Note 4 - Loans and Allowance for Loan Losses - Loans Individually Evaluated for Impairment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Allowance for Loan Losses Allocated	$ 92		$ 94
Unpaid principal balance	18,050		19,917
Recorded investment	16,227		18,108
Average impaired loans	16,606	$ 18,091
Interest income recognized	204	180
Cash basis interest recognized	204	180
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Unpaid principal balance - with allowance recorded	371		372
Recorded investment - with allowance recorded	371		372
Allowance for Loan Losses Allocated	92		94
Unpaid principal balance - with no allowance recorded	4,966		4,989
Recorded investment - with no allowance recorded	3,507		3,534
Average impaired loans - with allowance recorded	371	382
Interest income recognized - with allowance recorded	1	5
Cash basis interest recognized - with allowance recorded	1	5
Average impaired loans - with no allowance recorded	3,521	3,822
Interest income recognized - with no allowance recorded	20	21
Cash basis interest recognized - with no allowance recorded	20	21
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Unpaid principal balance - with no allowance recorded	348		352
Recorded investment - with no allowance recorded
Average impaired loans - with allowance recorded		345
Interest income recognized - with allowance recorded
Cash basis interest recognized - with allowance recorded
Average impaired loans - with no allowance recorded		182
Interest income recognized - with no allowance recorded	5	4
Cash basis interest recognized - with no allowance recorded	5	4
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Unpaid principal balance - with no allowance recorded	2,478		3,427
Recorded investment - with no allowance recorded	2,478		3,427
Average impaired loans - with no allowance recorded	2,491	3,547
Interest income recognized - with no allowance recorded	34	36
Cash basis interest recognized - with no allowance recorded	34	36
Residential Portfolio Segment [Member]
Unpaid principal balance - with no allowance recorded	1,695		1,420
Recorded investment - with no allowance recorded	1,679		1,420
Average impaired loans - with no allowance recorded	1,550	918
Interest income recognized - with no allowance recorded	20	12
Cash basis interest recognized - with no allowance recorded	20	12
Commercial and Industrial Portfolio Segment [Member]
Unpaid principal balance - with no allowance recorded	8,192		9,154
Recorded investment - with no allowance recorded	8,192		9,154
Average impaired loans - with allowance recorded		392
Interest income recognized - with allowance recorded
Cash basis interest recognized - with allowance recorded
Average impaired loans - with no allowance recorded	8,673	8,292
Interest income recognized - with no allowance recorded	124	100
Cash basis interest recognized - with no allowance recorded	$ 124	100
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Unpaid principal balance - with allowance recorded			203
Recorded investment - with allowance recorded			$ 201
Average impaired loans - with allowance recorded		211
Interest income recognized - with allowance recorded		2
Cash basis interest recognized - with allowance recorded		$ 2