Note 7 - Fair Value Measurements - Impaired Loans and Other Real Estate Owned Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Impaired loans net of valuation allowance	$ 1,004	$ 1,005
Other real estate owned net of valuation allowance	1,584	1,612
Fair Value, Inputs, Level 1 [Member]
Impaired loans net of valuation allowance		0
Other real estate owned net of valuation allowance		0
Fair Value, Inputs, Level 2 [Member]
Impaired loans net of valuation allowance		0
Other real estate owned net of valuation allowance		0
Fair Value, Inputs, Level 3 [Member]
Impaired loans net of valuation allowance	1,004	1,005
Other real estate owned net of valuation allowance	$ 1,584	$ 1,612