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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Average recorded investment	$ 10,829	$ 15,015	$ 11,261	$ 16,385
Interest income recognized	78	66	236	200
Commercial Portfolio Segment [Member]
Average recorded investment	2,254	3,140	2,508	3,249
Interest income recognized	19	9	60	29
Commercial Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Interest income recognized
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	798	1,381	799	1,796
Interest income recognized	11	12	35	35
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Average recorded investment		624		692
Interest income recognized				2
Residential Portfolio Segment [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	7,154	7,907	7,272	8,080
Interest income recognized	43	40	126	120
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	181	634	231	1,155
Interest income recognized
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	412	1,291	418	1,330
Interest income recognized	5	5	15	14
Consumer Portfolio Segment [Member]
Average recorded investment	30	38	33	83
Interest income recognized