Note 4 - Loans (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Loan Balance For Reviewing High Risk Loans Minimum	$ 250,000		$ 250,000		$ 250,000
Impaired Financing Receivable, Recorded Investment, Total	24,179,000	$ 21,789,000	24,179,000	$ 21,789,000	24,473,000
Impaired Financing Receivable, Related Allowance	1,566,000	$ 1,474,000	1,566,000	$ 1,474,000	1,418,000
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	0	0	0	1
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down			$ 131,000
Financial Asset Acquired with Credit Deterioration [Member]
Impaired Financing Receivable, Recorded Investment, Total	$ 165,000	$ 0	165,000	$ 0	0
Impaired Financing Receivable, Related Allowance		$ 0		$ 0	$ 0