maturity, 12 months or more, fair value		10,047
Securities held to maturity, 12 months or more, gross unrealized losses		(142)
Securities held to maturity, fair value	8,407	10,556
Securities held to maturity, gross unrealized losses	(248)	(143)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	57,742	20,829
Securities available for sale, less than 12 months, gross unrealized losses	(485)	(110)
Securities available for sale, 12 months or more, fair value	9,945	20,703
Securities available for sale, 12 months or more, gross unrealized losses	(39)	(225)
Securities available for sale, fair value	67,687	41,532
Securities available for sale, gross unrealized losses	(524)	(335)
Municipal securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	10,110
Securities available for sale, less than 12 months, gross unrealized losses	(48)
Securities available for sale, 12 months or more, fair value	0	724
Securities available for sale, 12 months or more, gross unrealized losses	0	(4)
Securities available for sale, fair value	10,110	724
Securities available for sale, gross unrealized losses	(48)	(4)
U.S. govt. sponsored agency securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	3,199	1,431
Securities available for sale, less than 12 months, gross unrealized losses	(47)	(21)
Securities available for sale, 12 months or more, fair value		2,117
Securities available for sale, 12 months or more, gross unrealized losses		(56)
Securities available for sale, fair value	3,199	3,548
Securities available for sale, gross unrealized losses	(47)	(77)
Residential mortgage-backed and related securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	37,549	2,263
Securities available for sale, less than 12 months, gross unrealized losses	(338)	(17)
Securities available for sale, 12 months or more, fair value		17,862
Securities available for sale, 12 months or more, gross unrealized losses		(165)
Securities available for sale, fair value	37,549	20,125
Securities available for sale, gross unrealized losses	(338)	(182)
Asset-backed securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	6,884	16,886
Securities available for sale, less than 12 months, gross unrealized losses	(52)	(71)
Securities available for sale, 12 months or more, fair value	9,945
Securities available for sale, 12 months or more, gross unrealized losses	(39)
Securities available for sale, fair value	16,829	16,886
Securities available for sale, gross unrealized losses	$ (91)	(71)
Other Securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value		249
Securities available for sale, less than 12 months, gross unrealized losses		(1)
Securities available for sale, fair value		249
Securities available for sale, gross unrealized losses		$ (1)

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