Note 9 - Disclosures About Fair Value of Assets and Liabilities - Fair Value Quantitative Information (Details) - Fair Value, Inputs, Level 3 [Member] - Market Approach Valuation Technique [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Impaired Loans [Member]
Assets, fair value	$ 1,474	$ 1,006
Valuation technique	Market Comparable	Market Comparable
Unobservable input	Discount to reflect realizable value	Discount to reflect realizable value
Impaired Loans [Member] | Minimum [Member]
Range	0.00%	0.00%
Impaired Loans [Member] | Maximum [Member]
Range	100.00%	100.00%
Impaired Loans [Member] | Weighted Average [Member]
Range	15.00%	7.00%
Foreclosed Assets Held For Sale [Member]
Assets, fair value		$ 149
Valuation technique	Market Comparable	Market Comparable
Unobservable input	Discount to reflect realizable value	Discount to reflect realizable value
Range	0.00%	10.00%