Note 11 - Reconciliation of the Tax Provision (Details) - USD ($) $ 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
Reconciliation Of The Tax Provision [Abstract]
Provision at statutory rate									$ 3,193	$ 2,707	$ 4,825
Tax-exempt interest and dividend income									(538)	(577)	(948)
Bank-owned life insurance									(61)	(61)	(100)
Life insurance proceeds									0	0	(18)
Stock-based compensation expense									20	17	19
State income tax									205	(19)	82
Other									31	(95)	(14)
Net provision prior to discrete tax adjustments									2,850	1,972	3,846
DTL writeoff due to change in tax methods									0	(415)	0
Net DTA revaluation for change in tax rate under 2017 Tax Reform									0	0	2,054
Net provision	$ 623	$ 731	$ 679	$ 817	$ (339)	$ 767	$ 572	$ 557	$ 2,850	$ 1,557	$ 5,900
Provision at statutory rate									21.00%	21.00%	34.00%
Tax-exempt interest and dividend income									(3.50%)	(4.50%)	(6.70%)
Bank-owned life insurance									(0.40%)	(0.40%)	(0.70%)
Life insurance proceeds									(0.00%)	(0.00%)	(0.10%)
Stock-based compensation expense									0.10%	0.10%	0.10%
State income tax									1.30%	(0.10%)	0.60%
Other									0.20%	(0.80%)	(0.10%)
Net provision prior to discrete tax adjustments									18.70%	15.30%	27.10%
DTL writeoff for change in tax methods									0.00%	(3.20%)	0.00%
Net DTA revaluation for change in tax rate under 2017 Tax Reform									0.00%	0.00%	14.50%
Net provision									18.70%	12.10%	41.60%