Note 4 - Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Average recorded investment	$ 15,015	$ 18,315	$ 16,385	$ 18,401
Interest income recognized	66	77	200	212
Commercial Portfolio Segment [Member]
Average recorded investment	3,140	2,601	3,249	2,551
Interest income recognized	9	10	29	14
Commercial Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Interest income recognized			2
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	1,381	2,010	1,796	2,015
Interest income recognized	12	12	35	35
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Average recorded investment	624	1,147	692	1,333
Interest income recognized		6		19
Residential Portfolio Segment [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	7,907	8,831	8,080	9,037
Interest income recognized	40	42	120	124
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	634	1,808	1,155	1,774
Interest income recognized
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	1,291	1,661	1,330	1,558
Interest income recognized	5	7	14	20
Consumer Portfolio Segment [Member]
Average recorded investment	38	257	83	133
Interest income recognized