Note 4 - Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Balance	$ 7,107,418	$ 5,742,000
Provision for loan losses	225,000	475,000
Losses charged off	(264,000)	(81,000)
Recoveries	35,000	36,000
Balance	7,102,712	6,172,000
Ending balance: individually evaluated for impairment	1,272,000		$ 1,249,000
Ending balance: collectively evaluated for impairment	5,831,000		5,858,000
Ending balance: individually evaluated for impairment	10,273,000		10,827,000
Ending balance: collectively evaluated for impairment	635,433,000		626,548,000
Real Estate, Construction [Member]
Balance	2,244,000	1,377,000
Provision for loan losses	(40,000)	(96,000)
Losses charged off
Recoveries	19,000	18,000
Balance	2,223,000	1,299,000
Ending balance: individually evaluated for impairment	741,000		738,000
Ending balance: collectively evaluated for impairment	1,482,000		1,506,000
Ending balance: individually evaluated for impairment	4,354,000		4,452,000
Ending balance: collectively evaluated for impairment	76,875,000		60,292,000
Commercial Real Estate Portfolio Segment [Member]
Balance	1,789,000
Provision for loan losses	87,000
Losses charged off
Recoveries
Balance	1,876,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	1,876,000		1,789,000
Ending balance: individually evaluated for impairment	161,000		161,000
Ending balance: collectively evaluated for impairment	254,555,000		261,705,000
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Balance		1,687,000
Provision for loan losses		55,000
Losses charged off
Recoveries
Balance		1,742,000
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Balance	946,000	856,000
Provision for loan losses	167,000	(33,000)
Losses charged off		(11,000)
Recoveries		6,000
Balance	1,113,000	818,000
Ending balance: individually evaluated for impairment	302,000		127,000
Ending balance: collectively evaluated for impairment	811,000		819,000
Ending balance: individually evaluated for impairment	4,259,000		4,424,000
Ending balance: collectively evaluated for impairment	101,581,000		101,877,000
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Balance	464,000	206,000
Provision for loan losses	23,000	67,000
Losses charged off	0	0
Recoveries	0	0
Balance	487,000	273,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	487,000		464,000
Ending balance: individually evaluated for impairment	762,000		775,000
Ending balance: collectively evaluated for impairment	81,221,000		84,450,000
Commercial Portfolio Segment [Member]
Balance	1,031,000	1,168,000
Provision for loan losses	20,000	(287,000)
Losses charged off	(96,000)
Recoveries	3,000	2,000
Balance	958,000	883,000
Ending balance: individually evaluated for impairment	219,000		246,000
Ending balance: collectively evaluated for impairment	739,000		785,000
Ending balance: individually evaluated for impairment	656,000		739,000
Ending balance: collectively evaluated for impairment	97,174,000		93,784,000
Consumer and Other Loans [Member]
Balance	454,000	337,000
Provision for loan losses	(8,000)	5,000
Losses charged off	(168,000)	(70,000)
Recoveries	13,000	10,000
Balance	291,000	282,000
Ending balance: individually evaluated for impairment	10,000		138,000
Ending balance: collectively evaluated for impairment	281,000		316,000
Ending balance: individually evaluated for impairment	81,000		276,000
Ending balance: collectively evaluated for impairment	24,027,000		24,440,000
Unallocated Financing Receivables [Member]
Balance	179,000
Provision for loan losses	(24,000)
Losses charged off	0
Recoveries	0
Balance	155,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	155,000		179,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment
Unallocated [Member]
Balance		111,000
Provision for loan losses		764,000
Losses charged off		0
Recoveries		0
Balance		$ 875,000