Note 11 - Federal Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Allowance for loan losses	$ 5,017,000	$ 4,700,000
Deferred compensation	577,000	630,000
Stock compensation	720,000	660,000
Nonaccrual loan interest income	239,000	297,000
Deferred loan fees	104,000	185,000
Deferred Tax Assets, Capital Loss Carryforwards	94,000	94,000
Fair value write-downs on foreclosed properties	26,000	15,000
Unrealized loss on securities	0	2,190,000
Other	683,000	340,000
Deferred tax asset before valuation allowance	7,460,000	9,111,000
Valuation allowance	(94,000)	(94,000)
Deferred tax asset after valuation allowance	7,366,000	9,017,000
Depreciation	1,743,000	1,205,000
Prepaid expenses	269,000	238,000
Core deposit intangible	787,000	1,142,000
Mortgage loan servicing rights	977,000	932,000
Unrealized gain on securities	982,000	0
Business combination adjustments	2,058,000	2,054,000
Other	485,000	183,000
Deferred tax liability	7,301,000	5,754,000
Total net deferred tax asset	$ 65,000	$ 3,263,000