Note 7 - Fair Value Measurement - Fair Value Quantitative Information (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Discounted Appraised Value [Member]
Other real estate owned	$ 1,922	$ 2,254
Discounted Appraised Value [Member] | Minimum [Member] | Measurement Input, Cost to Sell [Member]
Fair value measurements, range	0.06	0.06
Discounted Appraised Value [Member] | Minimum [Member] | Measurement Input, Discount for Lack of Marketability [Member]
Fair value measurements, range	0	0
Discounted Appraised Value [Member] | Maximum [Member] | Measurement Input, Cost to Sell [Member]
Fair value measurements, range	0.1	0.1
Discounted Appraised Value [Member] | Maximum [Member] | Measurement Input, Discount for Lack of Marketability [Member]
Fair value measurements, range	0.1	0.43
Discounted Appraised Value [Member] | Weighted Average [Member] | Measurement Input, Cost to Sell [Member]
Fair value measurements, range	0.08	0.08
Discounted Appraised Value [Member] | Weighted Average [Member] | Measurement Input, Discount for Lack of Marketability [Member]
Fair value measurements, range	0	0.07
Internal Evaluations [Member]
Other real estate owned	$ 577	$ 995
Internal Evaluations [Member] | Minimum [Member]
Fair value measurements, range	0.29	0.19
Internal Evaluations [Member] | Maximum [Member]
Fair value measurements, range	0.29	0.19
Internal Evaluations [Member] | Weighted Average [Member]
Fair value measurements, range	0.29	0.19