Note 8 - Commitments and Contingent Liabilities - Unused and Available Credit Balances of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial instruments	$ 178,139	$ 138,523
Financial Standby Letter of Credit [Member]
Financial instruments	49,889	36,657
Performance Guarantee [Member]
Financial instruments	4,396	2,471
Construction Mortgages [Member]
Financial instruments	23,825	21,363
Personal Line Of Credit [Member]
Financial instruments	6,271	5,905
Overdraft Protection Lines [Member]
Financial instruments	6,183	5,680
Home Equity Lines of Credit [Member]
Financial instruments	15,799	14,722
Commercial Lines Of Credit [Member]
Financial instruments	$ 71,776	$ 51,725