Note 5 - Loans and the Allowance for Loan Losses (Details Textual) xbrli-pure in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Impaired Financing Receivable, Recorded Investment, Total	$ 2,244,000	$ 1,275,000	$ 2,270,000
Impaired Financing Receivable, Related Allowance	154,000	181,000	82,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	539,000	424,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,705,000	851,000
Impaired Financing Receivable, Average Recorded Investment, Total	1,777,000	1,160,000	1,760,000
Impaired Financing Receivable, Interest Income, Accrual Method, Total	62,000	71,000	73,000
Financing Receivable, Troubled Debt Restructuring	1,016,000	1,080,000
Financing Receivable Modifications Related Allowances	33,000	53,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	$ 0	$ 0
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Nonaccrual	$ 2,050,000	$ 1,117,000
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$ 158,000	$ 46,000	50,000
Number of Loans, 90 Days Past Due and Still Accruing	0	0
Impaired Financing Receivable, Interest Income, Cash Basis Method, Total	$ 0	$ 0	0
Deferred Loan Origination Costs	$ 2,294,000	$ 2,520,000	$ 1,789,000