Note 9 - Fair Value of Financial Instruments - Quantitative Information About Non-recurring Level 3 Fair Value of Financial Instruments and the Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value	$ 20,159	$ 15,501
Fair Value	20,159	15,501
Impaired Loans [Member]
Fair Value	20,159	14,968
Fair Value	20,159	14,968
Impaired Loans [Member] | Income Approach Valuation Technique [Member]
Fair Value	$ 1,566	$ 2,007
Range, loss severity discount	15.00%	15.00%
Fair Value	$ 1,566	$ 2,007
Impaired Loans [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Range, capitalization rate	6.50%	6.00%
Impaired Loans [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Range, capitalization rate	7.50%	7.50%
Impaired Loans [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Range, capitalization rate	7.00%	7.00%
Range, loss severity discount	15.00%	15.00%
Impaired Loans [Member] | Sales Approach Valuation Technique [Member]
Fair Value	$ 13,852	$ 8,703
Fair Value	$ 13,852	$ 8,703
Impaired Loans [Member] | Sales Approach Valuation Technique [Member] | Minimum [Member]
Range, loss severity discount	0.00%	0.00%
Range, comparability adjustments	50.00%	(40.00%)
Impaired Loans [Member] | Sales Approach Valuation Technique [Member] | Maximum [Member]
Range, loss severity discount	15.00%	15.00%
Range, comparability adjustments	16.20%	16.20%
Impaired Loans [Member] | Sales Approach Valuation Technique [Member] | Weighted Average [Member]
Range, loss severity discount	3.70%	7.70%
Range, comparability adjustments	0.60%	(1.50%)
Impaired Loans [Member] | Blended Income and Sales Approach [Member]
Fair Value	$ 4,741	$ 4,258
Range, loss severity discount		15.00%
Fair Value	$ 4,741	$ 4,258
Impaired Loans [Member] | Blended Income and Sales Approach [Member] | Minimum [Member]
Range, capitalization rate	5.00%	5.30%
Range, loss severity discount	14.50%
Range, comparability adjustments	(30.00%)	(50.00%)
Impaired Loans [Member] | Blended Income and Sales Approach [Member] | Maximum [Member]
Range, capitalization rate	9.80%	9.50%
Range, loss severity discount	15.00%
Range, comparability adjustments	25.00%	25.00%
Impaired Loans [Member] | Blended Income and Sales Approach [Member] | Weighted Average [Member]
Range, capitalization rate	7.50%	7.20%
Range, loss severity discount	15.00%	15.00%
Range, comparability adjustments	0.80%	(0.60%)
Other Real Estate Owned [Member]
Fair Value		$ 533
Fair Value		533
Other Real Estate Owned [Member] | Blended Income and Sales Approach [Member]
Fair Value		533
Fair Value		$ 533
Other Real Estate Owned [Member] | Blended Income and Sales Approach [Member] | Minimum [Member]
Range, comparability adjustments		3.30%
Other Real Estate Owned [Member] | Blended Income and Sales Approach [Member] | Maximum [Member]
Range, comparability adjustments		18.60%
Other Real Estate Owned [Member] | Blended Income and Sales Approach [Member] | Weighted Average [Member]
Range, comparability adjustments		11.00%