Note 3 - Loans Held for Investment, Net - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Ending balance: individually evaluated for impairment				$ 0
Ending balance: collectively evaluated for impairment			2,981,412	2,901,091
Total, allowance for loan losses	$ 2,981,412	$ 3,117,190	2,981,412	2,901,091
Ending balance: individually evaluated for impairment, gross loans			3,605,635	3,643,608
Ending balance: collectively evaluated for impairment, gross loans			287,373,038	283,197,281
Total, gross loans			290,978,673	286,840,889
Balance	2,901,091	3,117,190
Provision for loan losses	87,500	22,000
Charge-offs	(8,686)	(23,269)
Recoveries	1,507	6,249
Net recoveries (charge-offs)	(7,179)	(17,020)
Balance	2,981,412	3,122,170
Commercial Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment				0
Ending balance: collectively evaluated for impairment			2,341,297	2,130,124
Total, allowance for loan losses	2,341,297	2,055,911	2,341,297	2,130,124
Ending balance: individually evaluated for impairment, gross loans			2,988,885	2,993,923
Ending balance: collectively evaluated for impairment, gross loans			235,131,239	230,108,714
Total, gross loans			238,120,124	233,102,637
Balance	2,130,124	2,055,911
Provision for loan losses	211,173	10,374
Charge-offs
Recoveries
Net recoveries (charge-offs)
Balance	2,341,297	2,066,285
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			220,139	359,705
Total, allowance for loan losses	220,139	567,290	220,139	359,705
Ending balance: individually evaluated for impairment, gross loans			616,750	649,685
Ending balance: collectively evaluated for impairment, gross loans			28,553,631	29,205,777
Total, gross loans			29,170,381	29,855,462
Balance	359,705	567,290
Provision for loan losses	(130,880)	(46,975)
Charge-offs	(8,686)	(23,269)
Recoveries		6,249
Net recoveries (charge-offs)	(8,686)	(17,020)
Balance	220,139	503,295
Commercial and Industrial Portfolio Segment [Member]
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			388,425	377,180
Total, allowance for loan losses	388,425	462,406	388,425	377,180
Ending balance: individually evaluated for impairment, gross loans
Ending balance: collectively evaluated for impairment, gross loans			17,602,539	17,508,258
Total, gross loans			17,602,539	17,508,258
Balance	377,180	462,406
Provision for loan losses	9,738	51,901
Charge-offs
Recoveries	1,507
Net recoveries (charge-offs)	1,507
Balance	388,425	514,307
Consumer and Other Portfolio Segment [Member]
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			31,551	34,082
Total, allowance for loan losses	31,551	31,583	31,551	34,082
Ending balance: individually evaluated for impairment, gross loans			0
Ending balance: collectively evaluated for impairment, gross loans			6,085,629	6,374,532
Total, gross loans			$ 6,085,629	$ 6,374,532
Balance	34,082	31,583
Provision for loan losses	(2,531)	6,700
Net recoveries (charge-offs)
Balance	$ 31,551	$ 38,283