Note 21 - Unaudited Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unaudited Quarterly Results Of Operations [Abstract]
Interest income	$ 11,600		$ 11,817		$ 11,712		$ 11,289		$ 11,203		$ 10,926		$ 10,562		$ 10,509		$ 46,418	$ 43,200	$ 38,102
Interest expense	2,435		2,635		2,601		2,453		2,383		2,222		1,862		1,718		10,124	8,185	5,680
Net interest income	9,165		9,182		9,111		8,836		8,820		8,704		8,700		8,791		36,294	35,015	32,422
Provision for (credit to) loan losses	375		550		150		225		187		568		187		188		1,300	1,130	1,400
Non-interest income	2,210		2,144		1,654		2,309		144		2,227		1,454		1,067		8,317	4,892	6,887
Non-interest expense	7,632		6,955		6,793		6,724		6,789		6,385		6,533		6,178		28,104	25,885	23,720
Income before income taxes	3,368		3,821		3,822		4,196		1,988		3,978		3,434		3,492		15,207	12,892	14,189
Provision for income taxes	623		731		679		817		(339)		767		572		557		2,850	1,557	5,900
Net income	$ 2,745		$ 3,090		$ 3,143		$ 3,379		$ 2,327		$ 3,211		$ 2,862		$ 2,935		$ 12,357	$ 11,335	$ 8,289
Earnings Per Share - basic	$ 0.78	[1]	$ 0.88	[1]	$ 0.90	[1]	$ 0.97	[1]	$ 0.67	[1]	$ 0.93	[1]	$ 0.83	[1]	$ 0.85	[1]	$ 3.53	$ 3.27	$ 2.42
Earnings Per Share - diluted	$ 0.78	[1]	$ 0.88	[1]	$ 0.90	[1]	$ 0.97	[1]	$ 0.67	[1]	$ 0.92	[1]	$ 0.82	[1]	$ 0.85	[1]	$ 3.53	$ 3.25	$ 2.41

[1] Due to rounding, quarterly earnings per share may not sum to annual earnings per share