Note 10 - Fair Values Measurement (Details Textual)	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 218,000		$ 453,000
Impaired Financing Receivable, Related Allowance	20,000		42,000
Impaired Loans [Member]
Impaired Financing Receivable, Related Allowance	20,000	$ 193,000	42,000
Impaired Financing Receivable Provision for Loan Losses	0	0
Measured for Impairment Using Fair Value of Collateral [Member] | Impaired Loans [Member]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 218,000	$ 873,000	$ 453,000
Measurement Input, Discount Rate [Member] | Minimum [Member]
Impaired Loans, Measurement Input	0.1
Measurement Input, Discount Rate [Member] | Maximum [Member]
Impaired Loans, Measurement Input	0.33
Measurement Input, Estimated Discount for Cost to Sell [Member] | Minimum [Member]
Impaired Loans, Measurement Input	0.06
Measurement Input, Estimated Discount for Cost to Sell [Member] | Maximum [Member]
Impaired Loans, Measurement Input	0.1
Routine Real Estate Collateral [Member] | Measurement Input, Discount Rate [Member]
Impaired Loans, Measurement Input	0.1
Thin Trading Market or Specialized Collateral [Member] | Measurement Input, Discount Rate [Member]
Impaired Loans, Measurement Input	0.25