Note 11 - Federal Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Allowance for loan losses	$ 4,700,000	$ 4,095,000
Deferred compensation	630,000	673,000
Stock compensation	660,000	501,000
Nonaccrual loan interest income	297,000	425,000
Deferred loan fees	185,000	211,000
Deferred Tax Assets, Capital Loss Carryforwards	94,000	94,000
Fair value write-downs on foreclosed properties	15,000	23,000
Unrealized loss on securities	2,190,000	1,303,000
Other	340,000	311,000
Deferred tax asset before valuation allowance	9,111,000	7,636,000
Valuation allowance	(94,000)	(94,000)
Deferred tax asset after valuation allowance	9,017,000	7,542,000
Depreciation	1,205,000	727,000
Prepaid expenses	238,000	244,000
Core deposit intangible	1,142,000	1,565,000
Mortgage loan servicing rights	932,000	1,072,000
Business combination adjustments	2,054,000	1,784,000
Other	183,000	146,000
Deferred tax liability	5,754,000	5,538,000
Total net deferred tax asset	$ 3,263,000	$ 2,004,000