Note 21 - Earnings Per Share - Calculation of Diluted Weighted-average Shares Outstanding (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Basic:
Net income	$ 360,591	$ 5,295,127
Less: Earnings allocated to participating securities	(543)
Net income allocated to common shareholders	$ 360,048	$ 5,295,127
Weighted-average common shares outstanding including participating securities (in shares)	3,443,695	3,438,385
Less: Participating securities (in shares)	(4,915)	0
Less: Average unallocated ESOP Shares (in shares)	(181,887)	(68,889)
Average shares (in shares)	3,256,893	3,369,496
Basic (in dollars per share)	$ 0.11	$ 1.57
Diluted:
Net income allocated to common shareholders	$ 360,048	$ 5,295,127
Weighted-average common shares outstanding for basic earnings per common share (in shares)	3,256,893	3,369,496
Add: Dilutive effects of assumed exercises of stock options (in shares)	8,269	3,996
Average shares and dilutive potential common shares (in shares)	3,265,162	3,373,492
Diluted (in dollars per share)	$ 0.11	$ 1.57