Note 16 - Fair Value Measurements - Impaired Loans and Other Real Estate Owned Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Impaired loans net of valuation allowance	$ 1,303	$ 878
Other real estate owned net of valuation allowance	2,817	3,156
Fair Value, Inputs, Level 1 [Member]
Impaired loans net of valuation allowance	0	0
Other real estate owned net of valuation allowance	0	0
Fair Value, Inputs, Level 2 [Member]
Impaired loans net of valuation allowance	0	0
Other real estate owned net of valuation allowance	0	0
Fair Value, Inputs, Level 3 [Member]
Impaired loans net of valuation allowance	1,303	878
Other real estate owned net of valuation allowance	$ 2,817	$ 3,156