Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Impaired Loans and Associated Reserves (Details) - USD ($) $ in Thousands		Sep. 30, 2018		Dec. 31, 2017		Sep. 30, 2017
Principal balance		$ 12,376		$ 12,319
Total recorded investment		11,934	[1]	11,924	[1]	$ 12,159
Recorded investment for which there is no related allowance		10,530	[1]	10,444	[1]	10,522
Recorded investment for which there is a related allowance		1,404	[1]	1,480	[1]	1,637
Related allowance		156		177		$ 186
Real Estate Construction Portfolio Segment[Member] | Construction, Other [Member]
Principal balance	[2]	2,470
Total recorded investment	[1],[2]	2,470
Recorded investment for which there is no related allowance	[1],[2]	2,470
Recorded investment for which there is a related allowance	[1],[2]	0
Related allowance	[2]	0
Real Estate Construction Portfolio Segment[Member] | Construction, 1-4 Family Residential [Member]
Principal balance	[2]			2,882
Total recorded investment	[1],[2]			2,882
Recorded investment for which there is no related allowance	[1],[2]			2,882
Recorded investment for which there is a related allowance	[1],[2]			0
Related allowance	[2]			0
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member]
Principal balance	[2]	928		807
Total recorded investment	[1],[2]	882		768
Recorded investment for which there is no related allowance	[1],[2]	707		590
Recorded investment for which there is a related allowance	[1],[2]	175		178
Related allowance	[2]	10		10
Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member]
Principal balance	[2]	150		174
Total recorded investment	[1],[2]	150		174
Recorded investment for which there is no related allowance	[1],[2]	0		0
Recorded investment for which there is a related allowance	[1],[2]	150		174
Related allowance	[2]	4		6
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member]
Principal balance	[2]	678		347
Total recorded investment	[1],[2]	656		325
Recorded investment for which there is no related allowance	[1],[2]	656		325
Recorded investment for which there is a related allowance	[1],[2]	0
Related allowance	[2]	0
Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Principal balance	[2]	294		303
Total recorded investment	[1],[2]	294		303
Recorded investment for which there is no related allowance	[2]	294		303	[1]
Recorded investment for which there is a related allowance	[1],[2]	0		0
Related allowance	[2]	0		0
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member]
Principal balance	[2]	3,529		3,619
Total recorded investment	[1],[2]	3,520		3,611
Recorded investment for which there is no related allowance	[1],[2]	3,520		3,611
Recorded investment for which there is a related allowance	[1],[2]	0
Related allowance	[2]	0
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Principal balance	[2]	3,152		2,921
Total recorded investment	[1],[2]	2,796		2,602
Recorded investment for which there is no related allowance	[1],[2]	2,796		2,602
Recorded investment for which there is a related allowance	[1],[2]	0		0
Related allowance	[2]	0		0
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member]
Principal balance	[2]	1,158		1,236
Total recorded investment	[1],[2]	1,149		1,229
Recorded investment for which there is no related allowance	[1],[2]	70		126
Recorded investment for which there is a related allowance	[1],[2]	1,079		1,103
Related allowance	[2]	142		160
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member]
Principal balance	[2]	17		30
Total recorded investment	[1],[2]	17		30
Recorded investment for which there is no related allowance	[1],[2]	17		5
Recorded investment for which there is a related allowance	[1],[2]			25
Related allowance	[2]			$ 1

[1] Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.

[2] Only classes with impaired loans are shown.