Note 4 - Loans Held for Investment, Net - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Ending balance: individually evaluated for impairment								$ 3,505,288
Ending balance: collectively evaluated for impairment, allowance for loan losses							3,975,620	2,921,931
Total, allowance for loan losses	$ 3,396,861	$ 3,396,861	$ 3,068,291	$ 2,981,412	$ 2,921,931	$ 3,068,291	3,975,620	2,921,931
Ending balance: individually evaluated for impairment, allowance for loan losses							3,401,448	0
Ending balance: collectively evaluated for impairment							349,318,095	291,963,300
Total							352,719,543	295,468,588
Balance	3,396,861	2,921,931	2,981,412	2,901,091	2,921,931	2,901,091
Provision for loan losses	577,000	472,000	85,000	87,500	1,049,000	172,500
Charge-offs				(8,686)
Recoveries	1,759	2,930	1,879	1,507
Net (charge-offs) recoveries	1,759	2,930	1,879	(7,179)
Change-offs				8,686
Net (charge-offs) recoveries	1,759	2,930	1,879	(7,179)
Balance	3,975,620	3,396,861	3,068,291	2,981,412	3,975,620	3,068,291
Balance June 30, 2019	3,396,861	3,396,861	3,068,291	2,981,412	2,921,931	3,068,291	3,975,620	2,921,931
Commercial Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment								2,718,731
Ending balance: collectively evaluated for impairment, allowance for loan losses							3,371,097	2,588,714
Total, allowance for loan losses	2,856,106	2,856,106	2,426,902	2,341,297	2,588,714	2,426,902	3,371,097	2,588,714
Ending balance: individually evaluated for impairment, allowance for loan losses							2,578,003	0
Ending balance: collectively evaluated for impairment							255,298,730	239,963,990
Total							257,876,733	242,682,721
Balance	2,856,106	2,588,714	2,341,297	2,130,124	2,588,714	2,130,124
Provision for loan losses	514,991	267,392	85,605	211,173
Charge-offs
Recoveries
Net (charge-offs) recoveries
Change-offs
Net (charge-offs) recoveries
Balance	3,371,097	2,856,106	2,426,902	2,341,297	3,371,097	2,426,902
Balance June 30, 2019	2,856,106	2,856,106	2,426,902	2,341,297	2,588,714	2,426,902	3,371,097	2,588,714
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment								786,557
Ending balance: collectively evaluated for impairment, allowance for loan losses							250,674	187,345
Total, allowance for loan losses	239,647	239,647	219,630	220,139	187,345	219,630	250,674	187,345
Ending balance: individually evaluated for impairment, allowance for loan losses							823,445	0
Ending balance: collectively evaluated for impairment							23,530,642	28,063,083
Total							24,354,087	28,849,640
Balance	239,647	187,345	220,139	359,705	187,345	359,705
Provision for loan losses	9,268	49,372	(2,388)	(130,880)
Charge-offs				(8,686)
Recoveries	1,759	2,930	1,879
Net (charge-offs) recoveries	1,759	2,930	1,879	(8,686)
Change-offs				8,686
Net (charge-offs) recoveries	1,759	2,930	1,879	(8,686)
Balance	250,674	239,647	219,630	220,139	250,674	219,630
Balance June 30, 2019	239,647	239,647	219,630	220,139	187,345	219,630	250,674	187,345
Commercial and Industrial Portfolio Segment [Member]
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment, allowance for loan losses							307,805	115,502
Total, allowance for loan losses	263,483	263,483	398,339	388,425	115,502	398,339	307,805	115,502
Ending balance: individually evaluated for impairment, allowance for loan losses							0	0
Ending balance: collectively evaluated for impairment							66,761,757	20,075,236
Total							66,761,757	20,075,236
Balance	263,483	115,502	388,425	377,180	115,502	377,180
Provision for loan losses	44,322	147,981	9,914	9,738
Charge-offs
Recoveries				1,507
Net (charge-offs) recoveries				1,507
Change-offs
Net (charge-offs) recoveries				1,507
Balance	307,805	263,483	398,339	388,425	307,805	398,339
Balance June 30, 2019	263,483	263,483	398,339	388,425	115,502	398,339	307,805	115,502
Consumer and Other Portfolio Segment [Member]
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment, allowance for loan losses							46,044	30,370
Total, allowance for loan losses	37,625	37,625	23,420	31,551	30,370	23,420	46,044	30,370
Ending balance: individually evaluated for impairment, allowance for loan losses							0	0
Ending balance: collectively evaluated for impairment							3,726,966	3,860,991
Total							3,726,966	3,860,991
Balance	37,625	30,370	31,551	34,082	30,370	34,082
Provision for loan losses	8,419	7,255	(8,131)	(2,531)
Charge-offs
Recoveries
Net (charge-offs) recoveries
Change-offs
Net (charge-offs) recoveries
Balance	46,044	37,625	23,420	31,551	46,044	23,420
Balance June 30, 2019	$ 37,625	$ 37,625	$ 23,420	$ 31,551	$ 30,370	$ 23,420	$ 46,044	$ 30,370