Note 3 - Loans and Allowance for Loan Losses - Allowance Related to Troubled Debt Restructurings (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Related allowance	$ 696,000	$ 444,000
Commercial Portfolio Segment [Member]
Related allowance	460,000	248,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Related allowance	85,000	107,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Related allowance	0	0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Related allowance	375,000	141,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Related allowance	0	0
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Related allowance	0	0
Retail Portfolio Segment [Member]
Related allowance	236,000	196,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Related allowance	215,000	196,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Related allowance	$ 21,000	$ 0