Note 9 - Commitments and Contingencies - Financial Instruments With Credit Risk (Details) - USD ($) |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Financial instruments whose contract amounts represent credit risk: | ||
| Standby and performance letters of credit | $ 142,500,000 | |
| Standby Letters of Credit [Member] | ||
| Financial instruments whose contract amounts represent credit risk: | ||
| Standby and performance letters of credit | 11,766,000 | $ 10,206,000 |
| Commitments to Extend Credit [Member] | ||
| Financial instruments whose contract amounts represent credit risk: | ||
| Commitments to extend credit | $ 337,415,000 | $ 311,424,000 |