Note 5 - Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Balance, beginning of period	$ 8,788,000	$ 7,671,000	$ 7,607,587	$ 7,996,000
Provision for loan losses	950,000	100,000	2,200,000	200,000
Losses charged off	(80,000)	(313,000)	(225,000)	(973,000)
Recoveries	23,000	99,000	98,000	334,000
Balance, end of period	9,680,688	7,557,000	9,680,688	7,557,000
Ending balance: individually evaluated for impairment	1,288,000		1,288,000		$ 1,094,000
Ending balance: collectively evaluated for impairment	8,392,000		8,392,000		6,514,000
Ending balance: loans acquired with deteriorated credit quality	1,000		1,000		0
Ending balance: individually evaluated for impairment	8,748,000		8,748,000		9,133,000
Ending balance: collectively evaluated for impairment	771,880,000		771,880,000		716,946,000
Ending balance: loans acquired with deteriorated credit quality	2,650,000		2,650,000		2,835,000
Real Estate, Construction [Member]
Balance, beginning of period	1,569,000	2,169,000	1,749,000	2,306,000
Provision for loan losses	53,000	(245,000)	(127,000)	(523,000)
Losses charged off	0	0	0	0
Recoveries	0	28,000	0	169,000
Balance, end of period	1,622,000	1,952,000	1,622,000	1,952,000
Ending balance: individually evaluated for impairment	626,000		626,000		553,000
Ending balance: collectively evaluated for impairment	996,000		996,000		1,196,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	4,437,000		4,437,000		4,742,000
Ending balance: collectively evaluated for impairment	65,479,000		65,479,000		72,567,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Commercial Real Estate Portfolio Segment [Member]
Balance, beginning of period	2,998,000	2,188,000
Provision for loan losses	270,000	242,000
Losses charged off	0	(122,000)
Recoveries	1,000	1,000
Balance, end of period	3,269,000	2,309,000	3,269,000	2,309,000
Ending balance: individually evaluated for impairment	95,000		95,000		24,000
Ending balance: collectively evaluated for impairment	3,174,000		3,174,000		2,243,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	1,023,000		1,023,000		650,000
Ending balance: collectively evaluated for impairment	301,025,000		301,025,000		297,318,000
Ending balance: loans acquired with deteriorated credit quality	2,507,000		2,507,000		2,651,000
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Balance, beginning of period			2,267,000	2,093,000
Provision for loan losses			995,000	317,000
Losses charged off			0	(122,000)
Recoveries			7,000	21,000
Balance, end of period	3,269,000	2,309,000	3,269,000	2,309,000
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Balance, beginning of period	1,539,000	948,000	1,001,000	1,297,000
Provision for loan losses	(30,000)	42,000	508,000	(41,000)
Losses charged off	(1,000)	0	(1,000)	(271,000)
Recoveries	1,000	1,000	1,000	6,000
Balance, end of period	1,509,000	991,000	1,509,000	991,000
Ending balance: individually evaluated for impairment	249,000		249,000		197,000
Ending balance: collectively evaluated for impairment	1,260,000		1,260,000		804,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	2,380,000		2,380,000		2,613,000
Ending balance: collectively evaluated for impairment	126,088,000		126,088,000		116,211,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Balance, beginning of period	794,000	673,000	746,000	641,000
Provision for loan losses	126,000	50,000	174,000	82,000
Losses charged off	0	0	0	0
Recoveries	0	0	0	0
Balance, end of period	920,000	723,000	920,000	723,000
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	920,000		920,000		746,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	89,763,000		89,763,000		87,448,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Commercial Portfolio Segment [Member]
Balance, beginning of period	1,299,000	1,236,000	1,129,000	1,160,000
Provision for loan losses	158,000	(125,000)	325,000	175,000
Losses charged off	(17,000)	(106,000)	(49,000)	(381,000)
Recoveries	3,000	55,000	38,000	106,000
Balance, end of period	1,443,000	1,060,000	1,443,000	1,060,000
Ending balance: individually evaluated for impairment	300,000		300,000		299,000
Ending balance: collectively evaluated for impairment	1,142,000		1,142,000		830,000
Ending balance: loans acquired with deteriorated credit quality	1,000		1,000		0
Ending balance: individually evaluated for impairment	680,000		680,000		908,000
Ending balance: collectively evaluated for impairment	162,275,000		162,275,000		112,956,000
Ending balance: loans acquired with deteriorated credit quality	143,000		143,000		184,000
Consumer Portfolio Segment [Member]
Balance, beginning of period	466,000	397,000	443,000	373,000
Provision for loan losses	41,000	99,000	143,000	219,000
Losses charged off	(62,000)	(85,000)	(175,000)	(199,000)
Recoveries	18,000	14,000	52,000	32,000
Balance, end of period	463,000	425,000	463,000	425,000
Consumer and Other Loans [Member]
Ending balance: individually evaluated for impairment	18,000		18,000		21,000
Ending balance: collectively evaluated for impairment	445,000		445,000		422,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	228,000		228,000		220,000
Ending balance: collectively evaluated for impairment	27,251,000		27,251,000		30,446,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Unallocated Financing Receivables [Member]
Balance, beginning of period	123,000	60,000	273,000	126,000
Provision for loan losses	332,000	37,000	182,000	(29,000)
Losses charged off	0	0	0	0
Recoveries	0	0	0	0
Balance, end of period	455,000	$ 97,000	455,000	$ 97,000
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	455,000		455,000		273,000
Ending balance: loans acquired with deteriorated credit quality	0		0		0
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	0		0		0
Ending balance: loans acquired with deteriorated credit quality	$ 0		$ 0		$ 0