Note 3 - Loans - Activity in Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Balance	$ 8,376	$ 8,880
Provision for loan losses	1,050
Loans charged off	(335)	(278)
Recoveries	59	84
Balance	9,150	8,686
Commercial Portfolio Segment [Member]
Balance	1,710	1,299
Provision for loan losses	339	143
Loans charged off	(29)
Recoveries	5	5
Balance	2,025	1,447
Commercial Real Estate Portfolio Segment [Member]
Balance	4,080	4,676
Provision for loan losses	141	(165)
Loans charged off	(29)	(15)
Recoveries	20	2
Balance	4,212	4,498
Residential Portfolio Segment [Member]
Balance	1,743	2,452
Provision for loan losses	220	(204)
Loans charged off	(75)	(82)
Recoveries	21	61
Balance	1,909	2,227
Consumer Portfolio Segment [Member]
Balance	485	130
Provision for loan losses	265	193
Loans charged off	(161)	(180)
Recoveries	4	16
Balance	593	159
Agriculture Portfolio Segment [Member]
Balance	355	321
Provision for loan losses	87	33
Loans charged off	(41)	(1)
Recoveries	8
Balance	409	353
Other Portfolio Segment [Member]
Balance	3	2
Provision for loan losses	(2)
Loans charged off
Recoveries	1
Balance	$ 2	$ 2