Note 4 - Loans Held for Investment, Net - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Ending balance: individually evaluated for impairment, allowance for loan losses				$ 0
Ending balance: collectively evaluated for impairment, allowance for loan losses			3,396,861	2,921,931
Total, allowance for loan losses	$ 2,921,931	$ 2,981,412	3,396,861	2,921,931
Ending balance: individually evaluated for impairment			3,409,628	3,505,288
Ending balance: collectively evaluated for impairment			310,269,913	291,963,300
Total			313,679,541	295,468,588
Balance	2,921,931	2,901,091
Provision for loan losses	472,000	87,500
Charge-offs		(8,686)
Recoveries	2,930	1,507
Net recoveries (charge-offs)	2,930	(7,179)
Balance	3,396,861	2,981,412
Commercial Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment, allowance for loan losses				0
Ending balance: collectively evaluated for impairment, allowance for loan losses			2,856,106	2,588,714
Total, allowance for loan losses	2,588,714	2,341,297	2,856,106	2,588,714
Ending balance: individually evaluated for impairment			2,642,676	2,718,731
Ending balance: collectively evaluated for impairment			246,120,363	239,963,990
Total			248,763,039	242,682,721
Balance	2,588,714	2,130,124
Provision for loan losses	267,392	211,173
Recoveries
Net recoveries (charge-offs)
Balance	2,856,106	2,341,297
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment, allowance for loan losses			0	0
Ending balance: collectively evaluated for impairment, allowance for loan losses			239,647	187,345
Total, allowance for loan losses	187,345	220,139	239,647	187,345
Ending balance: individually evaluated for impairment			766,952	786,557
Ending balance: collectively evaluated for impairment			26,926,638	28,063,083
Total			27,693,590	28,849,640
Balance	187,345	359,705
Provision for loan losses	49,372	(130,880)
Charge-offs		(8,686)
Recoveries	2,930
Net recoveries (charge-offs)	2,930	(8,686)
Balance	239,647	220,139
Commercial and Industrial Portfolio Segment [Member]
Ending balance: individually evaluated for impairment, allowance for loan losses			0	0
Ending balance: collectively evaluated for impairment, allowance for loan losses			263,483	115,502
Total, allowance for loan losses	115,502	388,425	263,483	115,502
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment			34,081,604	20,075,236
Total			34,081,604	20,075,236
Balance	115,502	377,180
Provision for loan losses	147,981	9,738
Charge-offs
Recoveries		1,507
Net recoveries (charge-offs)		1,507
Balance	263,483	388,425
Consumer and Other Portfolio Segment [Member]
Ending balance: individually evaluated for impairment, allowance for loan losses			0	0
Ending balance: collectively evaluated for impairment, allowance for loan losses			37,625	30,370
Total, allowance for loan losses	30,370	31,551	37,625	30,370
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment			3,141,308	3,860,991
Total			$ 3,141,308	$ 3,860,991
Balance	30,370	34,082
Provision for loan losses	7,255	(2,531)
Balance	$ 37,625	$ 31,551