Note 3 - Available-for-sale Securities - Investment Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale securities in continuous loss position, less than 12 months, fair value	$ 19,915	$ 9,208
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss	(421)	(148)
Available-for-sale securities in continuous loss position, 12 months or more, fair value	17,935	19,628
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss	(1,002)	(1,041)
Available-for-sale securities in continuous loss position, fair value	37,850	28,836
Available-for-sale securities in continuous loss position, unrealized loss	(1,423)	(1,189)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities in continuous loss position, less than 12 months, fair value	14,055	5,797
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss	(288)	(14)
Available-for-sale securities in continuous loss position, 12 months or more, fair value	77	1,476
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss	(1)	(3)
Available-for-sale securities in continuous loss position, fair value	14,132	7,273
Available-for-sale securities in continuous loss position, unrealized loss	(289)	(17)
Corporate Debt Securities [Member]
Available-for-sale securities in continuous loss position, less than 12 months, fair value
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss
Available-for-sale securities in continuous loss position, 12 months or more, fair value	13,047	13,015
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss	(952)	(984)
Available-for-sale securities in continuous loss position, fair value	13,047	13,015
Available-for-sale securities in continuous loss position, unrealized loss	(952)	(984)
Subordinated Notes [Member]
Available-for-sale securities in continuous loss position, less than 12 months, fair value	999	1,878
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss	(1)	(122)
Available-for-sale securities in continuous loss position, 12 months or more, fair value	1,104	1,103
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss	(5)	(6)
Available-for-sale securities in continuous loss position, fair value	2,103	2,981
Available-for-sale securities in continuous loss position, unrealized loss	(6)	(128)
SBA Loan Pools [Member]
Available-for-sale securities in continuous loss position, less than 12 months, fair value	4,458	1,533
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss	(127)	(12)
Available-for-sale securities in continuous loss position, 12 months or more, fair value	3,707	4,034
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss	(44)	(48)
Available-for-sale securities in continuous loss position, fair value	8,165	5,567
Available-for-sale securities in continuous loss position, unrealized loss	(171)	$ (60)
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities in continuous loss position, less than 12 months, fair value	403
Available-for-sale securities in continuous loss position, less than 12 months, unrealized loss	(5)
Available-for-sale securities in continuous loss position, 12 months or more, fair value
Available-for-sale securities in continuous loss position, 12 months or more, unrealized loss
Available-for-sale securities in continuous loss position, fair value	403
Available-for-sale securities in continuous loss position, unrealized loss	$ (5)