Note 4 - Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance, beginning of year				$ 7,995,569				$ 7,107,000	$ 7,995,569	$ 7,107,000	$ 5,742,000
Provision for Loan Losses	$ 0	$ 100,000	$ 100,000	0	$ 300,000	$ 200,000	$ 500,000	225,000	200,000	1,225,000	1,750,000
Losses charged off									(1,055,000)	(537,000)	(536,000)
Recoveries									467,000	201,000	151,000
Balance, end of year	7,607,587				7,995,569				7,607,587	7,995,569	7,107,000
Ending balance: individually evaluated for impairment	1,094,000				1,612,000				1,094,000	1,612,000	1,249,000
Ending balance: collectively evaluated for impairment	6,514,000				6,384,000				6,514,000	6,384,000	5,858,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	9,133,000				17,379,000				9,133,000	17,379,000	10,827,000
Ending balance: collectively evaluated for impairment	716,946,000				766,343,000				716,946,000	766,343,000	626,548,000
Carrying amount, net of fair value adjustment	2,835,000				3,173,000				2,835,000	3,173,000
Real Estate, Construction [Member]
Balance, beginning of year				2,306,000				2,244,000	2,306,000	2,244,000	1,377,000
Provision for Loan Losses									(809,000)	(35,000)	793,000
Losses charged off
Recoveries									252,000	97,000	74,000
Balance, end of year	1,749,000				2,306,000				1,749,000	2,306,000	2,244,000
Ending balance: individually evaluated for impairment	553,000				552,000				553,000	552,000	738,000
Ending balance: collectively evaluated for impairment	1,196,000				1,754,000				1,196,000	1,754,000	1,506,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	4,742,000				4,088,000				4,742,000	4,088,000	4,452,000
Ending balance: collectively evaluated for impairment	72,567,000				84,507,000				72,567,000	84,507,000	60,292,000
Carrying amount, net of fair value adjustment
Commercial Real Estate Portfolio Segment [Member]
Balance, beginning of year				2,093,000				1,789,000	2,093,000	1,789,000
Provision for Loan Losses									265,000	339,000
Losses charged off									(122,000)	(37,000)
Recoveries									31,000	2,000
Balance, end of year	2,267,000				2,093,000				2,267,000	2,093,000	1,789,000
Ending balance: individually evaluated for impairment	24,000				106,000				24,000	106,000
Ending balance: collectively evaluated for impairment	2,243,000				1,987,000				2,243,000	1,987,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	650,000				1,588,000				650,000	1,588,000
Ending balance: collectively evaluated for impairment	297,318,000				317,488,000				297,318,000	317,488,000
Carrying amount, net of fair value adjustment	2,651,000				2,782,000				2,651,000	2,782,000
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Balance, beginning of year								1,789,000		1,789,000	1,687,000
Provision for Loan Losses											174,000
Losses charged off											(72,000)
Recoveries
Balance, end of year											1,789,000
Ending balance: individually evaluated for impairment											0
Ending balance: collectively evaluated for impairment											1,789,000
Ending balance: individually evaluated for impairment											161,000
Ending balance: collectively evaluated for impairment											261,705,000
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Balance, beginning of year				1,297,000				946,000	1,297,000	946,000	856,000
Provision for Loan Losses									(32,000)	327,000	82,000
Losses charged off									(272,000)	(8,000)	(11,000)
Recoveries									8,000	32,000	19,000
Balance, end of year	1,001,000				1,297,000				1,001,000	1,297,000	946,000
Ending balance: individually evaluated for impairment	197,000				573,000				197,000	573,000	127,000
Ending balance: collectively evaluated for impairment	804,000				724,000				804,000	724,000	819,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	2,613,000				4,520,000				2,613,000	4,520,000	4,424,000
Ending balance: collectively evaluated for impairment	116,211,000				128,258,000				116,211,000	128,258,000	101,877,000
Carrying amount, net of fair value adjustment
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Balance, beginning of year				641,000				464,000	641,000	464,000	206,000
Provision for Loan Losses									105,000	177,000	258,000
Losses charged off									0	0	0
Recoveries									0	0	0
Balance, end of year	746,000				641,000				746,000	641,000	464,000
Ending balance: individually evaluated for impairment											0
Ending balance: collectively evaluated for impairment	746,000				641,000				746,000	641,000	464,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment					5,952,000					5,952,000	775,000
Ending balance: collectively evaluated for impairment	87,448,000				84,663,000				87,448,000	84,663,000	84,450,000
Carrying amount, net of fair value adjustment
Commercial Portfolio Segment [Member]
Balance, beginning of year				1,160,000				1,031,000	1,160,000	1,031,000	1,168,000
Provision for Loan Losses									225,000	222,000	91,000
Losses charged off									(381,000)	(110,000)	(240,000)
Recoveries									125,000	17,000	12,000
Balance, end of year	1,129,000				1,160,000				1,129,000	1,160,000	1,031,000
Ending balance: individually evaluated for impairment	299,000				363,000				299,000	363,000	246,000
Ending balance: collectively evaluated for impairment	830,000				797,000				830,000	797,000	785,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	908,000				1,062,000				908,000	1,062,000	739,000
Ending balance: collectively evaluated for impairment	112,956,000				118,459,000				112,956,000	118,459,000	93,784,000
Carrying amount, net of fair value adjustment	184,000				216,000				184,000	216,000
Consumer Portfolio Segment [Member]
Balance, beginning of year				373,000				454,000	373,000	454,000	337,000
Provision for Loan Losses									299,000	248,000	284,000
Losses charged off									(280,000)	(382,000)	(213,000)
Recoveries									51,000	53,000	46,000
Balance, end of year	443,000				373,000				443,000	373,000	454,000
Ending balance: individually evaluated for impairment	21,000				18,000				21,000	18,000	138,000
Ending balance: collectively evaluated for impairment	422,000				355,000				422,000	355,000	316,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	220,000				169,000				220,000	169,000	276,000
Ending balance: collectively evaluated for impairment	30,446,000				32,968,000				30,446,000	32,968,000	24,440,000
Carrying amount, net of fair value adjustment					175,000					175,000
Unallocated Financing Receivables [Member]
Balance, beginning of year				$ 126,000				$ 179,000	126,000	179,000	111,000
Provision for Loan Losses									147,000	(53,000)	68,000
Losses charged off									0	0	0
Recoveries									0	0	0
Balance, end of year	273,000				126,000				273,000	126,000	179,000
Ending balance: individually evaluated for impairment											0
Ending balance: collectively evaluated for impairment	273,000				126,000				273,000	126,000	179,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment											0
Ending balance: collectively evaluated for impairment											$ 0
Carrying amount, net of fair value adjustment