Note 7 - Fair Value Measurements - Impaired Loans and Other Real Estate Owned Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Impaired loans net of valuation allowance	$ 1,248	$ 1,303
Other real estate owned net of valuation allowance	2,214	2,817
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	1,248	1,303
Other real estate owned net of valuation allowance	$ 2,214	$ 2,817