Note 10 - Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tax provision computed at federal statutory rate									$ 1,353	$ (1,018)	$ 2,143
State income tax, net of federal benefit									360	(260)	(340)
Tax exempt interest									(461)	(425)	(430)
Deferred tax only items									0	0	199
Other									138	353	6
Total provision (benefit) for income taxes	$ 1,548	$ (503)	$ 675	$ (330)	$ (1,031)	$ (516)	$ 105	$ 92	$ 1,390	$ (1,350)	$ 1,578