Note 7 - Commitments and Contingencies - Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Commitments	$ 235,470	$ 227,744
Standby Letters of Credit [Member]
Commitments	7,113	6,692
Federal Home Loan Bank of San Francisco Affordable Housing Grant Sponsorships [Member]
Commitments	3,338	3,338
Commitments to Extend Credit [Member]
Commitments	$ 225,019	$ 217,714