Note 11 - Retirement Plans - Net Periodic Benefit Cost (Details) - Supplemental Employee Retirement Plan [Member] - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Service cost | $ 19 | $ 15 |
| Interest cost | 24 | 19 |
| Recognized net actuarial loss | 5 | |
| Net periodic benefit cost | $ 48 | $ 34 |
| Discount rate used to determine net period benefit cost | 3.39% | 3.22% |
| Discount rate used to determine benefit obligation at year end | 3.31% | 3.39% |
| Rate of compensation increase | 4.00% | 4.00% |