Note 4 - Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance, beginning of year				$ 7,107,418				$ 5,742,000	$ 7,107,418	$ 5,742,000	$ 5,812,000
Provision for Loan Losses	$ 300,000	$ 200,000	$ 500,000	225,000	$ 250,000	$ 450,000	$ 575,000	475,000	1,225,000	1,750,000	1,375,000
Losses charged off									(537,000)	(536,000)	(1,699,000)
Recoveries									201,000	151,000	254,000
Balance, end of year	7,995,569				7,107,418				7,995,569	7,107,418	5,742,000
Ending balance: individually evaluated for impairment	1,612,000				1,249,000				1,612,000	1,249,000	602,000
Ending balance: collectively evaluated for impairment	6,384,000				5,858,000				6,384,000	5,858,000	5,140,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	17,379,000				10,827,000				17,379,000	10,827,000	8,699,000
Ending balance: collectively evaluated for impairment	766,343,000				626,548,000				766,343,000	626,548,000	535,699,000
Ending balance: loans acquired with deteriorated credit quality	3,173,000								3,173,000
Real Estate, Construction [Member]
Balance, beginning of year				2,244,000				1,377,000	2,244,000	1,377,000	1,246,000
Provision for Loan Losses									(35,000)	793,000	1,262,000
Losses charged off											(1,222,000)
Recoveries									97,000	74,000	91,000
Balance, end of year	2,306,000				2,244,000				2,306,000	2,244,000	1,377,000
Ending balance: individually evaluated for impairment	552,000				738,000				552,000	738,000	302,000
Ending balance: collectively evaluated for impairment	1,754,000				1,506,000				1,754,000	1,506,000	1,075,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	4,088,000				4,452,000				4,088,000	4,452,000	5,447,000
Ending balance: collectively evaluated for impairment	84,507,000				60,292,000				84,507,000	60,292,000	35,465,000
Ending balance: loans acquired with deteriorated credit quality
Commercial Real Estate Portfolio Segment [Member]
Balance, beginning of year				1,789,000				1,687,000	1,789,000	1,687,000	1,526,000
Provision for Loan Losses									339,000		198,000
Losses charged off									(37,000)		(69,000)
Recoveries									2,000		32,000
Balance, end of year	2,093,000				1,789,000				2,093,000	1,789,000	1,687,000
Ending balance: individually evaluated for impairment	106,000								106,000
Ending balance: collectively evaluated for impairment	1,987,000								1,987,000		1,687,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	1,588,000								1,588,000		161,000
Ending balance: collectively evaluated for impairment	317,488,000								317,488,000		249,420,000
Ending balance: loans acquired with deteriorated credit quality	2,782,000								2,782,000
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Balance, beginning of year				1,789,000				1,687,000	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					1,789,000	1,687,000
Ending balance: individually evaluated for impairment					0					0
Ending balance: collectively evaluated for impairment					1,789,000					1,789,000
Ending balance: individually evaluated for impairment					161,000					161,000
Ending balance: collectively evaluated for impairment					261,705,000					261,705,000
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Balance, beginning of year				946,000				856,000	946,000	856,000	821,000
Provision for Loan Losses									327,000	82,000	48,000
Losses charged off									(8,000)	(11,000)	(47,000)
Recoveries									32,000	19,000	34,000
Balance, end of year	1,297,000				946,000				1,297,000	946,000	856,000
Ending balance: individually evaluated for impairment	573,000				127,000				573,000	127,000	14,000
Ending balance: collectively evaluated for impairment	724,000				819,000				724,000	819,000	842,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	4,520,000				4,424,000				4,520,000	4,424,000	2,060,000
Ending balance: collectively evaluated for impairment	128,258,000				101,877,000				128,258,000	101,877,000	104,351,000
Ending balance: loans acquired with deteriorated credit quality
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Balance, beginning of year				464,000				206,000	464,000	206,000	177,000
Provision for Loan Losses									177,000	258,000	29,000
Losses charged off									0	0	0
Recoveries									0	0	0
Balance, end of year	641,000				464,000				641,000	464,000	206,000
Ending balance: individually evaluated for impairment					0					0
Ending balance: collectively evaluated for impairment	641,000				464,000				641,000	464,000	206,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	5,952,000				775,000				5,952,000	775,000
Ending balance: collectively evaluated for impairment	84,663,000				84,450,000				84,663,000	84,450,000	48,483,000
Ending balance: loans acquired with deteriorated credit quality
Commercial Portfolio Segment [Member]
Balance, beginning of year				1,031,000				1,168,000	1,031,000	1,168,000	1,382,000
Provision for Loan Losses									222,000	91,000	(51,000)
Losses charged off									(110,000)	(240,000)	(171,000)
Recoveries									17,000	12,000	8,000
Balance, end of year	1,160,000				1,031,000				1,160,000	1,031,000	1,168,000
Ending balance: individually evaluated for impairment	363,000				246,000				363,000	246,000	241,000
Ending balance: collectively evaluated for impairment	797,000				785,000				797,000	785,000	927,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	1,062,000				739,000				1,062,000	739,000	925,000
Ending balance: collectively evaluated for impairment	118,459,000				93,784,000				118,459,000	93,784,000	74,480,000
Ending balance: loans acquired with deteriorated credit quality	216,000								216,000
Consumer Portfolio Segment [Member]
Balance, beginning of year				454,000				337,000	454,000	337,000	223,000
Provision for Loan Losses									248,000	284,000	215,000
Losses charged off									(382,000)	(213,000)	(190,000)
Recoveries									53,000	46,000	89,000
Balance, end of year	373,000				454,000				373,000	454,000	337,000
Ending balance: individually evaluated for impairment	18,000				138,000				18,000	138,000	45,000
Ending balance: collectively evaluated for impairment	355,000				316,000				355,000	316,000	292,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment	169,000				276,000				169,000	276,000	106,000
Ending balance: collectively evaluated for impairment	32,968,000				24,440,000				32,968,000	24,440,000	23,500,000
Ending balance: loans acquired with deteriorated credit quality	175,000								175,000
Unallocated Financing Receivables [Member]
Balance, beginning of year				$ 179,000				$ 111,000	179,000	111,000	437,000
Provision for Loan Losses									(53,000)	68,000	(326,000)
Losses charged off									0	0	0
Recoveries									0	0	0
Balance, end of year	126,000				179,000				126,000	179,000	111,000
Ending balance: individually evaluated for impairment					0					0
Ending balance: collectively evaluated for impairment	126,000				179,000				126,000	179,000	111,000
Ending balance: loans acquired with deteriorated credit quality
Ending balance: individually evaluated for impairment					0					0
Ending balance: collectively evaluated for impairment					$ 0					$ 0
Ending balance: loans acquired with deteriorated credit quality