Note 15 - Fair Values Measurements and Disclosures - Quantitative Information About Assets Measured at Fair Value (Details) - USD ($)		12 Months Ended
	Sep. 19, 2007	Dec. 31, 2017	Dec. 31, 2016
Discount rate	4.50%
Fair Value, Inputs, Level 3 [Member]
Discount rate		10.00%	10.00%
Market Approach Valuation Technique [Member] | Foreclosed Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure, noncrecurring		$ 84,100	$ 35,500
Appraisal adjustments		(42.00%)
Market Approach Valuation Technique [Member] | Foreclosed Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]
Appraisal adjustments			(23.00%)
Market Approach Valuation Technique [Member] | Foreclosed Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]
Appraisal adjustments			(50.00%)
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure, noncrecurring		$ 415,567	$ 2,856,621
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum [Member]
Appraisal adjustments		(50.00%)	(14.50%)
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum [Member]
Appraisal adjustments		(61.50%)	(86.50%)
Income Approach Valuation Technique [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure, noncrecurring		$ 95,115	$ 168,777