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Note 6 - Loans Receivable, Net and Allowance for Loan Losses - Composition of Net Loans Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Loans	$ 350,867		$ 249,767
Deferred loan fees and costs	(2,955)		(844)
Allowance for loan losses	(2,852)	$ (2,651)	(2,231)	$ (2,283)	$ (2,126)	$ (1,965)
Net Loans	345,060		246,692
Real Estate Portfolio Segment [Member]
Loans	209,651		204,000
Real Estate Portfolio Segment [Member] \| One-to-four Family Residential Owner Occupied Loans [Member]
Loans	5,385		6,298
Allowance for loan losses	(47)	(43)	(52)	(48)	(49)	(51)
Real Estate Portfolio Segment [Member] \| One-to-four Family Residential Non-owner Occupied Loans [Member]
Loans	40,872		39,897
Allowance for loan losses	(408)	(399)	(351)	(417)	(437)	(435)
Real Estate Portfolio Segment [Member] \| One-to-four Family Residential Loans [Member]
Loans	46,257		46,195
Real Estate Portfolio Segment [Member] \| Multi-family (Five Or More) Residential Loans [Member]
Loans	22,814		22,233
Allowance for loan losses	(251)	(204)	(145)	(150)	(153)	(156)
Real Estate Portfolio Segment [Member] \| Commercial Real Estate Loans [Member]
Loans	128,965		119,323
Real Estate Portfolio Segment [Member] \| Construction Loans [Member]
Loans	7,512		12,523
Allowance for loan losses	(113)	(114)	(250)	(269)	(180)	(175)
Real Estate Portfolio Segment [Member] \| Home Equity Loan [Member]
Loans	4,103		3,726
Allowance for loan losses	(27)	$ (25)	(19)	$ (20)	$ (23)	$ (21)
Commercial Portfolio Segment [Member]
Loans	141,206		45,745
Consumer Portfolio Segment [Member]
Loans	$ 10		$ 22