Note 4 - Loans and Allowance for Loan Losses - Loans by Aging (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Loans receivable, past due	$ 13,780,000	$ 13,504,000
Loans receivable, current	741,373,000	739,904,000
Loans receivable	755,152,828	753,408,413
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	3,005,000	2,752,000
Loans receivable, current	111,701,000	113,047,000
Loans receivable	114,706,270	115,799,200
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	88,353,000	90,029,000
Loans receivable	88,353,385	90,028,775
Loans receivable, past due and accruing	0	0
Real Estate, Construction [Member]
Loans receivable, past due	5,242,000	5,428,000
Loans receivable, current	80,470,000	65,419,000
Loans receivable	85,711,951	70,847,330
Loans receivable, past due and accruing	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	518,000	501,000
Loans receivable, current	308,143,000	305,172,000
Loans receivable	308,660,565	305,673,212
Loans receivable, past due and accruing	0	0
Commercial Portfolio Segment [Member]
Loans receivable, past due	4,839,000	4,791,000
Loans receivable, current	128,238,000	139,535,000
Loans receivable	133,076,722	144,326,350
Loans receivable, past due and accruing	0	0
Consumer and Other Loans [Member]
Loans receivable, past due	176,000	32,000
Loans receivable, current	24,468,000	26,702,000
Loans receivable	24,643,935	26,733,546
Loans receivable, past due and accruing	0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Loans receivable, past due	766,000	2,142,000
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	529,000	623,000
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	133,000	1,239,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	17,000	264,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	55,000	6,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	32,000	10,000
Financial Asset, 60 to 89 Days Past Due [Member]
Loans receivable, past due	361,000	1,136,000
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	237,000	1,058,000
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	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	0	76,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	0	1,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	124,000	1,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans receivable, past due	12,653,000	10,226,000
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	2,239,000	1,071,000
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	5,109,000	4,189,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, past due	501,000	161,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans receivable, past due	4,784,000	4,784,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer and Other Loans [Member]
Loans receivable, past due	$ 20,000	$ 21,000