Note 4 - Loans (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Loan Balance For Reviewing High Risk Loans Minimum	$ 250,000	$ 250,000	$ 250,000	$ 250,000	$ 250,000
Impaired Financing Receivable, Recorded Investment, Total	21,724,000	$ 23,535,000	21,724,000	$ 23,535,000	24,473,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	$ 0		$ 0
Financing Receivable, Modifications, Number of Contracts	0	0	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	1	0	1	1
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 859,000		$ 859,000	$ 131,000
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down			859,000	131,000
Impaired Financing Receivable, Related Allowance	1,639,000	$ 1,487,000	1,639,000	1,487,000	1,418,000
Financial Asset Acquired with Credit Deterioration [Member]
Impaired Financing Receivable, Recorded Investment, Total	155,000	0	155,000	0	0
Impaired Financing Receivable, Related Allowance	$ 8,000	$ 0	$ 8,000	$ 0	$ 0