Note 5 - Loans and Allowance for Loan Losses - Loans by Aging (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Loans receivable, past due	$ 6,984,000	$ 1,356,000
Loans receivable, current	776,294,000	727,558,000
Loans receivable	783,278,283	728,914,025
Loans receivable, past due and accruing	0	0
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	1,471,000	645,000
Loans receivable, current	126,997,000	118,179,000
Loans receivable	128,467,837	118,823,731
Loans receivable, past due and accruing	0	0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	0	0
Loans receivable, current	89,763,000	87,448,000
Loans receivable	89,762,581	87,448,418
Loans receivable, past due and accruing	0	0
Real Estate, Construction [Member]
Loans receivable, past due	4,437,000	338,000
Loans receivable, current	65,479,000	76,971,000
Loans receivable	69,915,937	77,308,551
Loans receivable, past due and accruing	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	361,000	43,000
Loans receivable, current	304,194,000	300,576,000
Loans receivable	304,555,366	300,619,387
Loans receivable, past due and accruing	0	0
Commercial Portfolio Segment [Member]
Loans receivable, past due	365,000	256,000
Loans receivable, current	162,733,000	113,792,000
Loans receivable	163,097,935	114,047,753
Loans receivable, past due and accruing	0	0
Consumer and Other Loans [Member]
Loans receivable, past due	350,000	74,000
Loans receivable, current	27,129,000	30,592,000
Loans receivable	27,478,627	30,666,185
Loans receivable, past due and accruing	0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Loans receivable, past due	332,000	603,000
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	56,000	83,000
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due	0	338,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	200,000	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	17,000	134,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	59,000	48,000
Financial Asset, 60 to 89 Days Past Due [Member]
Loans receivable, past due	1,122,000	568,000
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	311,000	437,000
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due	811,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	0	105,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	0	26,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans receivable, past due	5,530,000	185,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans receivable, past due	1,104,000	125,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans receivable, past due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Real Estate, Construction [Member]
Loans receivable, past due	3,626,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	161,000	43,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	348,000	17,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	$ 291,000	$ 0