Note 3 - Loans Held for Investment, Net - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Ending balance: individually evaluated for impairment									$ 215,000	$ 0
Ending balance: collectively evaluated for impairment									3,018,813	3,117,190
Total, allowance for loan losses	$ 3,233,813	$ 3,122,170	$ 3,117,190	$ 2,919,733	$ 2,763,483	$ 2,506,033	$ 3,233,813	$ 2,506,033	3,233,813	3,117,190
Ending balance: individually evaluated for impairment, gross loans									5,344,477	5,436,972
Ending balance: collectively evaluated for impairment, gross loans									279,213,287	256,585,536
Total, gross loans									284,557,764	262,022,508
Balance	3,199,420	3,122,170	3,117,190	2,919,733	2,763,483	2,506,033	3,117,190	2,506,033
Provision for loan losses		71,000	22,000	150,000	150,000	250,000	93,000	550,000
Charge-offs	(12,827)		(23,269)	(8,850)
Recoveries	47,220	6,250	6,249	6,250	6,250	7,450
Net recoveries (charge-offs)	34,393	6,250	(17,020)	(2,600)	6,250	7,450
Balance	3,233,813	3,199,420	3,122,170	3,067,133	2,919,733	2,763,483	3,233,813	3,067,133
Commercial Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment									215,000	0
Ending balance: collectively evaluated for impairment									2,036,429	2,055,911
Total, allowance for loan losses	2,251,429	2,066,285	2,055,911	1,884,249	1,809,806	1,688,448	2,251,429	1,688,448	2,251,429	2,055,911
Ending balance: individually evaluated for impairment, gross loans									3,571,208	3,483,078
Ending balance: collectively evaluated for impairment, gross loans									227,731,922	211,388,710
Total, gross loans									231,303,130	214,871,788
Balance	2,143,311	2,066,285	2,055,911	1,884,249	1,809,806	1,688,448	2,055,911	1,688,448
Provision for loan losses	108,118	77,026	10,374	40,533	74,443	120,158
Charge-offs
Recoveries						1,200
Net recoveries (charge-offs)						1,200
Balance	2,251,429	2,143,311	2,066,285	1,924,782	1,884,249	1,809,806	2,251,429	1,924,782
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Ending balance: individually evaluated for impairment									0	0
Ending balance: collectively evaluated for impairment									380,114	567,290
Total, allowance for loan losses	380,114	503,295	567,290	599,595	627,650	617,912	380,114	617,912	380,114	567,290
Ending balance: individually evaluated for impairment, gross loans									663,580	679,184
Ending balance: collectively evaluated for impairment, gross loans									29,474,678	28,434,876
Total, gross loans									30,138,258	29,114,060
Balance	487,380	503,295	567,290	599,595	627,650	617,912	567,290	617,912
Provision for loan losses	(94,439)	(22,165)	(46,975)	(41,718)	(34,305)	3,488
Charge-offs	(12,827)		(23,269)	(8,850)
Recoveries		6,250	6,249	6,250	6,250	6,250
Net recoveries (charge-offs)	(12,827)	6,250	(17,020)	(2,600)	6,250	6,250
Balance	380,114	487,380	503,295	555,277	599,595	627,650	380,114	555,277
Commercial and Industrial Portfolio Segment [Member]
Ending balance: individually evaluated for impairment									0	0
Ending balance: collectively evaluated for impairment									559,494	462,406
Total, allowance for loan losses	559,494	514,307	462,406	408,868	299,768	147,371	559,494	147,371	559,494	462,406
Ending balance: individually evaluated for impairment, gross loans									1,109,689	1,274,710
Ending balance: collectively evaluated for impairment, gross loans									15,451,303	11,021,598
Total, gross loans									16,560,992	12,296,308
Balance	527,445	514,307	462,406	408,868	299,768	147,371	462,406	147,371
Provision for loan losses	(15,171)	13,138	51,901	151,058	109,100	152,397
Charge-offs
Recoveries	47,220
Net recoveries (charge-offs)	47,220
Balance	559,494	527,445	514,307	559,926	408,868	299,768	559,494	559,926
Consumer and Other Portfolio Segment [Member]
Ending balance: individually evaluated for impairment									0	0
Ending balance: collectively evaluated for impairment									42,776	31,583
Total, allowance for loan losses	42,776	38,283	31,583	27,021	26,259	52,302	42,776	52,302	42,776	31,583
Ending balance: individually evaluated for impairment, gross loans									0
Ending balance: collectively evaluated for impairment, gross loans									6,555,384	5,740,352
Total, gross loans									$ 6,555,384	$ 5,740,352
Balance	41,284	38,283	31,583	27,021	26,259	52,302	31,583	52,302
Provision for loan losses	1,492	3,001	6,700	127	762	(26,043)
Charge-offs
Recoveries
Net recoveries (charge-offs)
Balance	$ 42,776	$ 41,284	$ 38,283	$ 27,148	$ 27,021	$ 26,259	$ 42,776	$ 27,148