Note 4 - Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Balance, beginning of period	$ 9,617,024	$ 7,608,000
Provision for loan losses	400,000	500,000
Losses charged off	(158,000)	(94,000)
Recoveries	29,000	35,000
Balance, end of period	9,887,939	8,049,000
Ending balance: individually evaluated for impairment	354,000		$ 420,000
Ending balance: collectively evaluated for impairment	9,534,000		9,196,000
Ending balance: loans acquired with deteriorated credit quality	0		1,000
Ending balance: individually evaluated for impairment	15,662,000		16,472,000
Ending balance: collectively evaluated for impairment	737,035,000		734,394,000
Ending balance: loans acquired with deteriorated credit quality	2,456,000		2,542,000
Real Estate, Construction [Member]
Balance, beginning of period	1,132,000	1,749,000
Provision for loan losses	363,000	(120,000)
Losses charged off	(121,000)	0
Recoveries	0	0
Balance, end of period	1,374,000	1,629,000
Ending balance: individually evaluated for impairment	109,000		114,000
Ending balance: collectively evaluated for impairment	1,265,000		1,018,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	5,948,000		6,239,000
Ending balance: collectively evaluated for impairment	79,764,000		64,608,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Commercial Real Estate Portfolio Segment [Member]
Balance, beginning of period	3,624,000	2,267,000
Provision for loan losses	206,000	304,000
Losses charged off	0	0
Recoveries	1,000	6,000
Balance, end of period	3,831,000	2,577,000
Ending balance: individually evaluated for impairment	107,000		117,000
Ending balance: collectively evaluated for impairment	3,724,000		3,507,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	1,797,000		1,810,000
Ending balance: collectively evaluated for impairment	304,530,000		301,453,000
Ending balance: loans acquired with deteriorated credit quality	2,334,000		2,410,000
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Balance, beginning of period	1,445,000	1,001,000
Provision for loan losses	(23,000)	152,000
Losses charged off	0	0
Recoveries	4,000	1,000
Balance, end of period	1,426,000	1,154,000
Ending balance: individually evaluated for impairment	64,000		112,000
Ending balance: collectively evaluated for impairment	1,362,000		1,333,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	2,621,000		3,110,000
Ending balance: collectively evaluated for impairment	112,085,000		112,689,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Balance, beginning of period	1,058,000	746,000
Provision for loan losses	(60,000)	9,000
Losses charged off	0	0
Recoveries	0	0
Balance, end of period	998,000	755,000
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	998,000		1,058,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	88,353,000		90,029,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Commercial Portfolio Segment [Member]
Balance, beginning of period	1,129,000	1,129,000
Provision for loan losses	122,000	237,000
Losses charged off	0	(32,000)
Recoveries	6,000	15,000
Balance, end of period	1,257,000	1,349,000
Ending balance: individually evaluated for impairment	61,000		62,000
Ending balance: collectively evaluated for impairment	1,196,000		1,066,000
Ending balance: loans acquired with deteriorated credit quality	0		1,000
Ending balance: individually evaluated for impairment	5,105,000		5,111,000
Ending balance: collectively evaluated for impairment	127,850,000		139,083,000
Ending balance: loans acquired with deteriorated credit quality	122,000		132,000
Consumer Portfolio Segment [Member]
Balance, beginning of period	571,000	443,000
Provision for loan losses	(158,000)	55,000
Losses charged off	(37,000)	(62,000)
Recoveries	18,000	13,000
Balance, end of period	394,000	449,000
Ending balance: individually evaluated for impairment	13,000		15,000
Ending balance: collectively evaluated for impairment	381,000		556,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	191,000		202,000
Ending balance: collectively evaluated for impairment	24,453,000		26,532,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Unallocated Financing Receivables [Member]
Balance, beginning of period	658,000	273,000
Provision for loan losses	(50,000)	(137,000)
Losses charged off	0	0
Recoveries	0	0
Balance, end of period	608,000	$ 136,000
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	608,000		658,000
Ending balance: loans acquired with deteriorated credit quality	0		0
Ending balance: individually evaluated for impairment	0		0
Ending balance: collectively evaluated for impairment	0		0
Ending balance: loans acquired with deteriorated credit quality	$ 0		$ 0