Note 9 - Commitments and Contingent Liabilities - Unused and Available Credit Balances of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial instruments	$ 232,209	$ 240,104
Financial Standby Letter of Credit [Member]
Financial instruments	40,906	42,041
Performance Guarantee [Member]
Financial instruments	2,667	2,521
Construction Mortgages [Member]
Financial instruments	77,672	59,689
Personal Line Of Credit [Member]
Financial instruments	6,561	6,456
Overdraft Protection Lines [Member]
Financial instruments	6,474	6,415
Home Equity Lines of Credit [Member]
Financial instruments	20,459	20,560
Commercial Lines Of Credit [Member]
Financial instruments	$ 77,470	$ 102,422