Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Balance			$ 7,925	$ 8,300	$ 8,300
Charge-offs			(487)	(689)	(819)
Recoveries			182	138	287
Provision for loan losses	$ 223	$ 201	93	724	157
Balance	7,713	8,473	7,713	8,473	7,925
Real Estate Construction Portfolio Segment[Member]
Balance			337	438	438
Charge-offs			0
Recoveries			0	0	0
Provision for loan losses			137	(140)	(101)
Balance	474	298	474	298	337
Consumer Real Estate Portfolio Segment [Member]
Balance			2,027	1,830	1,830
Charge-offs			(36)	(146)	(146)
Recoveries			2	1	1
Provision for loan losses			185	337	342
Balance	2,178	2,022	2,178	2,022	2,027
Commercial Real Estate Portfolio Segment [Member]
Balance			3,044	3,738	3,738
Charge-offs				(122)	(139)
Recoveries			37	44	131
Provision for loan losses			(42)	33	(686)
Balance	3,039	3,693	3,039	3,693	3,044
Commercial Non Real Estate Segment [Member]
Balance			1,072	1,063	1,063
Charge-offs			(107)	(73)	(82)
Recoveries			22	14	23
Provision for loan losses			(305)	111	68
Balance	682	1,115	682	1,115	1,072
Public Sector and IDA Portfolio Segment[Member]
Balance			419	330	330
Charge-offs			0	0	0
Recoveries			0	0	0
Provision for loan losses			151	55	89
Balance	570	385	570	385	419
Consumer Non Real Estate Portfolio Segment [Member]
Balance			707	644	644
Charge-offs			(344)	(348)	(452)
Recoveries			121	79	132
Provision for loan losses			240	357	383
Balance	724	732	724	732	707
Unallocated Financing Receivables [Member]
Balance			319	257	257
Charge-offs			0	0	0
Recoveries			0	0	0
Provision for loan losses			(273)	(29)	62
Balance	$ 46	$ 228	$ 46	$ 228	$ 319