Note 4 - Loans and Allowance for Credit Losses - Loans Individually Evaluated for Impairment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Unpaid Contractual Principal Balance	$ 2,252,362	$ 1,503,940
Recorded Investment With No Allowance	1,701,000	569,629
Recorded Investment With Allowance	551,362	934,311
Total Recorded Investment	2,252,362	1,503,940
Related Allowance	200,126	217,313
Average Recorded Investment	1,681,793	1,447,500
Unpaid Contractual Principal Balance	2,252,362	1,503,940
Recorded Investment With No Allowance	1,701,000	569,629
Recorded Investment With Allowance	551,362	934,311
Related Allowance	200,126	217,313
Average Recorded Investment	1,681,793	1,447,500
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member]
Unpaid Contractual Principal Balance	1,889,452	1,048,744
Recorded Investment With No Allowance	1,357,280	427,825
Recorded Investment With Allowance	532,172
Total Recorded Investment	1,889,452	1,048,744
Related Allowance	190,531	178,639
Average Recorded Investment	1,298,425	1,074,284
Unpaid Contractual Principal Balance	1,889,452	1,048,744
Recorded Investment With No Allowance	1,357,280	427,825
Recorded Investment With Allowance	532,172
Related Allowance	190,531	178,639
Average Recorded Investment	1,298,425	1,074,284
Residential Portfolio Segment [Member] | Multi-family Loans [Member]
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Total Recorded Investment
Related Allowance
Average Recorded Investment
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Related Allowance
Average Recorded Investment
Nonresidential Real Estate Portfolio Segment [Member]
Unpaid Contractual Principal Balance	343,720	455,196
Recorded Investment With No Allowance	343,720	141,804
Recorded Investment With Allowance		313,392
Total Recorded Investment	343,720	455,196
Related Allowance		38,674
Average Recorded Investment	377,632	366,226
Unpaid Contractual Principal Balance	343,720	455,196
Recorded Investment With No Allowance	343,720	141,804
Recorded Investment With Allowance		313,392
Related Allowance		38,674
Average Recorded Investment	377,632	366,226
Commercial Portfolio Segment [Member]
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Total Recorded Investment
Related Allowance
Average Recorded Investment		1,282
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Related Allowance
Average Recorded Investment		1,282
Consumer Portfolio Segment [Member]
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Total Recorded Investment
Related Allowance
Average Recorded Investment
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance
Related Allowance
Average Recorded Investment
Purchased Auto Loans [Member]
Unpaid Contractual Principal Balance	19,190
Recorded Investment With No Allowance
Recorded Investment With Allowance	19,190
Total Recorded Investment	19,190
Related Allowance	9,595
Average Recorded Investment	5,736	5,708
Unpaid Contractual Principal Balance	19,190
Recorded Investment With No Allowance
Recorded Investment With Allowance	19,190
Related Allowance	9,595
Average Recorded Investment	$ 5,736	$ 5,708