Note 8 - Earnings Per Share - Calculation of Diluted Weighted-average Shares Outstanding (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic:
Net income	$ 41,208	$ 370,627
Less: Earnings allocated to participating securities	(643)	(8,495)
Net income allocated to common shareholders	$ 40,565	$ 362,132
Weighted-average common shares outstanding including participating securities (in shares)	3,360,612	3,444,390
Less: Average participating securities (in shares)	(49,798)	(74,907)
Less: Average unallocated ESOP Shares (in shares)	(170,316)	(176,102)
Average shares (in shares)	3,140,499	3,193,381
Basic (in dollars per share)	$ 0.01	$ 0.11
Diluted:
Net income allocated to common shareholders	$ 40,565	$ 362,132
Average shares (in shares)	3,140,499	3,193,381
Add: Dilutive effects of assumed exercises of stock options (in shares)	4,712	13,745
Weighted average shares and dilutive potential common shares (in shares)	3,145,210	3,207,126
Diluted (in dollars per share)	$ 0.01	$ 0.11